WHMCS Glossary
WHMCS is full of exciting features and useful tools. For the best experience, we recommend becoming familiar with our term glossary.
A
Access Hashes
Authentication tokens that some control panels use to authorize API access without a password. In WHMCS, some server and provisioning module configurations require an access hash for authentication.
Account Owners
Users who hold primary ownership of a client account. They can manage account-level data, billing, and permissions for associated users and contacts.
Activity Logs
The log of system and user actions in WHMCS. You can use it to audit activity, troubleshoot issues, and review security events.
You can view activity logs at Configuration () > System Logs.
Addon Modules
Modules that add features to WHMCS and do not depend on provisioning a specific product or service. Addon modules typically provide integrations, workflow tools, and custom admin functionality.
You can view and manage addon modules at Configuration () > System Settings > Addon Modules.
Addons
Optional features or services that customers can purchase with a product. In WHMCS, addons can use their own pricing, billing cycles, and automation settings.
You can configure product addons at Configuration () > System Settings > Product Addons.
Admin Area
The WHMCS interface where staff (admins) manage clients, services, orders, billing, and system settings.
Admin Logs
The log of admin login activity and session information.
You can view admin logs at Configuration () > System Logs.
Administrator Roles
Permission sets that define what admins can view and do in WHMCS. WHMCS includes three default roles: Full, Sales, and Support Only.
You can create and manage administrator roles at Configuration () > System Settings > Administrator Roles.
Admins
Staff accounts that access the WHMCS Admin Area to manage your business’s operations. Assigned administrator roles and optional restrictions define their capabilities.
Affiliates
Partners who refer customers to your business through links that track referrals. WHMCS can calculate commissions and manage affiliate payouts.
You can add and manage affiliates at Clients > Manage Affiliates.
Apache®
The supported web server software for self-hosted WHMCS installations.
Application Programming Interface (API)
A set of rules and endpoints that allows software systems to communicate and exchange data. WHMCS provides API methods so that third-party systems can securely create clients, manage invoices, and perform service actions.
API Credentials
Authentication credentials that allow for better management and security when provisioning access to API-connected devices and systems. You can create as many API credential pairs for an admin as you require.
You can create and manage API credentials at Configuration () > System Settings > Manage API Credentials.
API Roles
Permission profiles that provide an authorized subset of actions for API authentication credentials. API roles let you restrict integrations to the API actions that they need.
You can create and manage API roles at Configuration () > System Settings > Manage API Credentials.
Application Links
Client Area links that allow customers to move from supported third-party platforms like cPanel to the WHMCS Client Area using Single Sign-On.
You can configure application links at Configuration () > System Settings > Application Links.
Authorized Redirect URIs
Callback URLs that you must provide for authentication through services like OAuth2 or OpenID Connect™. WHMCS and integrated providers use them to prevent redirects to untrusted destinations.
Automatic Updater
A feature that allows you to update WHMCS quickly and easily from directly within the Admin Area. The system automatically checks for updates periodically, or you can check for updates manually.
You can update WHMCS at Utilities > Update WHMCS.
Automation
Scheduled or rule-based processes that perform tasks with minimal manual intervention. In WHMCS, automation runs invoicing, reminders, suspensions, renewals, and other time-based actions.
You can configure automation settings at Configuration () > System Settings > Automation Settings.
B
Base Conversion Rates
The currency ratios that WHMCS uses to calculate prices between the default currency and additional currencies. WHMCS applies these rates when presenting and converting multi-currency amounts.
You can configure base conversion rates at Configuration () > System Settings > Currencies.
Base URL
A required template variable that specifies the path to the WHMCS directory. WHMCS uses this variable when generating links in the Client Area or Admin Area.
Beta
An initial release of WHMCS that is still undergoing refinement and that may not yet include key features.
Billable Items
Invoiceable items that represent custom products or services that you plan to sell to a single client.
Billing Cycles
The intervals at which WHMCS invoices a service. Common billing cycles include monthly, quarterly, and annually.
Bugs
See Features.
Bulk Pricing Updater
An addon module that can apply system-wide price changes to existing clients’ products, domains, and addons.
C
Calling Codes
International telephone dialing prefixes that countries or regions use. WHMCS accepts them in contact and client phone numbers.
CAPTCHA
Completely Automated Public Turing test to tell Computers and Humans Apart, an anti-abuse challenge that reduces spam and automated submissions. WHMCS can apply it to forms like login, registration, and ticket creation.
You can configure CAPTCHA settings at Configuration () > System Settings > General Settings.
Cart
See Shopping Cart.
Certificate Authorities (CAs)
Trusted organizations that issue and validate SSL/TLS certificates.
Client Accounts
See Clients.
Client Area
The customer-facing area of WHMCS. Clients use the Client Area to manage services, invoices, support tickets, domains, and account details.
Client Groups
Categories that group client accounts and that you can use to assign discounts, termination and suspension exemption, and domain pricing slabs.
You can create and manage client groups at Configuration () > System Settings > Client Groups.
Clients
The entities that own products and services in WHMCS. A client account stores billing, service, domain, and contact data. Multiple users can access client accounts, each with different permissions.
Commission Reversals
Adjustments that remove or reduce previously awarded affiliate commissions. WHMCS usually applies these adjustments when a related order receives a refund, a cancellation, or a fraud status.
Configurable Options
Product options that let clients change attributes like storage limits or software tiers. Configurable options can change pricing based on the customer selection.
You can configure configurable options at Configuration () > System Settings > Configurable Options.
Configurable Package Addons
An addon module allows cPanel, WP Squared, and DirectAdmin hosts to offer customizable packages to your clients.
configuration.php Files
The core configuration file that stores environment-specific WHMCS settings like database connection values and system paths.
Contacts
Additional people that a client account links for notifications and specific communication purposes.
You can manage contacts in the Contacts tab in the client profile.
Continuous Invoice Generation
A feature that causes WHMCS to create invoices regardless of whether unpaid invoices exist for the service.
You can enable Continuous Invoice Generation in the Invoices tab at Configuration () > System Settings > General Settings.
Country Codes
Standardized short identifiers for countries. WHMCS uses the ISO-3166 standard for these codes.
cPanel Licensing
An addon module that uses cPanel’s Manage2 API to provide an automated solution for cPanel Partners to provision, manage, and bill for cPanel & WHM licenses.
Credit Balances
Client account credits in WHMCS. The system can automatically apply them toward unpaid invoices.
Credit Notes
An invoice item that reduces or eliminates the invoice balance. Businesses use credit notes to document refunds, price adjustments, returns, or corrections after they issue an invoice.
Cron Job
A system daemon that executes tasks at designated times. WHMCS’s automation relies on the system cron to perform many tasks.
Cron Tasks
Tasks that execute during a cron job run. The system cron run includes tasks for invoicing, reminders, renewals, and other periodic processing.
Cross-Selling
The practice of recommending related products to clients as they use the Client Area or Shopping Cart.
Custom Fields
Data fields that you can configure to capture additional information from or about your customers. WHMCS supports custom fields for clients, products, and support departments.
You can configure custom fields at Configuration () > System Settings > Custom Fields.
D
Daily Tasks
See Cron Tasks.
Data Feeds
A dynamic way to extract data from WHMCS for use on the pages of your website.
Data Retention Pruning
The automatic deletion of Inactive and Closed clients after a specified period of inactivity. Data retention pruning helps control database growth and supports data governance.
You can configure data retention pruning at Configuration () > System Settings > Automation Settings.
Database Backups
Copies of WHMCS database contents that teams use for disaster recovery, migration, and rollback scenarios. Regular backups reduce recovery risk.
You can configure database backups at Configuration () > System Settings > Database Backups.
Databases
Structured data that WHMCS uses to store clients, invoices, products, tickets, and other important information.
Debit Notes
An invoice item that increases the invoice balance. Businesses use debit notes to document additional charges like late fees or underbilling corrections.
Default Currency
The primary currency that WHMCS uses for pricing and conversion calculations. Additional currencies convert from this base.
You can manage currencies at Configuration () > System Settings > Currencies.
Development Licenses
Non-production WHMCS licenses that you can use for testing, development, and staging.
Disputes
Payment challenges that occur when a customer contests the charges that you collect. Disputes can include chargebacks, inquiries, or retrievals, as well as other items.
You can manage disputes at Billing > Disputes.
Distributions
Release packages of WHMCS files that you can use for installations and upgrades.
DKIM
An email authentication method that uses cryptographic signatures. DKIM helps receiving systems verify message legitimacy.
DNS Records
Zone entries that map domain names to resources. Common targets include IP addresses, mail servers, and verification tokens.
Domain Categories
Groups that organize domain TLDs on the Client Area Register Domain page.
Domain Control Validations (DCVs)
Checks that prove domain control before a certificate authority issues an SSL certificate. Common DCV methods include DNS, HTTP, and email validation.
Domain Extensions
Top-level domain (TLD) suffixes like .com or .net. Clients can register supported extensions through WHMCS.
You can configure domain extension pricing at Configuration () > System Settings > Domain Pricing.
Domain Grace Periods
Post-expiration windows during which you can usually renew a domain at standard or near-standard terms. This period follows the initial expiration date.
Domain Name Systems (DNS)
Distributed naming systems that translate human-readable domains into routable network information. DNS enables clients and services to locate internet resources.
Domain Pricing Slabs
Client-group pricing tiers that let you set different domain prices for selected clients or client groups. If a domain extension does not have a custom slab price, WHMCS charges the default base slab pricing.
Domain Redemption Periods
Post-grace windows after expiry where recovery is still possible. Recovery during redemption usually requires additional fees.
Domain Registrar Modules
WHMCS modules that connect to leading domain registrars, allowing you to easily sell domain registrations. Domain registrar modules handle registration, transfer, renewal, and domain management actions.
You can configure domain registrars at Configuration () > System Settings > Domain Registrars.
Domain Registrars
Accredited companies that sell and manage domain registrations with domain registries. WHMCS can integrate with registrars through domain registrar modules.
Domain Registrations
Successful domain purchases that create active domain records for a registrant through a registrar. Registration terms and pricing depend on the chosen extension and registrar.
Domain Renewals
The process of extending a domain’s registration term before or after its expiry date, based on registrar rules and available renewal windows. In WHMCS, domain renewals use configured pricing, invoice generation, and registrar module actions.
Domain Resolvers
DNS resolver services that answer DNS queries by retrieving or caching domain record responses. They return the records that clients and services use to reach domain resources.
In WHMCS, you can check the IP address that each domain in your WHMCS system is pointing to using the feature at Utilities > Domain Resolver.
Domain Sync
A system cron task that ensures that the next due date, expiry date, and status are up-to-date on all Pending Transfer, Pending Registration, and Active status domains.
Domain Transfers
Processes that move domain management from one registrar to another. They often require authorization and confirmation steps.
Dynamic Field Translations
A feature that allows you to translate supported database values, like the names and descriptions for products, into multiple languages.
E
EHLO
The SMTP extended greeting command. Mail clients and servers use EHLO to announce capabilities before sending mail.
Email Campaigns
Targeted outbound email that you send to selected groups of contacts or clients. You can use email campaigns to easily send announcements, updates, or marketing communications.
You can create and manage email campaigns at Utilities > Email Campaigns.
Email Importing
A method for converting incoming email messages into support tickets or ticket replies. We recommend using email importing if you use other control panels than cPanel & WHM or if you want to import email from multiple domains.
Email Marketer
A WHMCS feature for scheduling and sending emails using client and service criteria.
You can configure email marketing rules at Utilities > Email Marketer.
Email Message Logs
A log that records outbound email activity. Log messages include the recipients, templates, timestamps, and delivery context.
You can view email message logs at Configuration () > System Logs.
Email Piping
A method for converting email messages into support tickets or ticket replies directly from the mail server. We recommend using email piping if you use cPanel & WHM and only receive email replies from one domain.
Email Templates
Templated messages that WHMCS uses when it sends email to your clients. For example, when a client purchases a product, WHMCS sends a welcome email using the welcome email template for that product.
You can create and edit email templates at Configuration () > System Settings > Email Templates.
End of Life
A date after which a software version no longer receives regular maintenance updates or security fixes.
EPP Code
A domain transfer authorization code that a gaining registrar uses to verify a transfer request. Registries and registrars may also call this an auth code or transfer code.
Error Pages
User-facing pages that appear when requests fail. Common examples include 404 not found and 500 server error errors.
Escalation Rules
Automation rules that allow you to specify actions to take automatically if a support ticket is in a specified state for a set period of time.
You can configure escalation rules at Configuration () > System Settings > Escalation Rules.
Exchange Rates
Currency conversion values that WHMCS uses to translate prices and amounts between configured currencies. These values allow you to bill customers in multiple currencies.
You can configure exchange rates at Configuration () > System Settings > Currencies.
F
Features
See Bugs.
Fileinfo
A PHP extension that identifies file MIME types and related metadata. WHMCS uses it for upload validation and file-processing tasks.
Fraud Checks
Automated screening actions that evaluate orders for suspicious patterns before activation. They help reduce risk from fraudulent signups and payments.
You can configure fraud protection at Configuration () > System Settings > Fraud Protection.
Friendly URLs
Human-readable URL paths that improve usability and search indexing for some sections of the WHMCS Client Area.
G
Gateway Logs
The log of payment gateway requests and responses. Gateway logs help you audit and troubleshoot payment events.
You can view gateway logs at Billing > Gateway Log.
Gateways
See Payment Gateways.
General Availability
Feature-complete, well-tested versions of WHMCS that are ready to use on production servers.
Getting Started Wizard
A feature that helps you set up WHMCS quickly and easily. It allows you to configure many of WHMCS’s most important features and integrations in a few simple steps.
GMP
A PHP extension that supports large integer arithmetic and related mathematical operations. WHMCS may rely on it for calculations that exceed standard integer range.
Google Analytics™
A web analytics platform for tracking visitor behavior and conversion activity, or the WHMCS addon module that integrates Google Analytics into your online store.
Gravatar
An avatar service that displays profile images that email addresses map to. WHMCS displays Gravatar images in places that support profile avatars.
Greylisting
An anti-spam technique that temporarily rejects unknown senders. Legitimate mail servers usually try to send the message again, and the receiving server then accepts the message.
Goods and Services Tax (GST)
A tax model that businesses use in applicable jurisdictions, like India. WHMCS can apply GST through configured tax rules.
Guest Users
Visitors who can browse and begin ordering or reply to support tickets without authenticating as a client.
Globally Unique Identifiers (GUIDs)
Unique identification numbers for records, objects, or other entities.
H
HELOs
SMTP greeting commands that identify the sending host in mail server communication. HELO commands are part of the SMTP handshake.
Homepage Panels
Configurable content sections that display in the WHMCS Client Area.
HipChat™
A team communication platform that WHMCS can integrate with for notifications. WHMCS can send supported admin notifications to connected HipChat channels.
You can configure HipChat notifications at Configuration () > System Settings > Notifications.
I
ICANN
The organization that is responsible for coordinating global domain name and IP address policy frameworks.
iconv
A character encoding conversion library and PHP extension. WHMCS can use it for text encoding transformations and compatibility.
Import Files
CSV files that the ImportAssist addon module uses to import records from other systems.
ImportAssist
An addon module for importing data from external billing platforms into WHMCS.
Integration
A connection between WHMCS and an external or third-party system. WHMCS includes a large number of integrations that we ship with WHMCS by default, and you can find more integrations for self-hosted WHMCS installations in the WHMCS Marketplace.
You can find and activate integrations at Configuration () > Apps & Integrations.
International Domain Names
Domain names that include language-specific scripts like Hebrew, Arabic, Chinese, or some types of Latin characters. They allow domain registrations in many local scripts and languages.
Intl
A PHP internationalization extension for locale-aware formatting and language-sensitive operations. WHMCS uses it for regional display behavior.
Immutable Invoices
Invoices that have transitioned out of the draft status. To maintain consistent and accurate financial records and for easier auditing and tax compliance, you cannot edit these invoices.
Invoices
Billing documents that list charges, credits, taxes, and totals that a client owes for products and services. In WHMCS, invoices track due dates, payment status, and related transactions.
You can manage invoices at Billing > Invoices.
ionCube Loader®
A PHP extension that WHMCS requires to execute encoded core files. WHMCS installations must load a compatible ionCube Loader version.
IP Addresses
Numeric network identifiers that systems use for server communication, access controls, and service configuration. WHMCS uses IP addresses in automation, integrations, and security settings.
IRTP Transfer Locks
Policy-based restrictions that can temporarily block domain transfers after registrant or ownership changes. They are part of transfer security and ownership change compliance rules.
J
JSON
A lightweight data-interchange format based on key-value structures and arrays. WHMCS and third-party integrations commonly use it for API payloads.
K
Knowledgebase
A searchable collection of self-service help content. Clients can use these articles to find answers to common questions without opening support tickets.
You can manage your knowledgebase articles at Support > Knowledgebase.
L
LAMP
A web hosting environment that uses Linux, Apache, MySQL® or MariaDB®, and PHP. WHMCS runs in LAMP-compatible environments.
Ledgers
A list of all financial activity for an invoice, including original charges, received payments, credit and debit notes, and the invoice’s current balance.
You can view invoice ledgers at Billing > Invoices.
Link Tracking
A feature that lets you track advertising and promotion performance using WHMCS-generated tracking links. WHMCS records clicks and conversions with a cookie so that you can evaluate link effectiveness.
You can access link tracking at Utilities > Link Tracking.
Linux®
A Unix-like operating system platform that you can use to host WHMCS.
Locales
Regional language and formatting settings. They affect dates, numbers, currencies, and translations.
Login Sessions
Authenticated user or admin sessions that remain active for a configured duration.
Long-Term Support (LTS)
WHMCS versions that receive targeted Critical and Security releases from our development and security teams until the EOL date. These releases do not include product enhancements or maintenance fixes unless they are critical for the viability of a targeted release.
Lookup Providers
External services that WHMCS searches to determine whether a domain is available for purchase in the Client Area’s domain checker or shopping cart.
M
Mail Providers
Services that WHMCS uses to send outbound email. You can choose from several supported mail provider configuration options in WHMCS.
Mail Transfer Agents (MTAs)
Mail server components that route and deliver email messages. WHMCS outbound email passes through an MTA or API-based provider.
Maintenance Releases
WHMCS updates that are focused on fixes, security improvements, and minor stability enhancements. They do not usually introduce major feature changes.
Manual Gateways
Payment gateways where WHMCS records payment methods without fully automated real-time capture. They rely on off-platform payment confirmation or manual posting.
MariaDB
A relational database server that is compatible with MySQL protocols and tooling. WHMCS supports MariaDB in supported version ranges.
MarketConnect
A platform that lets you resell high-quality products like website builders and email security services to your customers through WHMCS.
You can configure MarketConnect at Configuration () > System Settings > MarketConnect.
Marketplace
See WHMCS Marketplace.
mbstring
A PHP extension for multibyte string handling. WHMCS uses it to process Unicode-safe text operations.
Merchant Gateways
Payment gateways that store credit card information securely in the WHMCS database.
Merge Fields
Template placeholders that insert dynamic values into emails, invoices, support tickets, and other generated content. WHMCS replaces them with context-specific data.
Metric Pricing
Usage-based pricing that WHMCS calculates from measured consumption units. WHMCS can bill these metrics through configured usage and pricing rules.
You can configure metric pricing in the Module Settings tab at Configuration () > System Settings > Products/Services.
mod_rewrite
An Apache module that rewrites URLs using rule sets. WHMCS uses rewrite rules for friendly URLs and routing behavior.
Models
Structured application objects that represent and manage data entities. In WHMCS development contexts, models typically map to persisted records and relationships.
Module Commands
Commands that WHMCS sends to modules for service or domain lifecycle events. Common commands include create, suspend, unsuspend, terminate, and renew.
Module Log
A log of module operations and outcomes. WHMCS uses these logs for recordkeeping and troubleshooting.
You can view the module log at Configuration () > System Logs.
Module Templates
Reusable file structures and patterns for creating WHMCS modules. They provide baseline scaffolding for supported module types.
Modules
Integrations that connect WHMCS to provider APIs and external services. Common module categories include server provisioning, domain registrar, and payment gateway modules.
MX Records
DNS records that define which mail servers receive email for a domain. They route inbound mail traffic to configured destinations.
MySQL
A relational database management system commonly used with WHMCS. It stores core operational, billing, and configuration data.
mysqlnd
The MySQL Native Driver extension for PHP. WHMCS depends on compatible PHP database drivers to connect and query its database.
N
Nameservers
DNS servers that host and serve domain zone data. Domain delegation points resolvers to these authoritative servers.
Namespinning
A tool that provides intelligent automated suggestions based on the domain, keywords, or description that a user enters. It generates, ranks, and returns relevant domain name suggestions across a wide range of TLDs.
Next Due Date
The date when the client’s next renewal payment is due. WHMCS usually generates invoices in advance based on your installation’s automation settings and then moves this date forward by one billing cycle after payment.
Next Invoice Date
The scheduled date when WHMCS will generate the next invoice. These dates can differ from next due dates depending on lead time settings.
NGINX®
A web server and reverse proxy platform that some WHMCS installations use instead of Apache.
Notifications
System-generated messages that inform admins, users, or clients about events and required actions. In addition to email notifications, WHMCS integrates with popular team communication apps, including Slack and HipChat.
You can configure notifications at Configuration () > System Settings > Notifications.
O
OAuth
A protocol that allows third-party applications to obtain limited access to WHMCS on behalf of users. WHMCS uses OAuth 2, an open specification that allows users to authenticate with WHMCS, verify their identity, and grant apps permission to access their data.
On-Demand Renewals
A feature that lets your clients renew services early, before the system generates their next invoice, with no manual staff intervention.
OpenID Connect
The standard for single sign-on and identity provisioning on the internet. It uses JSON-based identity tokens (JWT) via the OAuth 2.0 protocol.
OpenSSL
A cryptographic library that systems use for SSL/TLS operations and certificate handling. WHMCS relies on OpenSSL through PHP and system components.
Order Form Templates
Predefined layouts for the WHMCS checkout experience. They control how products, domains, and cart steps appear to customers.
Orders
Customer purchase records that include selected products, domains, and billing context. WHMCS processes orders through review, fraud checks, payment, and acceptance workflows.
Overage Billing
Billing based on the amount of disk or bandwidth that a customer used over the base amount for the package. WHMCS calculates overage charges from configured usage and pricing rules.
Overpayments
Payments that exceed the balance due on an invoice. The system automatically credits overages to a customer’s account balance if invoice overpayment occurs.
Override Templates
Custom module template files that you can use to override default module template output on self-hosted WHMCS installations. This override system lets you customize module display without losing your changes during WHMCS updates.
P
Pay Methods
Saved payment instruments and payment preferences that a client account stores. WHMCS uses pay methods for invoice checkout and automatic payment attempts.
Payment Capture
The process of finalizing and collecting authorized payment funds. WHMCS performs capture actions through supported gateway integrations.
Payment Gateway Modules
WHMCS module integrations that connect to payment providers. They implement gateway-specific payment, tokenization, and callback behavior.
You can configure payment gateway modules at Configuration () > System Settings > Payment Gateways.
Payment Gateways
Services that securely process customer payments. WHMCS supports online and manual payments through integrated payment gateway modules.
Payment Reversals
Financial actions that reverse or negate prior payment activity. Examples include chargebacks, reversals, and refunded settlements.
PDO_MySQL
The PHP Data Objects driver for MySQL-compatible databases.
PHP
A server-side scripting language that WHMCS requires in order to run.
Premium Domains
Domain names that registries or resellers price above standard registration rates. WHMCS can display and bill premium pricing when registrars support that data.
Private Keys
Secret cryptographic keys that systems use for decryption, signing, or certificate operations. You must protect private keys and never disclose them publicly.
Product Addons
See Addons.
Product Bundles
Collections of products and related options sold together. Bundles simplify packaging and can apply shared pricing or promotional logic.
You can configure product bundles at Configuration () > System Settings > Product Bundles.
Product Groups
Catalog groupings that teams use to organize products in storefront and order forms. They control display structure and navigation.
You can configure product groups at Configuration () > System Settings > Products/Services.
Products
Items that clients can purchase through the order form. Products typically use fixed pricing, but you can customize them with configurable options and product addons.
You can configure products at Configuration () > System Settings > Products/Services.
Proforma Invoicing
A billing approach where WHMCS issues an initial invoice document before final tax or accounting treatment. It supports prepayment workflows in applicable jurisdictions.
You can configure proforma invoicing in the Invoices tab at Configuration () > System Settings > General Settings.
Project Management Addon
An addon module that helps you organize tasks by linking support tickets, invoices, and to-do items into projects. You can manage them in a single interface, track internal discussions, share files, and track or bill time on individual tasks.
Promotions
WHMCS applies discount rules and special offers to eligible orders. Promotions can target products, billing cycles, domains, and date ranges.
You can configure promotions at Configuration () > System Settings > Promotions and Coupons.
Prorata Billing
Partial-period billing that businesses use to align service renewals to a fixed billing day. WHMCS calculates prorated first charges based on the remaining period.
Provisioning Modules
WHMCS modules that automate tasks on external platforms. They connect WHMCS product events to provider APIs.
Public Keys
Cryptographic keys intended for public distribution. Systems use public keys to verify signatures or encrypt data for the matching private key holder.
Q
Quotes
Pre-invoice pricing documents that teams issue for approval before billing. Accepted quotes can convert into invoices or orders.
You can manage quotes at Billing > Quotes.
R
Rate Limits
Limits on requests or actions over a set time period. Rate limits protect system resources and integrations from excessive activity.
Recurring Amount
The renewal invoice amount for a service when the Next Due Date differs from the Registration Date. It usually equals the product price plus selected configurable options.
Refunds
Returned funds that teams issue to reverse or reduce prior payments. WHMCS records refunds against invoices and related transactions.
Registrar
See Domain Registrars.
Registrar Locks
Domain-level transfer protection flags that prevent unauthorized registrar transfers. You usually remove locks before you submit a valid transfer request.
Registrar TLD Sync
A synchronization process that updates local domain pricing from registrar or configured source data. It helps keep registrar-based prices current.
You can access Registrar TLD Sync at Utilities > Registrar TLD Sync.
Release Tiers
The stages of WHMCS’s development cycle, from an initial release as a Beta, through multiple development and maintenance tiers, and finally to End of Life (EOL).
Renewals
Billing and service continuation events that extend active terms. Renewals apply to products, services, and domains based on due schedules.
Reseller License Manager
An addon module for members of the WHMCS Reseller Program. It allows you to view and manage the licenses in your WHMCS account, provision new licenses, and provision and reissue license keys.
Risk Score
The numerical value that MaxMind assigns to estimate an order’s risk level.
S
Sandboxes
Testing environments or accounts that simulate live system behavior. Sandbox transactions do not create real charges, and you should disable sandbox mode when you move to production.
Scheduled Actions
Automated actions that you can add for an individual support ticket. You can schedule updates to the ticket status or department, add notes or replies, and perform other actions on a scheduled date or after a set amount of time.
Security Questions
Identity verification prompts that add an additional account security factor. WHMCS can require security questions during login or password resets.
You can configure security questions at Configuration () > System Settings > Security Questions.
Security Releases
Software updates that address important issues and vulnerabilities that could affect your WHMCS installation. If you use a self-hosted WHMCS installation, we recommend applying security updates as soon as possible to keep your WHMCS installation safe.
Self-Hosted Installation
A WHMCS instance where you install and operate WHMCS on your own hosting infrastructure. You manage all system requirements, updates, and environment security, and can also install and use third-party customizations and modules.
Server Groups
Collections of servers for product assignment and load distribution. WHMCS can provision new services to servers in a group using configured rules.
Server Provisioning Modules
Provisioning modules specifically for server and hosting account lifecycle automation. They create and manage accounts on supported control panels or platforms.
You can configure server provisioning modules at Configuration () > System Settings > Servers.
Services
The individual instances of products after a client purchases them.
Setup Tasks
Initial configuration and feature activation tasks that we recommend for new WHMCS instances. They prepare WHMCS for production use.
Shopping Cart
The checkout workflow where customers review selected products, domains, and addons before placing an order. In WHMCS, the shopping cart applies pricing rules, promotions, and configurable options during order submission.
Slack®
A team communication platform that WHMCS can integrate with for notifications. WHMCS can send supported admin notifications to connected Slack workspaces or channels.
You can configure Slack notifications at Configuration () > System Settings > Notifications.
Sign-In Integrations
Authentication integrations that allow customers to connect with Facebook®, Google®, or X™ (formerly Twitter) in order to quickly sign up for an account or log in to the Client Area.
You can configure sign-in integrations at Configuration () > System Settings > Sign-In Integrations.
Simple Mail Transfer Protocol (SMTP)
The standard protocol for sending email between clients and mail servers. WHMCS can deliver outbound mail through SMTP-configured providers.
Single Sign-On
Authentication flows that allow users to move from WHMCS to interfaces in cPanel & WHM or Plesk without logging in again.
Smarty Security Policies
Security hardening measures that protect a system. WHMCS applies a Smarty Security Policy for system-wide use and a mail policy for stored and dynamic email-based templates.
SOAP
A protocol for exchanging structured XML messages between systems. Some legacy integrations and APIs rely on SOAP operations.
Software Licensing Addon
An addon module that allows you to license your own web applications for selling to end users. You can generate local license keys and configure periodic remote checking to ensure secure licensing for your products.
SPF
A DNS-based email authentication mechanism that defines which mail servers may send for a domain. SPF helps reduce sender spoofing.
Spotlight TLDs
Highlighted top-level domain offers that display prominently in your online store.
SSL Certificates
Digital certificates that bind domain identities to cryptographic keys for encrypted HTTPS communication. You can easily sell SSL certificates to your customers using WHMCS MarketConnect.
SSL Monitoring
A feature that allows you to easily see which domains have valid SSL certificates. SSL status displays in real time for services in both the Client Area and Admin Area.
SSO
See Single Sign-On.
Stable Releases
See General Availability.
Standard Hooks
Hooks that run when specific WHMCS actions occur. The system can accept returned values, but standard hooks do not perform return-value validation.
Status Monitoring
A feature that allows you to view the load and uptime for each of your Linux-based servers from within the WHMCS Client Area or Admin Area.
Storage Locations
Configured destinations for storing different types of files (for example, downloads, images, or email attachment files). Locations can be local paths or remote storage providers.
You can configure storage locations at Configuration () > System Settings > Storage Settings.
Support Departments
Support ticket routing groups that help you categorize tickets. You can assign staff to departments so that different people handle different areas. Sales, Support, and Billing are common departments.
You can manage support departments at Configuration () > System Settings > Support Departments.
Supported Versions
WHMCS release lines that receive active maintenance and updates. Support status determines update, fix, and security coverage.
Suspensions
Module actions that pause access to a service account on the connected platform. Suspensions retain account data while blocking active use, typically due to nonpayment.
System Cron
A system daemon that executes tasks at designated times. WHMCS relies on the system cron to automate many tasks, including billing, invoicing, payment capture, and more.
System Environment Log
A log view of environment and runtime diagnostics relevant to WHMCS operation. It helps identify configuration and compatibility issues.
You can view the System Environment Log at Configuration () > System Logs.
System Environment
The combined runtime context in which WHMCS operates, including OS, web server, PHP, database, and extensions. Environment compatibility affects stability and feature support.
System Health Checks
Operational status indicators and checks that highlight any potential configuration- or security-related issues that may need your attention.
You can review system health checks at Configuration () > System Health.
System Requirements
The minimum and recommended software prerequisites for running WHMCS. Requirements include supported PHP, database, extensions, and server components.
System Themes
Themes that allow you to provide a seamless experience for your website visitors by customizing the look of the Client Area to match the rest of your website.
System URL
The URL that you use to access your WHMCS installation.
You can configure the System URL at Configuration () > System Settings > General Settings.
T
Tax Rules
Configured logic that determines how tax rates apply to products, services, and jurisdictions. WHMCS evaluates these rules during invoice calculation.
You can configure tax rules at Configuration () > System Settings > Tax Configuration.
Temporary Update Path
A staging path that WHMCS uses during update preparation and extraction workflows. It provides temporary storage while WHMCS processes update files.
You can configure the temporary update path at Utilities > Update WHMCS.
Terminations
Module actions that delete service accounts on connected platforms. After termination, WHMCS retains the internal service record.
Test Environments
Non-production environments that you can use to validate configuration, integrations, and changes before live deployment. They reduce risk by isolating experimentation.
Ticket Collision Detection
A safeguard that prevents you from replying to a ticket or making changes when the status of a ticket has changed since you originally opened it in your browser. It helps prevent overlapping or conflicting responses.
Ticket Feedback Ratings
Clients submit satisfaction scores after ticket resolution. These ratings help measure support quality and trends.
Ticket Mail Import Log
A log of inbound email-to-ticket import processing events. It helps diagnose ticket creation and reply ingestion issues.
You can view the Ticket Mail Import Log at Configuration () > System Logs.
Time-Based Tokens
See TOTP Tokens.
Time Billing Entries
A type of billable item that allows you to bill for time that your staff spends working on a project.
TLDs
See Domain Extensions.
TLS
Transport Layer Security (TLS), the protocol that secures network communication channels. WHMCS relies on TLS for secure web and API traffic.
Tokenization
The process of replacing sensitive payment data with non-sensitive tokens. Tokenization reduces direct exposure of card data.
Tokenization Gateways
Payment gateways that store payment credentials and return reusable tokens. WHMCS uses these tokens for recurring and one-click payment flows.
TOTP Tokens
Time-based One-Time Password Tokens, a two-factor authentication method where users enter a six-digit code that regenerates every 30 seconds along with their username and password.
You can configure TOTP token services at Configuration () > System Settings > Two Factor Authentication.
Tracked URLs
See Link Tracking.
Transactions
Recorded payment events that WHMCS links to invoices, gateways, and clients. Transactions capture amounts, dates, statuses, and references.
You can view transactions at Billing > Transactions List.
Transliteration
Character conversion from one script or representation to another. WHMCS may use transliteration for compatibility in domain or string handling.
Trusted Proxies
Proxy servers that you explicitly allow to forward client request metadata. Trusted proxy settings ensure WHMCS interprets origin IP address and protocol correctly.
Two-Factor Authentication (2FA)
Authentication methods that enhance security by adding a second step to the login process. It combines something that you know (for example, your password) with a second factor, typically from something that you have (for example, your phone).
U
Unsuspensions
Module actions that reactivate previously suspended service accounts. WHMCS sends the unsuspend request to the connected server or service platform.
You can configure automatic unsuspensions at Configuration () > System Settings > Automation Settings.
Update Channel
A setting that determines which WHMCS releases the Automatic Updater feature will attempt to apply to your self-hosted WHMCS installation.
You can configure the update channel at Utilities > Update WHMCS.
Update Dry Run
A test that the Automatic Updater feature uses to check existing file permissions before beginning an update. If permissions are incorrect, the system logs an Apply update dry-run error, and the update process fails.
URIs
Uniform Resource Identifiers that systems use to identify resources and endpoints. WHMCS configuration and integrations frequently rely on correctly formed URIs.
Usage Billing
Billing based on measured consumption rather than fixed recurring amounts. WHMCS calculates charges from configured metrics and usage records.
User Activity Tracking
Logging of information about how admins navigate the WHMCS Admin Area and use its features. Admins must consent to user activity tracking before data collection begins.
Users
Account-level identities that can access one or more client accounts in WHMCS. User permissions determine which actions and data they can access.
UUIDs
Universally Unique Identifiers that systems use to reference objects without relying on sequential IDs. UUIDs reduce collision risk across distributed systems.
V
VAT
Value Added Tax (VAT), a consumption tax that applies in many jurisdictions. WHMCS can calculate and apply VAT using configured tax rules.
You can configure VAT settings at Configuration () > System Settings > Tax Configuration.
W
WHMCS Cloud
A hosted WHMCS deployment offering that WHMCS manages. It provides a cloud-hosted alternative to self-hosted installations.
WHMCS Connect
A feature that allows you to access servers that use supported control panels without reauthenticating.
You can access WHMCS Connect at Utilities > WHMCS Connect.
WHMCS Marketplace
A platform where you can find additional integrations and addons to add to your self-hosted WHMCS installation.
You can browse marketplace integrations and addons at Addons > Apps & Integrations.
WHOIS Lookup Logs
Records of WHOIS query activity and responses. They help audit domain lookup behavior and troubleshoot query issues.
You can view WHOIS lookup logs at Configuration () > System Logs.
WHOIS Lookups
A lookup provider that checks domain availability directly using WHOIS servers. In WHMCS, this is the default lookup provider.
Widgets
Configurable UI components that display focused data or shortcuts on dashboards. In WHMCS, widgets comprise most of the contents of the Admin Dashboard.
WP Toolkit
An all-in-one management solution for WordPress® installations. It simplifies WordPress management with AI-powered automated updates, site migrations, plugin management, theme management, and more.
For more information, see:
Last modified: 2026 March 17