LicenseForge - Free & Open-Source Software Licensing Add-on for WHMCS

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Hi everyone,

I wanted to share a project I've been working on that may be useful to other WHMCS developers who build and distribute commercial modules, addons, themes, or standalone software.

I've released LicenseForge, a free and open-source software licensing platform built specifically around WHMCS.

GitHub: https://github.com/zaltom/LicenseForge

The idea is fairly simple: use WHMCS as the commercial/billing authority while LicenseForge handles the actual software licensing, activation, validation, installation binding, entitlements, and related functionality.

What does it do?

LicenseForge provides:

• WHMCS-native license provisioning

• License activation and periodic validation

• Domain, IP, directory, and machine-ID binding

• Configurable activation limits

• License reissues and reissue limits

• Billing-cycle, lifetime, and fixed-term licenses

• Grace periods and renewal handling

• Feature entitlements

• Minimum/maximum/latest version restrictions

• Customer self-service license reissues

• Protected WHMCS product downloads

• License expiry and lifecycle notifications

• Abuse detection

• Detailed audit logging

• Signed offline license validation

• API credentials with scopes and rate limiting

• PHP, Python, and .NET client SDKs

It also integrates directly with the WHMCS product/service lifecycle.

How it works

The general flow is:

WHMCS Product → Customer Order → License Issued → Software Activation → Periodic Validation → Entitlements / Version Rules

A license is associated with the WHMCS service, so billing and licensing remain connected.

For example, you can configure a product to automatically issue a license when an order is paid, limit the number of installations, restrict the license to a domain or machine, and have the client periodically validate the license against your WHMCS installation.

Client SDKs

The repository currently includes clients for:

• PHP

• Python

• .NET

The licensing API is intentionally small, with activation and validation operations, and supports signed requests and offline validation.

Security

Security was an important part of the design rather than something added afterwards.

Some of the included protections are:

• CSRF protection

• API request signing

• Replay protection using nonce/timestamp validation

• Encrypted sensitive secrets

• Protected storage

• Audit logging

• Rate limiting

• Credential scopes

• Installation binding

• Abuse detection

• Ed25519 / RSA signature verification

• Signed offline validation payloads

The client SDKs also support fail-closed validation rather than silently treating an invalid license as valid.

Requirements

Currently LicenseForge targets:

• WHMCS 9.x

• PHP SODIUM

Both the addon and server provisioning modules are included in the repository.

Why open source?

There are already several commercial licensing solutions available, but I wanted to build something that developers could fully inspect, modify, and host themselves.

There is no external licensing service required. You run it alongside your own WHMCS installation and retain control over the licensing data and infrastructure.

The project is currently at v1.0.0, and I'm interested in getting it into the hands of other WHMCS developers and improving it based on real-world use.

If you develop WHMCS modules or other software that needs licensing, I'd love to hear your feedback.

GitHub: https://github.com/zaltom/LicenseForge

Issues, suggestions, testing, and pull requests are all welcome.

Thanks!