Moodle — Codebase Overview

Repository

Field	Detail
GitHub	moodle/moodle (mirror of git.moodle.org)
Stars	6,910
Forks	7,356
License	GPL-3.0
Primary Language	PHP (~86% by code volume)
Total Commits	~121,000+
Contributors	216 on GitHub (broader community much larger)
Created	2001 (GitHub mirror established 2009)

Language Breakdown

Language	Approximate %
PHP	86.1%
JavaScript	9.1%
Gherkin (Behat tests)	2.3%
CSS	1.2%
Mustache (templates)	1.0%
SCSS	0.3%
TypeScript	<0.1% (emerging)

Tech Stack

• Backend: PHP (custom framework, not based on Symfony/Laravel)
• Database: MySQL/MariaDB (most common), PostgreSQL, Microsoft SQL Server (multi-database abstraction layer via DML/DDL)
• Frontend: JavaScript (vanilla + AMD modules), jQuery (being reduced), Bootstrap 5 (as of 5.0/5.1)
• Template Engine: Mustache templates (server-side rendered)
• Build Tools: Grunt for CSS/JS compilation
• APIs: REST, XML-RPC, and SOAP web services; Mobile app API; External Functions API
• Standards: LTI 1.1/1.3, SCORM 1.2/2004, xAPI, IMS Common Cartridge, QTI
• Caching: Multi-layer caching (APCu, Redis, Memcached)
• Search: Pluggable search engine support (Solr)
• Task Processing: Built-in scheduled task and ad-hoc task system (cron-based)
• Testing: Behat (acceptance testing, ~2.3% of codebase), PHPUnit (unit testing)
• Requirements: PHP 8.2+ (8.3, 8.4 supported), 64-bit only, sodium extension required

Architecture Highlights

• Plugin architecture is Moodle's defining characteristic — 1,900+ community plugins available, with 40+ plugin types (activities, blocks, themes, question types, authentication, enrollment, repositories, etc.)
• Moodle's core is a monolithic PHP application with a modular internal structure
• 250+ database tables (aggregate of core + plugin tables)
• Database abstraction layer (DML/DDL) supports multiple RDBMS engines
• Hooks API (introduced 4.4, matured 4.5+) — plugins register callbacks in db/hooks.php; supports pre/post/validation stages. Replacing legacy callback system.
• Events API — action-based event broadcasting to observers (one-way, one-to-many)
• External Functions API + Web Services — fully parameterized methods exposed via REST/SOAP/XML-RPC
• AI Subsystem (introduced 4.5) — pluggable provider architecture for AI models (OpenAI, Azure, Ollama)
• Renderer/output layer separates logic from presentation
• Role-based access control with fine-grained capabilities system
• Multi-tenant not built-in (each instance typically serves one organization), though Moodle Workplace adds multi-tenancy
• Plugins are folders of PHP, CSS, JS with defined entry points (typically lib.php)

Current Versions

Version	Type	Released
5.1.3	Current stable (latest patch)	2026
5.1.0	Major release	October 2025
5.0.6	Previous stable (latest patch)	2026
5.0.0	Major release	April 2025
4.5.x	LTS (long-term support)	October 2024
5.2dev	Development	Weekly builds on main

Release cadence: biannual major releases (April and October). Even-numbered minor releases (4.1, 4.3, 4.5) are LTS versions.

Recent Development Activity

Moodle is very actively developed, with ~4,500 commits since January 2025 (~10+ commits/day), regular weekly integration builds on the main branch. Recent sample commits (March 2026):

• weekly release 5.2dev
• NOBUG: Add upgrade notes
• MDL-87264 core_question: fix upgrade notes missing type declaration
• MDL-87922 — various community-contributed fixes

Development uses a Jira-based tracker (MDL-xxxxx issue keys) with a structured peer review and integration process. Key committers include Moodle HQ staff and community contributors via pull requests.

Moodle 4.5 LTS Key Features

• AI Subsystem introduced: Foundational AI placement and provider architecture
• Hooks API matured: Plugins can add/reorder secondary navigation menu items
• Bootstrap 5 refactoring began (Boost theme)
• Subsections feature: Nested course sections
• New progress bar API for adhoc tasks
• New web services for badges, private files, and submission removal

Moodle 5.0 Key Features (April 2025)

• Full Bootstrap 5 adoption: Cleaner code, faster load times, better mobile responsiveness
• AI "Your Way" philosophy: Support for multiple AI providers (OpenAI, Azure, Ollama for self-hosted)
• Granular AI access controls configurable at course and activity level
• AI policy acceptance report and AI usage monitoring report
• Activities Overview page: Consolidated view of activities, deadlines, submissions, grading
• Color-coded activity icons for improved navigation
• Relative date display ("Today", "Yesterday" instead of raw dates)
• Improved question bank filtering
• PHP 8.2+ required (8.3, 8.4 supported); 64-bit only; sodium extension required

Moodle 5.1 Key Features (October 2025)

• New /public directory: Web server document root must now point to /public — breaking infrastructure change improving security
• New Routing Engine: Cleaner URLs, improved request handling
• Redesigned Activity Selector: Activities grouped by purpose (assessment, collaboration, communication, resources, interactive content)
• SMS notification support for administrators
• Activities overview page expanded: Now covers forums, quizzes, H5P, wikis, lessons, glossaries, BigBlueButton sessions
• Rich text editor improvements: Drag-and-drop media, improved image captions for accessibility
• Large question bank performance: Better handling of very large question banks and shared questions
• Continued AI integration improvements
• More mature BigBlueButton integration

Upcoming: Moodle 5.2 / 5.3

• Chat and Survey modules leaving core (becoming external plugins)
• Legacy callback system being replaced by Hooks API
• Ongoing deprecation cleanup of functions from 4.0 and earlier
• TypeScript adoption beginning

Key Technical Characteristics

• PHP-only backend: No compiled languages or separate application servers required
• Extremely broad hosting compatibility: Runs on commodity shared hosting up to enterprise infrastructure
• Mature plugin API: Well-documented, stable plugin interfaces across 40+ extension points
• Upgrade path: Reliable version-to-version upgrade system with built-in database migration
• Localization: Translated into 100+ languages via community translation platform (AMOS)
• Mobile: Official Moodle Mobile app (Ionic/Angular) with offline support
• Largest single-instance deployment: Open University of Beijing with 3.5 million users

Development Governance

• Moodle HQ (Moodle Pty Ltd, based in Australia) leads core development
• Open contribution model with peer review process
• Community plugins hosted on moodle.org/plugins
• Biannual major release cycle (April and October)
• Long-term support (LTS) releases on even-numbered minors, maintained for extended periods
• Open Jira-based issue tracker (tracker.moodle.org)