The Blender Developer Documentation can be found under developer.blender.org/docs.

Modules

Blender development is organized into modules and projects with different teams.

General

Module	Topics
Core	DNA & RNA, .blend file, undo, datablocks, linking, overrides, support libraries
Development Management	Communication, documentation, forum, onboarding, infrastructure
Platforms & Builds	Windows, macOS, Linux, build system, release builds, libraries
Triaging	Triaging bug reports and first round of pull request review
User Interface	Interface, window manager, internationalization, tools & operators, outliner

Features

Module	Topics
Animation & Rigging	Graph editor, dopespheet editor, NLA editor, keyframes, drivers, constraints, armatures
Asset System	Local and remote assets handling
Grease Pencil	Grease pencil drawing, editing, sculpting and all related to 2D animation module in Blender
Modeling	Meshes, modifiers, nurbs, curves, metaballs, transform, UV editor, subdivision surfaces
Nodes & Physics	Geometry nodes, function nodes, node editor, simulations, rigid body, cloth, softbody, fluids
Pipeline & I/O	Import/export and integration into production pipelines
Python API	Python API, text editor and console
EEVEE & Viewport	EEVEE, workbench, overlays, GPU, OpenGL, Vulkan, Metal, multi-view, virtual reality
Render & Cycles	Cycles, render pipeline, materials, textures, Freestyle, baking and color management
Sculpt, Paint & Texture	Sculpting, vertex and image painting
VFX & Video	Video sequencer, compositor, motion tracking, Libmv, audio