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Best Open-Source Game Engines for 2026 ​

Best open-source game engines for 2026

Open-source game engines give you something proprietary ones can't: a license that won't change after you've shipped. No per-seat fees, no revenue thresholds, no surprise pricing. You can read the source, fork it, and keep building even if the original team walks away. After the Unity Runtime Fee episode, that stability is exactly why a lot of teams moved to open source in the first place.

This is the complete list of open-source game engines worth using in 2026, grouped by what they're for. If you specifically need a web build, we've flagged which ones export to the browser, and you can go deeper in our best web game engines comparison.

Quick comparison ​

EngineLicenseLanguage2D / 3DWeb exportBest for
GodotMITGDScript, C#BothYes (GDScript)The all-round free engine
PhaserMITJavaScript2DYes2D web games
PixiJSMITJavaScript2DYesCustom 2D rendering
Three.jsMITJS / TS3DYesWeb 3D, max control
Babylon.jsApache 2.0JS / TS3DYesFull-featured web 3D
DefoldFree, source-availableLua2D / light 3DYesSmallest web builds
Excalibur.jsBSDTypeScript2DYesTypeScript 2D games
BevyMIT / Apache 2.0RustBothYes (Wasm)Rust, data-driven design
LÖVEzlibLua2DLimitedQuick 2D prototypes
Cocos CreatorMIT runtimeTypeScriptBothYesMini-games, Asian market
O3DEApache 2.0C++, Lua3DNoLarge-scale 3D, AAA scope

There's no single "best" open-source engine. The right one depends on 2D vs 3D, your language, and whether you're targeting the web.

Full 2D and 3D engines ​

Godot ​

Godot is the engine most people mean when they say "open-source game engine." It's MIT licensed, does both 2D and 3D, and has no fees or revenue caps of any kind. It ships small web builds (around 5 MB compressed) and, since 4.3, can export single-threaded for clean iOS and Safari support. The one web caveat is that C# projects can't export to the browser yet, only GDScript. For most teams leaving a proprietary engine, Godot is the closest all-round replacement. See Godot vs Unity for web games for the head to head.

Cocos Creator ​

Cocos Creator pairs a free editor with an open-source (MIT) runtime. It handles 2D and 3D, supports WebGL, WebGPU, and Wasm, and is especially strong for mini-game platforms like WeChat and TikTok where build size is critical. Builds land around 2 to 4 MB.

3D libraries and engines for the web ​

Three.js ​

Three.js is the most widely used 3D library on the web, MIT licensed, with a core around 150 KB. It's a rendering library rather than a full engine, so you add your own game systems or a framework on top. That's the trade-off: maximum control and the smallest footprint, in exchange for writing more yourself. It's the foundation we built Cinevva Engine on, layering the game systems back so you don't start from an empty canvas.

Babylon.js ​

Babylon.js is a full open-source 3D engine (Apache 2.0) with built-in physics, animation, a scene inspector, and strong WebGPU and WGSL support. Compared to Three.js it gives you more out of the box at a larger size. See Three.js vs Babylon.js for which fits your project.

2D frameworks ​

Phaser ​

Phaser is the most popular open-source HTML5 game framework, MIT licensed, with the biggest 2D web community and ecosystem. Builds are around 500 KB. If your game is 2D and you write JavaScript, it's hard to beat.

PixiJS ​

PixiJS is a fast 2D WebGL renderer (MIT), around 200 KB. Like Three.js for 3D, it's a renderer rather than a full engine, so you bring your own game logic. Pick it when you want custom 2D rendering and a tiny footprint.

Excalibur.js ​

Excalibur.js is a friendly, BSD-licensed 2D engine written in TypeScript, around 300 KB, with more built-in game features than a bare renderer. A good fit if you want types and a gentle on-ramp.

LÖVE (Love2D) ​

LÖVE is a long-running, zlib-licensed 2D framework scripted in Lua. It's beloved for fast prototyping and game jams on desktop. Web export exists through love.js but is limited, so treat LÖVE as a desktop-first tool.

Rust, C++, and large-scale engines ​

Bevy ​

Bevy is a modern, data-driven engine written in Rust, dual-licensed MIT and Apache 2.0. Its entity-component-system architecture is a big draw, and it compiles to WebAssembly for browser builds. It's younger than the others and moves fast, so expect breaking changes between versions, but it has strong momentum in 2026.

Open 3D Engine (O3DE) ​

O3DE is a Linux Foundation project (Apache 2.0) aimed at large-scale, high-fidelity 3D, backed by AWS and others. It's a serious, heavyweight engine for teams with AAA ambitions and the resources to match. It doesn't target the browser.

How to choose ​

  • Want one free engine for almost anything? Godot.
  • Building a 2D web game? Phaser, or PixiJS/Excalibur.js for custom rendering.
  • Building web 3D? Three.js for control and size, Babylon.js for batteries included.
  • Smallest possible web build? Defold.
  • Targeting mini-game platforms? Cocos Creator.
  • Love Rust and ECS? Bevy.
  • Large-scale, high-fidelity 3D? O3DE.

If the web is your target, every engine above except O3DE and (mostly) LÖVE can ship a browser build. For the full breakdown on web specifically, see the web game engines comparison and our guide to Unity alternatives for web games.

Common Questions ​

What is the best open-source game engine in 2026? ​

For most people it's Godot: MIT licensed, free with no revenue caps, and capable in both 2D and 3D with a clean web export. For 2D web specifically, Phaser is the most popular open-source pick, and for web 3D it's Three.js (a library) or Babylon.js (a full engine). The best choice depends on dimensions, language, and platform.

Is Godot really free, with no catch? ​

Yes. Godot is released under the MIT license, which means no fees, no royalties, no revenue thresholds, and no seats, ever. You can use it for commercial games and even modify the engine itself. The project is funded by donations and sponsorships, not by charging developers.

Are open-source game engines good enough for commercial games? ​

Yes. Plenty of commercially successful games ship on open-source engines, and open source means there's no revenue cap to worry about. The trade-offs are usually a smaller built-in asset marketplace and, for some engines, fewer turnkey features than a large proprietary engine. For web games in particular, open-source engines often produce smaller, faster builds.

Is Unity or Unreal open source? ​

No. Unity is closed-source and subscription-based. Unreal Engine is source-available (you can read and modify the code with an account) but it's not open source and uses a royalty model above a revenue threshold. If you specifically want an open-source engine, Godot is the closest equivalent to Unity, and our Unity alternatives guide covers the rest.

Which open-source game engine is best for the web? ​

Godot for an all-round 2D/3D engine, Phaser for 2D, and Three.js or Babylon.js for 3D. Defold ships the smallest web builds of any full engine. All of them are free and open source. Our web game engines comparison ranks them on build size, load time, and browser support.