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Game Development · head to head

Flax Engine vs Three.js

Flax Engine logo

Flax Engine

Game Development

Modern 3D game engine with visual editor

From
Free
Rated
-
Full reviewWebsite
Three.js logo

Three.js

AR VR

JavaScript 3D library for WebGL and WebXR

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flax Engine flax charges a 4% royalty on game earnings above $250,000, assessed per calendar quarter; Three.js forward rendering pipeline only, no deferred rendering support
  • They diverge on capability: Flax Engine covers 3D graphics rendering, Three.js covers WebGL rendering.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Flax Engine and Three.js actually diverge.

Attributes where Flax Engine and Three.js differ
AttributeFlax EngineThree.js
PlatformsWindows, Linux, Playstation, XboxWeb, macOS, Windows, Linux, iOS, Android
CategoryGame DevelopmentAR VR
Founded20172010

Identical on both: starting price (Free), pricing model (free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Flax Engine

  • 3D graphics rendering
  • Visual editor
  • C# scripting
  • Physics engine
  • Audio system
  • Particle effects
  • Skeletal animation
  • Material system

Only in Three.js

  • WebGL rendering
  • Scene graph
  • Materials system
  • Animation system
  • WebXR
  • Post-processing
  • Physics
  • Loaders

What people use each for

The jobs each tool is most often brought in to do.

Flax Engine

  • Building 3D games in C# and C++ with full engine source accessnot Three.js
  • Multi-platform deployment from one editornot Three.js
  • Prototyping with the bundled Flax Samples projectsnot Three.js

Three.js

  • VR Gamingnot Flax Engine
  • AR Marketingnot Flax Engine
  • Virtual Trainingnot Flax Engine
  • 3D Visualizationnot Flax Engine
  • Immersive Experiencesnot Flax Engine

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Flax Engine

  • Flax charges a 4% royalty on game earnings above $250,000, assessed per calendar quarter
  • Free use is granted for non-commercial or educational usage; commercial releases fall under the royalty
  • Users must accept the Flax Engine End-User License Agreement before using the engine or its tools, so it is not an OSI open source licence despite the source being on GitHub
  • Non-game uses such as in-house tools or SaaS products need a custom licence negotiated with the vendor, and no rate card is published for per-seat or flat-fee options

Three.js

  • Forward rendering pipeline only, no deferred rendering support
  • No built-in collision detection or spatial indexing, requiring external physics libraries
  • WebGL dependency means no support for non-WebGL environments

Pricing, plan by plan

Flax Engine

Free
  • FreeFree
    • Full engine
    • Visual editor
    • C# scripting

Three.js

Free
  • FreeFree
    • Full library
    • WebXR module
    • Examples

Which should you pick?

Choose Flax Engine if

  • You need 3d graphics rendering.
  • You want to start without paying.
  • You work on Windows, Linux, Playstation, Xbox.
  • You also want visual editor.
Flax Engine review

Choose Three.js if

  • You need webgl rendering.
  • You want to start without paying.
  • You work on Web, macOS, Windows, Linux, iOS, Android.
  • You also want scene graph.
Three.js review

Questions people ask

Is Flax Engine or Three.js better?
Neither clearly leads. Flax Engine starts at Free and Three.js at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flax Engine or Three.js?
Flax Engine starts at Free and Three.js at Free.
Does Flax Engine or Three.js run on more platforms?
Flax Engine runs on Windows, Linux, Playstation, Xbox. Three.js runs on Web, macOS, Windows, Linux, iOS, Android.
Can I use Flax Engine for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flax Engine best used for?
Flax Engine is most often used for building 3d games in c# and c++ with full engine source access, multi-platform deployment from one editor, prototyping with the bundled flax samples projects. Of those, building 3d games in c# and c++ with full engine source access and multi-platform deployment from one editor are not what Three.js is typically brought in for.
What can Flax Engine do that Three.js cannot?
Flax Engine covers 3D graphics rendering, Visual editor, C# scripting, Physics engine. Three.js covers WebGL rendering, Scene graph, Materials system, Animation system.

Answered from the vendors’ own pages

Flax Engine: How much does Flax Engine cost?

Flax Engine is free during development. Once you ship a game commercially, you pay a 4% royalty on earnings only if your quarterly revenue exceeds $250,000 in a calendar quarter. Below that threshold, there is no royalty charge.

Source
Three.js: Is Three.js free to use?

Yes. Three.js is released under the MIT license, an open-source license that permits unlimited commercial and personal use with no licensing fees.

Source
Flax Engine: Is Flax Engine free for educational and uncommercial projects?

Yes. Flax Engine is free for uncommercial or educational usage. You only pay royalties when you release a commercial product that exceeds the $250,000 quarterly earnings threshold.

Source
Three.js: Does Three.js include physics simulation?

No. Three.js is a rendering library only. Physics, collision detection, and spatial indexing must be implemented with external libraries like Rapier, Ammo, or JoltPhysics.

Source
Flax Engine: Do all Flax Engine users get access to the same features?

Yes. There is one version of Flax Engine. All users get full engine access with all features, supported platforms, complete editor source code on GitHub, sample projects, and free deployment to all supported platforms.

Source
Three.js: Can I use Three.js for offline development?

Yes. Local development requires a local web server for CORS compliance. You can use npm with a build tool like Vite, or run a local Python server for development.

Source
Flax Engine: Does Flax Engine offer custom licensing options?

Yes. For non-game industries or specific needs, Flax Engine offers custom licensing including per-seat licensing (monthly or yearly) or flat fees per project, with pricing based on team size and product use case.

Source
Three.js: Does Three.js support WebXR for VR/AR?

Yes. Three.js documentation includes WebXR APIs for building VR and AR experiences in web browsers.

Source
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