When to use it
Use That Open Engine when…
01You must interoperate with IFC and/or your own schema (schema-agnostic, no vendor lock-in).
02You’re building an AECO product (a startup or a new module) and need full control with no per-seat fees.
03You want to own custom review and QA workflows end to end (issues, views, checks).
04You need to embed an open BIM viewer into an existing web app (SaaS, CDE, portal, intranet).
05You handle very large models and need fast, reliable in-browser streaming.
06You’re moving desktop workflows to the web and want a modern, cloud-ready UX.
07You require a 100% open-source (MIT) engine for procurement or compliance, or to avoid licensing risk.
Why it's fast and reliable
Built on three.js. Based on Fragments.
Built on three.jsThe most widely used 3D JS library: mature rendering, huge community, easier hiring.
Web-first architectureDesigned for browsers and the cloud; easy to embed in modern stacks.
MIT licenseFull freedom to use, modify and ship commercial products.
Based on FragmentsFast at scale, editable by design, schema-agnostic and future-proof.
Fragments-ready pipelinesBinary, lightweight, deduplicated data for streaming at scale.
Progressive loadingRender useful views immediately; fetch the rest on demand.
GPU-efficient renderingInstancing and batching for repeated elements and huge scenes.
Smart culling & indexingResponsive selection, isolation and filtering on big models.
Versioned, predictable APIsClear behaviour that won’t break between releases.
Stable IDsDeterministic selections and consistent references across sessions.
Worker isolationHeavy tasks off the main thread keep the UI smooth.
Graceful degradationSensible fallbacks when a capability isn’t available.
Capabilities
Everything a BIM web app needs.
Review toolsClipping and sections, saved views, issues and viewpoints, BCF support.
Embedding & extensibilityIntegrate into your stack and add custom logic.
Rendering & interactionNavigation, selection, isolate and hide, visibility control.
Data accessRead and query properties, map metadata, fast filtering.
UI blocksLists, trees, tables, 2D-in-3D markers.
ValidationRequirement and spec checks based on the IDS standard.
MIT license Zero cost, real freedom.
Free to use: no fees, including commercial products. Free to modify and ship: change the code and distribute your apps, paid or free. No copyleft: you don't have to open-source your app. Only requirement: keep the copyright and MIT notice in redistributed code. Host anywhere, integrate with your stack.
Quickstart Three steps.
01Install That Open Engine
02Load a Fragments model
03Render and interact (select, isolate, clip, measure)
Questions
Do I have to pay?
No. That Open Engine is open source and free, under the MIT license. There is no license fee, no per-user cost and no paid tiers.
Can I use it in commercial products?
Yes. The MIT license allows commercial use at no cost, including in products you sell. You owe us nothing for it.
Must I open-source my app?
No. MIT is not a copyleft license: your code stays yours and you can keep it closed. The only requirement is to keep the copyright and MIT notice in any of our code you redistribute.
What's the catch?
There is no catch. The engine is MIT-licensed and free. We make our money from That Open Platform and from professional services, not from the libraries. Read the license.