This is a public, plain-language statement of Estella's licensing and business model. We want there to be zero ambiguity about what you can do with Estella and how the project pays for itself.
- The engine is licensed under Apache-2.0. Use it for anything, including commercial games and commercial products, free of charge. No royalties, no seat fees, no revenue thresholds, no "free for indies, paid for studios" tier.
- The engine is open and stays open. The runtime, the SDK, the asset pipeline, the build CLI, the runtime loader, the project templates and the plugin API are all Apache-2.0. Everything needed to build, run and ship a game is here.
- The visual editor is not open source. It is a separate product, developed in a private repository. This is a change from how Estella shipped through v0.55.0 — see What changed with the editor below, which says plainly what we promised before and what we are doing instead.
- We fund the project from things built around the engine, not from the engine itself — sponsorship, optional hosted/"pro" add-ons, a marketplace, and paid support. Every one of those is optional; none of them gate the open-source engine.
- One caveat that is not ours to waive: the bundled Spine Runtimes are not open source. If you ship a game using Estella's Spine integration, you need a Spine license from Esoteric Software. See NOTICE.
For a short window (v0.13.0, June 2026) Estella shipped under the PolyForm Noncommercial License, with a separate paid commercial license. We reverted that in v0.14.0. The honest reasons:
- A noncommercial-only engine can't be adopted by the people who would actually build on it — studios, freelancers, and anyone shipping a paid game. Adoption is the foundation everything else here depends on.
- "Free for noncommercial, pay us for commercial" creates friction and uncertainty exactly when a developer is deciding whether to commit. That uncertainty is more expensive to the project than the license revenue it might have produced.
- We'd rather compete on being genuinely good and genuinely open than on license enforcement.
We chose Apache-2.0 (over MIT) because it adds an explicit patent grant and a clear trademark boundary, which protect both users and the project, while still being fully permissive and commercial-friendly. It is also compatible with the permissive licenses of our bundled dependencies.
The Apache-2.0 grant is irrevocable for the code released under it. We can't take back the rights you already have. The engine will remain under a permissive OSI-approved license. If governance ever moves (for example, to a foundation), it will only move in a direction that keeps the engine open.
The limit is now explicit, because the previous version of this promise was not: it covers the engine. The editor moved out from under it, which is exactly the kind of move this section used to be read as ruling out.
Through v0.55.0 the visual editor shipped in this repository under Apache-2.0, and this document said the editor was part of what stays open, under a heading that promised no rug-pull. That is no longer true, and we are not going to pretend it was never said. From the next release the editor is developed in a private repository and is a separate product.
Two things about that are worth stating precisely:
- The Apache-2.0 grant on the editor code already released is irrevocable. Every version up to and including v0.55.0 remains Apache-2.0 for everyone who has it. You may use, modify, fork and redistribute that code under those terms. We cannot take that back and are not trying to.
- The engine's Apache-2.0 grant is unchanged and is what the rest of this document commits to. The engine is not being made worse to push the editor: the split moved the engine's own verification INTO the engine, and the open repo now runs its own renderer gates rather than borrowing the editor's host.
If you were relying on the editor being open, that is a reasonable thing to have relied on, and we would rather say so here than let you find out from a changelog.
Everything needed to build and ship a game is Apache-2.0 and lives in this repo:
- the C++/WebAssembly engine runtime and renderer,
- the TypeScript SDK (
esengine) and the web loader (@esengine/web-loader), - the asset pipeline and the build/CLI tooling,
- the project templates a new game starts from,
- the editor plugin API (
editor-api/), so a plugin author needs no private code, - documentation and examples.
We will not move a feature from this list behind a paywall. New core capabilities land here, openly.
Four pillars, all built alongside the open engine rather than by restricting it:
Recurring sponsorship (e.g. GitHub Sponsors / OpenCollective) and one-off donations from individuals and companies that depend on Estella. Sponsors may get recognition and a louder voice on the roadmap — never exclusive access to core features.
The visual editor is a separate product built on top of the open engine, as are things like team collaboration, a managed build-and-publish pipeline, or a hosted build service. The open-source engine is fully usable, self-hostable, and shippable without any of them: the SDK, the CLI and the templates are a complete path from an empty directory to a shipped game on every target Estella supports.
A place to buy and sell assets, templates, and plugins, with the project taking a small cut. The engine and the ability to load third-party content stay free; the marketplace is an optional storefront.
Paid priority support, training, and custom development for studios that want a direct line or specific work done. The community gets best-effort support for free via Discord/issues/QQ.
- The core engine stays Apache-2.0 and stays feature-complete on its own — a game can be built, run, packaged and shipped from this repository alone.
- Paid offerings are additive and optional — they never remove or gate functionality that is in the open-source engine today.
- We won't make the open build deliberately worse to push the paid one.
- When we change a licensing commitment, we say so where the old one was written, rather than quietly editing it away.
- Trademarks: Apache-2.0 covers the code, not the "Estella"/"ESEngine" names and logos. Please say your project "uses Estella," but don't ship a fork under the Estella name or imply official endorsement.
- Attribution: if you redistribute Estella (including inside a closed-source product, which Apache-2.0 allows), keep the LICENSE and NOTICE and mark changed files — see NOTICE and Apache-2.0 §4.
These funding pillars describe the direction, not a finished storefront — most are not live yet. What is committed today is the engine's licensing: Apache-2.0, free for commercial use. As paid offerings come online they'll be announced here and in the CHANGELOG.
Questions about licensing, sponsorship, or commercial support: 359807859@qq.com · Discord · QQ Group 481923584.