head to head · open source
cobalt vs FluidFramework
cobalt has 43,316 GitHub stars, 3,798 forks, 269 open issues and last shipped 6 months ago. FluidFramework has 4,946 stars, 586 forks, 207 open issues and last shipped yesterday. cobalt leads on adoption by 776% (43,316 vs 4,946 stars). cobalt is written in Svelte under AGPL-3.0; FluidFramework is written in TypeScript under MIT. cobalt has attracted 9% as many forks as stars, FluidFramework 12%. FluidFramework was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (collaboration), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| cobalt | FluidFramework | |
|---|---|---|
| GitHub stars | ★ 43K | ★ 4.9K |
| License | AGPL-3.0 | MIT |
| Written in | Svelte | TypeScript |
| Last push | 2026-04-06 | 2026-09-17 |
| Forks | ⑂ 3.8K | ⑂ 586 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick cobalt if
- You weight community size — 43K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Svelte
- You value the larger contributor base for long-term maintenance
pick FluidFramework if
- You want the FluidFramework feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and FluidFramework fits your workflow better
About cobalt
cobalt is a media downloader built around a single promise: paste a link, get the file, move on. It is a monorepo containing the source for an API, a web frontend, and related packages, written primarily in Svelte and TypeScript. The project lives in the modern web and JavaScript ecosystem, and its public surface is hosted at cobalt.tools, while the full codebase is published under the AGPL 3.0 license.
read the full cobalt overview →
About FluidFramework
FluidFramework is an MIT licensed TypeScript library from Microsoft for building distributed, real time collaborative web applications in JavaScript or TypeScript, aimed at developers who need shared, synchronized state across many clients without assembling that synchronization layer themselves.
read the full FluidFramework overview →
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Frequently asked questions
Is cobalt or FluidFramework more popular?
cobalt has 43,316 GitHub stars and FluidFramework has 4,946. cobalt has the larger community by that measure.
Are cobalt and FluidFramework free?
Both are open source. cobalt is licensed under AGPL-3.0 and FluidFramework under MIT. Neither carries a licence fee.
What is the difference between cobalt and FluidFramework?
cobalt is written in Svelte and FluidFramework in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, cobalt or FluidFramework?
Choose cobalt if you want the larger community (43,316 stars) or its AGPL-3.0 licence terms. Choose FluidFramework if its feature set, stack or MIT licence fits better. Both are self-hostable.