head to head · open source
cobalt vs Spark
cobalt has 43,461 GitHub stars, 3,812 forks, 269 open issues and last shipped 6 months ago. Spark has 604 stars, 445 forks, 7 open issues and last shipped 5 days ago. cobalt leads on adoption by 7,096% (43,461 vs 604 stars). cobalt is written in Svelte under AGPL-3.0; Spark is written in Java under Apache-2.0. cobalt has attracted 9% as many forks as stars, Spark 74%. Spark 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 | Spark | |
|---|---|---|
| GitHub stars | ★ 43K | ★ 604 |
| License | AGPL-3.0 | Apache-2.0 |
| Written in | Svelte | Java |
| Last push | 2026-04-06 | 2026-09-13 |
| Forks | ⑂ 3.8K | ⑂ 445 |
| 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 Spark if
- You want the Spark feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and Spark 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 Spark
Spark ===== [Spark] is an Open Source, cross platform IM client optimized for businesses and organizations. Group Chat In line Spell Checking End to end (E2E) Message Encryption with OTR. Tabbed Conversations File Transfer Screen Capture Sharing Message translations. Combined with the [Openfire] server, [Spark] is the easiest and best alternative to using unsecure public IM networks. [Spark] an [Ignite Realtime] community project. Resources Translation: Documentation: Community: Bug Tracker: Nightly Builds: XMPP compliance: Install Download the last release from the GitHub releases page or nightly build with the …
read the full Spark overview →
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Frequently asked questions
Is cobalt or Spark more popular?
cobalt has 43,461 GitHub stars and Spark has 604. cobalt has the larger community by that measure.
Are cobalt and Spark free?
Both are open source. cobalt is licensed under AGPL-3.0 and Spark under Apache-2.0. Neither carries a licence fee.
What is the difference between cobalt and Spark?
cobalt is written in Svelte and Spark in Java. 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 Spark?
Choose cobalt if you want the larger community (43,461 stars) or its AGPL-3.0 licence terms. Choose Spark if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.