head to head · open source
reaction vs mercur
reaction has 12,399 GitHub stars, 2,176 forks, 96 open issues and last shipped 7 months ago. mercur has 1,768 stars, 444 forks, 4 open issues and last shipped yesterday. reaction leads on adoption by 601% (12,399 vs 1,768 stars). reaction is written in JavaScript under GPL-3.0; mercur is written in TypeScript under MIT. reaction has attracted 18% as many forks as stars, mercur 25%. mercur was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (ecommerce, marketplace), 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
| reaction | mercur | |
|---|---|---|
| GitHub stars | ★ 12K | ★ 1.8K |
| License | GPL-3.0 | MIT |
| Written in | JavaScript | TypeScript |
| Last push | 2026-03-01 | 2026-09-17 |
| Forks | ⑂ 2.2K | ⑂ 444 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick reaction if
- You weight community size — 12K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches JavaScript
- You value the larger contributor base for long-term maintenance
pick mercur if
- You want the mercur feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and mercur fits your workflow better
About reaction
Mailchimp Open Commerce, formerly Reaction Commerce, is an API first, headless commerce platform built on Node.js, MongoDB, and GraphQL for development teams that want to run a custom storefront, marketplace, or multi shop operation on their own infrastructure — and the project has been discontinued.
read the full reaction overview →
About mercur
Mercur is an open source, headless marketplace platform written in TypeScript and built on Medusa.js. It provides a storefront, vendor panel, admin console, and integrations as modular applications that communicate with a commerce core over APIs. The project targets multi vendor commerce, where several sellers list offers on one marketplace, and it positions itself as an alternative to Mirakl.
read the full mercur overview →
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Frequently asked questions
Is reaction or mercur more popular?
reaction has 12,399 GitHub stars and mercur has 1,768. reaction has the larger community by that measure.
Are reaction and mercur free?
Both are open source. reaction is licensed under GPL-3.0 and mercur under MIT. Neither carries a licence fee.
What is the difference between reaction and mercur?
reaction is written in JavaScript and mercur 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, reaction or mercur?
Choose reaction if you want the larger community (12,399 stars) or its GPL-3.0 licence terms. Choose mercur if its feature set, stack or MIT licence fits better. Both are self-hostable.