head to head · open source
effect vs cost-xray
effect has 16,138 GitHub stars, 752 forks, 253 open issues and last shipped today. cost-xray has 2,107 stars, 214 forks, 13 open issues and last shipped 19 days ago. effect leads on adoption by 666% (16,138 vs 2,107 stars). effect is written in TypeScript under MIT; cost-xray is written in Python under MIT. effect has attracted 5% as many forks as stars, cost-xray 10%. effect was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (observability), 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
| effect | cost-xray | |
|---|---|---|
| GitHub stars | ★ 16K | ★ 2.1K |
| License | MIT | MIT |
| Written in | TypeScript | Python |
| Last push | 2026-09-20 | 2026-09-01 |
| Forks | ⑂ 752 | ⑂ 214 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick effect if
- You weight community size — 16K stars and counting
- You want the MIT license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick cost-xray if
- You want the cost-xray feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Python
- You evaluated both and cost-xray fits your workflow better
About effect
Effect is a TypeScript library for building robust, maintainable, type safe, and production grade applications. It lives in the TypeScript and JavaScript ecosystem, distributed as the core effect package alongside a monorepo of integration packages that extend it. The project is MIT licensed, has been developed for roughly seven years, and currently ships Effect V4 as a release candidate, with the main branch holding v4 development and the v3 branch retaining the previous line.
read the full effect overview →
About cost-xray
cost xray is an MIT licensed open source observability proxy for Claude Code and Codex that captures the API traffic those agents actually send and attributes every token and dollar back to the system prompts, tool schemas, MCP blocks, tool results, cache reads and writes, and thinking blocks that produced them.
read the full cost-xray overview →
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Frequently asked questions
Is effect or cost-xray more popular?
effect has 16,138 GitHub stars and cost-xray has 2,107. effect has the larger community by that measure.
Are effect and cost-xray free?
Both are open source. effect is licensed under MIT and cost-xray under MIT. Neither carries a licence fee.
What is the difference between effect and cost-xray?
effect is written in TypeScript and cost-xray in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, effect or cost-xray?
Choose effect if you want the larger community (16,138 stars) or its MIT licence terms. Choose cost-xray if its feature set, stack or MIT licence fits better. Both are self-hostable.