head to head · open source
effect vs pup
effect has 16,138 GitHub stars, 752 forks, 253 open issues and last shipped today. pup has 1,014 stars, 121 forks, 12 open issues and last shipped 2 days ago. effect leads on adoption by 1,492% (16,138 vs 1,014 stars). effect is written in TypeScript under MIT; pup is written in Rust under Apache-2.0. effect has attracted 5% as many forks as stars, pup 12%. effect was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (cli, 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 | pup | |
|---|---|---|
| GitHub stars | ★ 16K | ★ 1.0K |
| License | MIT | Apache-2.0 |
| Written in | TypeScript | Rust |
| Last push | 2026-09-20 | 2026-09-18 |
| Forks | ⑂ 752 | ⑂ 121 |
| 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 pup if
- You want the pup feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and pup 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 pup
Pup is an Apache 2.0 licensed, Rust written command line client from Datadog that exposes more than 200 commands across over 33 Datadog product domains, letting AI agents and the humans who supervise them query observability data from a terminal.
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Frequently asked questions
Is effect or pup more popular?
effect has 16,138 GitHub stars and pup has 1,014. effect has the larger community by that measure.
Are effect and pup free?
Both are open source. effect is licensed under MIT and pup under Apache-2.0. Neither carries a licence fee.
What is the difference between effect and pup?
effect is written in TypeScript and pup in Rust. 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 pup?
Choose effect if you want the larger community (16,138 stars) or its MIT licence terms. Choose pup if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.