head to head · open source
CL4R1T4S vs promptfoo
CL4R1T4S has 50,059 GitHub stars, 10,280 forks, 127 open issues and last shipped 10 days ago. promptfoo has 25,297 stars, 2,344 forks, 651 open issues and last shipped today. CL4R1T4S leads on adoption by 98% (50,059 vs 25,297 stars). CL4R1T4S is written in various languages under AGPL-3.0; promptfoo is written in TypeScript under MIT. CL4R1T4S has attracted 21% as many forks as stars, promptfoo 9%. promptfoo was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (prompt-engineering), 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
| CL4R1T4S | promptfoo | |
|---|---|---|
| GitHub stars | ★ 50K | ★ 25K |
| License | AGPL-3.0 | MIT |
| Written in | — | TypeScript |
| Last push | 2026-09-10 | 2026-09-20 |
| Forks | ⑂ 10K | ⑂ 2.3K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick CL4R1T4S if
- You weight community size — 50K stars and counting
- You want the AGPL-3.0 license terms
- You value the larger contributor base for long-term maintenance
pick promptfoo if
- You want the promptfoo feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches TypeScript
- You evaluated both and promptfoo fits your workflow better
About CL4R1T4S
CL4R1T4S is an AGPL 3.0 repository of full extracted system prompts, guidelines and tools from the major AI models and agents — ChatGPT, Claude, Gemini, Grok, Perplexity, Cursor, Lovable, Replit and more — for anyone who wants to know what instructions sit behind the AI systems they use.
read the full CL4R1T4S overview →
About promptfoo
Promptfoo is an open source command line tool and TypeScript library for evaluating and red teaming large language model applications, aimed at developers, AI engineers, and security teams who need measurable evidence that a prompt, agent, or retrieval augmented generation pipeline behaves correctly and safely before it reaches users.
read the full promptfoo overview →
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Frequently asked questions
Is CL4R1T4S or promptfoo more popular?
CL4R1T4S has 50,059 GitHub stars and promptfoo has 25,297. CL4R1T4S has the larger community by that measure.
Are CL4R1T4S and promptfoo free?
Both are open source. CL4R1T4S is licensed under AGPL-3.0 and promptfoo under MIT. Neither carries a licence fee.
What is the difference between CL4R1T4S and promptfoo?
CL4R1T4S is written in various languages and promptfoo 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, CL4R1T4S or promptfoo?
Choose CL4R1T4S if you want the larger community (50,059 stars) or its AGPL-3.0 licence terms. Choose promptfoo if its feature set, stack or MIT licence fits better. Both are self-hostable.