head to head · open source
CL4R1T4S vs promptfoo
CL4R1T4S has 51,737 GitHub stars, 10,551 forks, 127 open issues and last shipped 1 months ago. promptfoo has 26,809 stars, 2,648 forks, 651 open issues and last shipped yesterday. CL4R1T4S leads on adoption by 93% (51,737 vs 26,809 stars). CL4R1T4S is written in various languages under AGPL-3.0; promptfoo is written in TypeScript under MIT. CL4R1T4S has attracted 20% as many forks as stars, promptfoo 10%. 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 | ★ 52K | ★ 27K |
| License | AGPL-3.0 | MIT |
| Written in | — | TypeScript |
| Last push | 2026-09-22 | 2026-11-04 |
| Forks | ⑂ 11K | ⑂ 2.6K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick CL4R1T4S if
- You weight community size — 52K 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 AI SYSTEMS TRANSPARENCY AND OBSERVABILITY FOR ALL! Full extracted system prompts, guidelines, and tools from OpenAI, Google, Anthropic, xAI, Perplexity, Cursor, Windsurf, Devin, Manus, Replit, and more – virtually all major AI models + agents! 📌 Why This Exists "In order to trust the output, one must understand the input." AI labs shape how models behave using massive, unseen prompt scaffolds. Because AI is a trusted external intelligence layer for a growing number of humans, these hidden instructions can affect the perceptions and behavior of the public. These prompts define: What AIs can’t say What…
read the full CL4R1T4S overview →
About promptfoo
Promptfoo: LLM evals & red teaming promptfoo is a CLI and library for evaluating and red teaming LLM apps. Stop the trial and error approach start shipping secure, reliable AI apps. Website · Getting Started · Red Teaming · Documentation · Discord Promptfoo is now part of OpenAI. Promptfoo remains open source and MIT licensed. Read the company update. Quick Start Requires Node.js =22.22.0 for npm and npx usage. Node.js 24 LTS is recommended; see the runtime support guide. Also available via brew install promptfoo and pip install promptfoo . You can also use npx promptfoo@latest to run any command without…
read the full promptfoo overview →
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Frequently asked questions
Is CL4R1T4S or promptfoo more popular?
CL4R1T4S has 51,737 GitHub stars and promptfoo has 26,809. 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 (51,737 stars) or its AGPL-3.0 licence terms. Choose promptfoo if its feature set, stack or MIT licence fits better. Both are self-hostable.