head to head · open source
headroom vs CL4R1T4S
headroom has 78,773 GitHub stars, 6,155 forks, 643 open issues and last shipped yesterday. CL4R1T4S has 51,737 stars, 10,551 forks, 127 open issues and last shipped 1 months ago. headroom leads on adoption by 52% (78,773 vs 51,737 stars). headroom is written in Python under Apache-2.0; CL4R1T4S is written in various languages under AGPL-3.0. headroom has attracted 8% as many forks as stars, CL4R1T4S 20%. headroom was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (ai), 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
| headroom | CL4R1T4S | |
|---|---|---|
| GitHub stars | ★ 79K | ★ 52K |
| License | Apache-2.0 | AGPL-3.0 |
| Written in | Python | — |
| Last push | 2026-11-04 | 2026-09-22 |
| Forks | ⑂ 6.2K | ⑂ 11K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick headroom if
- You weight community size — 79K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick CL4R1T4S if
- You want the CL4R1T4S feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- You evaluated both and CL4R1T4S fits your workflow better
About headroom
Quickstart · Install · Proof · Agents · Docs · Discord · llms.txt AI agents / LLMs: read /llms.txt here, or fetch the live index · full docs blob . Headroom compresses everything your AI agent reads — tool outputs, logs, RAG chunks, files, and conversation history — before it reaches the LLM. Same answers, fraction of the tokens. Compression runs on your machine; no prompt or file content is sent anywhere to be compressed. 10,144 → 1,260 tokens. The same FATAL found. What it does Library — compress(messages) in Python or TypeScript, inline in any app. Proxy — headroom proxy port 8787 , zero code changes, any…
read the full headroom overview →
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 →
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Frequently asked questions
Is headroom or CL4R1T4S more popular?
headroom has 78,773 GitHub stars and CL4R1T4S has 51,737. headroom has the larger community by that measure.
Are headroom and CL4R1T4S free?
Both are open source. headroom is licensed under Apache-2.0 and CL4R1T4S under AGPL-3.0. Neither carries a licence fee.
What is the difference between headroom and CL4R1T4S?
headroom is written in Python and CL4R1T4S in various languages. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, headroom or CL4R1T4S?
Choose headroom if you want the larger community (78,773 stars) or its Apache-2.0 licence terms. Choose CL4R1T4S if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.