head to head · open source
SkillSpector vs arcjet-js
SkillSpector has 17,624 GitHub stars, 1,504 forks, 136 open issues and last shipped yesterday. arcjet-js has 683 stars, 31 forks, 11 open issues and last shipped yesterday. SkillSpector leads on adoption by 2,480% (17,624 vs 683 stars). SkillSpector is written in Python under Apache-2.0; arcjet-js is written in TypeScript under Apache-2.0. SkillSpector has attracted 9% as many forks as stars, arcjet-js 5%. SkillSpector was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (agent-security, ai-security, mcp), 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
| SkillSpector | arcjet-js | |
|---|---|---|
| GitHub stars | ★ 18K | ★ 683 |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | TypeScript |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 1.5K | ⑂ 31 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick SkillSpector if
- You weight community size — 18K 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 arcjet-js if
- You want the arcjet-js feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches TypeScript
- You evaluated both and arcjet-js fits your workflow better
About SkillSpector
SkillSpector is an open source security scanner for AI agent skills that detects vulnerabilities, malicious patterns, prompt injection, data exfiltration, and supply chain risk in Claude Code, Codex CLI, Gemini CLI, and MCP skills before they are installed — built for developers who install agent skills and for security teams that vet or publish them.
read the full SkillSpector overview →
About arcjet-js
Arcjet for JavaScript is an Apache 2.0 TypeScript monorepo of runtime security packages that developers call directly inside JavaScript and TypeScript applications, so AI features and agents can detect prompt injection, authorize tool calls, redact sensitive data, and block bots and abuse before an action runs.
read the full arcjet-js overview →
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Frequently asked questions
Is SkillSpector or arcjet-js more popular?
SkillSpector has 17,624 GitHub stars and arcjet-js has 683. SkillSpector has the larger community by that measure.
Are SkillSpector and arcjet-js free?
Both are open source. SkillSpector is licensed under Apache-2.0 and arcjet-js under Apache-2.0. Neither carries a licence fee.
What is the difference between SkillSpector and arcjet-js?
SkillSpector is written in Python and arcjet-js 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, SkillSpector or arcjet-js?
Choose SkillSpector if you want the larger community (17,624 stars) or its Apache-2.0 licence terms. Choose arcjet-js if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.