System Prompt Linter
Lint system prompts in your browser: contradictions, vague wording, missing format spec, wasted tokens. Rule-based, not AI.
It checks your AI instructions for common mistakes.
What this tool does
A system prompt can contain conflicting rules, vague phrases, repeated text, or an unclear output format. This linter catches mechanical problems with fixed rules. No model reads your prompt.
- Find instructions that say both "always" and "never"
- Spot vague wording, duplicate sentences, and missing output formats
- Review sensitive prompts without sending them to another AI service
Not stored in the URL or sent anywhere — linting runs locally in your browser.
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Rule-based checks only — no LLM reads your prompt. Good for catching obvious mistakes, not for judging whether instructions will work in production.
System prompts are code you never typecheck. This linter runs simple
heuristics: length bounds, keyword contradictions, vague phrases,
missing output format, politeness filler, ALL CAPS ratio, duplicate
sentences, unclosed ``` fences, and
multiple "you are…" personas.
It is not an AI review and it cannot know your product. A clean lint pass does not mean the prompt works — it means you avoided a few common footguns. Always test on real inputs.
Token estimate uses ~4 characters per token — close enough for English prose, wrong for code-heavy prompts. Treat it as a ballpark.