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System prompt linter

Check a system prompt with fixed rules for contradictions, vague wording, placeholders, credentials and missing output contracts, scored out of 100.

Paste a system prompt, then press Check prompt.

Nothing here is sent to any model; every rule is plain JavaScript running in this tab, which is what makes the score usable as a review gate between prompt versions. Know what the rules cannot see: contradictions only register when both sides share wording, so "always refund" against "reject every refund request" passes; legitimate exceptions are flagged until you merge them into one rule; and the score compares versions of the same prompt, not different prompts against each other.
OptionsCheck prompt

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Canonical HTML: https://nutter.tools/ai/system-prompt-linter
Markdown version: https://nutter.tools/ai/system-prompt-linter.md
Plain-text version: https://nutter.tools/ai/system-prompt-linter.txt
Agent index: https://nutter.tools/llms.txt