AI Prompt Checker

Are the instructions unambiguous, or open to interpretation?

Is the output format and the constraint set actually defined?

Are the critical instructions where the model reads them, not buried?

Does it handle malformed, ambiguous, or malicious input?

01

Paste your prompt. No login, no API key, nothing to install.

02

Get a 0 to 100 score across four dimensions, plus the critical issues found.

03

Fix them, re-check, and watch the score climb. The score is deterministic.

What is an AI prompt checker?

It analyzes your prompt for the weaknesses that make LLM output inconsistent: ambiguous instructions, missing output format, conflicting rules, and no handling for edge cases. It works like a linter for natural-language instructions. You paste the prompt, and it scores the structure and shows what to fix before you send it to GPT-4o, Claude, or Gemini.

Is it free? Do I need an API key or login?

Your first check is free with no login and no API key. A free account (no credit card) unlocks the full diagnosis, the corrected version of your prompt, and 3 evaluations per month. It runs in the browser, nothing to install.

What do I get if I create a free account?

The free check shows your score, the four-dimension breakdown, and the top issues found. A free account (no card) gives you 3 checks a month and saves your prompts with version history, so you can re-check and watch the score climb as you fix them. The full list of issues, the specific recommendations, and the corrected version of your prompt are unlocked on the Basic plan.

What is the difference between a prompt checker and a prompt tester?

A checker analyzes the prompt itself (structure, clarity, completeness) and scores it before you run it, the way a linter reviews code without executing it. A tester runs the prompt against a model and checks the outputs. Checking is faster and catches structural problems up front; testing verifies behavior against real inputs.

Which models does it work for?

It is model-agnostic. It evaluates prompt structure, which applies whether you run on GPT-4o, Claude, Gemini, or Llama. The same clarity, specificity, structure, and robustness principles govern output quality across every model.

Do you store my prompt?

No prompt content is stored. The checker returns a score and diagnosis and keeps nothing.