Free · nothing is transmitted

Check your prompt.

Two questions about anything you are about to paste into ChatGPT, Claude, Gemini or Grok. What personal or company data are you sending with it? And is the prompt actually built to work, or is it filler?

This page reads your prompt in your own browser and sends nothing anywhere. That is the point: you should not have to hand a prompt to a third service to find out whether it is safe to hand to a third service.

Paste the prompt

Paste it exactly as you would send it, filled-in data and all. Nothing leaves this page.

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What this is not

  • Not a guarantee. A prompt that passes every check can still produce a bad answer, and one that fails them can produce a good one.
  • Not a data-loss-prevention product. It finds patterns it knows about. A name, a diagnosis or a trade secret written in plain prose has no pattern, and it will not be found.
  • Not a compliance tool. It does not make you compliant with any regulation, and it does not certify anything.
  • Not connected to any model. It never calls one, which is why it cannot tell you what an answer would look like.

Why these checks and not others

Most published prompt advice is folklore. These checks are limited to things with either a measured effect in published research, or a plain mechanical justification. Where the evidence is thin, it says so on the check itself rather than in a footnote.

Formatting matters more than wording. Sclar, Choi, Tsvetkov and Suhr found performance differences of up to 76 accuracy points on LLaMA-2-13B from meaning-preserving changes to prompt format alone, and the sensitivity survived larger models, more examples and instruction tuning. arXiv:2310.11324, ICLR 2024.

Personas do not improve accuracy. Zheng, Pei, Logeswaran, Lee and Jurgens tested 162 personas across four model families on 2,410 factual questions and found that adding a persona to a system prompt does not improve performance, and that picking the best persona is no better than random. arXiv:2311.10054, Findings of EMNLP 2024.

Step-by-step helps on maths, not on everything. Sprague and colleagues meta-analysed over a hundred papers and ran 20 datasets across 14 models, finding chain-of-thought helps mainly on mathematical and symbolic reasoning, with much smaller gains elsewhere. arXiv:2409.12183, ICLR 2025.

Examples work through their shape, not their answers. Min and colleagues found that randomly replacing the labels in demonstrations barely hurt performance across 12 models: what carries the benefit is the label space, the input distribution and the format. arXiv:2202.12837, EMNLP 2022.

A rigid output format can cost reasoning. Tam and colleagues report a decline in reasoning under format restrictions, with stricter constraints costing more. This is why the check asks for reasoning first and formatting second, rather than treating a schema as free. arXiv:2408.02442.

Asking a model to flag uncertainty is a preference, not a finding. The check rewards it because a stated instruction is cheap and a fabricated citation is expensive. No controlled result is cited for it because none was found.

People do paste sensitive data into these tools. LayerX reported that around 18% of enterprise employees paste data into generative AI tools, that more than half of those pastes include corporate information, and that roughly 72% of access happens through non-corporate accounts (Enterprise AI and SaaS Data Security Report 2025). Cisco's 2024 Data Privacy Benchmark Study, covering 2,600 privacy and security professionals across 12 countries, found 48% had entered non-public company information into such a tool.