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Structured Output Schema Builder

Turn a plain-language field list into a JSON Schema, a prompt fragment, real validation code, a repair prompt for drift, and edge-case test inputs — plus a warning when the shape itself is the reliability risk.

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  • Ships more than a schema: real validation code in your language, a repair prompt for when output drifts, and edge-case test inputs for missing, ambiguous, and out-of-range data.
  • The generated JSON is checked for real, client-side, the moment it's generated — never a self-reported "this is valid" from the model.
  • Actively checks the shape itself for reliability risk — an over-nested or over-constrained schema fails more often no matter how good the prompt is — and suggests a flatter alternative when that's the real problem.
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Frequently asked questions

This tool is powered by Claude (Anthropic).

A model asked to fill in deeply nested objects or satisfy many required fields at once fails more often, no matter how well the prompt is written — the failure mode is structural, not a wording problem. This tool checks for that and suggests a flatter shape when it would meaningfully improve reliability.

Real model output sometimes drifts from the schema — a missing field, a wrong type, an out-of-range value. The repair prompt is a ready-to-use re-prompt template that sends the invalid output and the specific validation errors back to the model and asks it to fix only what failed, rather than regenerating from scratch.

No. Answer the questions, get your schema and code, and download or copy them. An email address is required to generate the file and enforce a fair-use daily limit; no account is created.