JSON to JSON Schema & LLM Structured Output Generator
Convert mock JSON to JSON Schema and compile adapters for OpenAI Strict Structured Outputs, Gemini responseSchema, and Anthropic Tools.
An advanced, privacy-first developer utility designed specifically for the AI agent and Large Language Model era. Easily paste any mock JSON payload, and our algorithm will recursively analyze the structure to infer types (objects, nested arrays, booleans, integers, floats, and nulls). It features smart format sniffing to auto-detect emails, UUIDs, dates, and URIs. Most importantly, it bridges the gap for AI developers by providing custom adapters for LLM APIs: it compiles strict OpenAI response_format parameters (recursively injecting additionalProperties: false and packing all keys into required arrays), formats schemas for Gemini responseSchema, and wraps structures into Anthropic's tools schema envelope, all with ready-to-copy Node.js and Python SDK snippets.
How to use
- 1
Input your JSON
Paste your sample JSON payload into the input editor, or click 'Load Sample' to populate a realistic nested object profile.
- 2
Configure Schema settings
Open Settings to choose the draft version, toggle smart format sniffing, force recursively required keys, or add template description notes.
- 3
Switch SDK integration tabs
Switch between standard JSON Schema, OpenAI response_format, Gemini responseSchema, or Anthropic Tools to see compiled code blocks.
- 4
Copy and paste into your code
Click the Copy button to immediately save the formatted block to your clipboard, or click Download to save the schema.
FAQ
Q.Why does OpenAI require strict schemas, and how does this tool help?
To guarantee 100% structured schema adherence, OpenAI requires that all properties must be listed in the 'required' array and 'additionalProperties' must be false on every nested object. Doing this by hand is extremely tedious. Our tool does this automatically and recursively when you select the 'OpenAI Strict JSON' tab.
Q.Does this tool upload my JSON data anywhere?
No. All inference, formatting, and SDK code generation run entirely client-side within your browser. No network requests are made, keeping your private business logic and mock schemas 100% secure.
Q.How does the 'Smart Format Sniffing' work?
Our parser runs regular expression checks against string values. If a string conforms to standard UUID, email, date-time, uri, or IPv4 structures, it automatically appends the corresponding 'format' keyword to the schema, matching industry validation standards.
Q.Can it handle complex arrays with mixed object structures?
Yes. Instead of just picking the first item, our algorithm merges all item schemas recursively. It gathers every unique key present across all array objects and merges their sub-types so that the final inferred array items schema represents a unified model of all elements.
Q.Which versions of JSON Schema drafts are supported?
We support Draft-07 (most popular for common validation), Draft 2020-12 (latest standard), and Draft-04 (highly compatible legacy version). You can dynamically switch versions in the Settings dropdown.