Structured Output Builder
Define your fields once and generate the structured-output schema for OpenAI, Anthropic, Gemini, or plain JSON Schema. No more hand-writing each provider's flavor. Runs in your browser.
One schema, every provider
Structured outputs and tool calling both come down to one thing: a JSON Schema the model must conform to. But every provider wraps that schema differently. Define your fields once here and get the right shape for each:
- JSON Schema: the portable base (draft 2020-12),
additionalProperties: false. - OpenAI: a
response_formatof typejson_schemawithstrict: true. - Anthropic: a tool whose
input_schemais your schema (the model “calls” it with the data). - Gemini: a
responseSchema(uppercase OpenAPI types) plusresponseMimeType.
Tip for OpenAI strict mode: it expects every property to be listed as required. This builder
handles that for you, any field you leave unchecked is emitted as nullable (["type", "null"]) in the OpenAI tab,
which keeps the schema valid instead of dropping it from required.
Field types
string, number, integer, boolean, an enum (comma-separated values → a closed set),
and typed arrays. Add a description to each field, it steers the model far
more than the field name alone.
FAQ
Does a schema guarantee correct data?
It guarantees the shape, right fields and types. It can’t guarantee the model put the right value in a field; validate business rules yourself.
Is this the same as function calling?
A tool/function call’s arguments are a structured output, the same JSON Schema, wrapped as a tool. The Anthropic tab shows exactly that form.
Is anything uploaded?
No, schema generation runs in your browser, so your field names and structure stay local and it works offline.
Related
Read structured outputs and tool calling, or browse AI Explained.