Free · no signup · browser-local
Function Calling Schema Builder: Responses, Chat and Anthropic
Create an API-specific tool object from a supported inline JSON Schema. Inspect OpenAI strict-mode constraints and download actual tool definitions locally.
Browser-local preparation and checks · no model calls · no input storage
Your output
result.jsonComplete the input to preview and export your result.
These are local preparation and validation tools. A passing check is limited to the stated rules; services are not called, authenticated or executed.
Getting started
Choose an API format, name, description and supported inline schema. OpenAI strict mode requires every object to be closed and all properties required.
Before you use the result
A conservative inline schema subset is checked locally. No API request runs; model compatibility and advanced schema features must be checked in the target platform.
Try an example
Load the built-in example, change one value and inspect the actual exported result.
How it works
Bounded browser-local parsing and deterministic rules; no model calls, arbitrary code or remote schema fetches.
Frequently asked questions
Wrap an inline JSON Schema for OpenAI Responses, Chat Completions or Anthropic tools.
How do I use Function Calling Tool Schema Builder?
Choose an API format, name, description and supported inline schema. OpenAI strict mode requires every object to be closed and all properties required.
Does this tool upload my data?
Inputs and files are processed in your browser. Page-view analytics do not contain your tool input.
What should I check before using the result?
A conservative inline schema subset is checked locally. No API request runs; model compatibility and advanced schema features must be checked in the target platform.