zippydevtoolsJSON
JSON to TypeScript
Generate TypeScript interfaces and types from valid JSON samples in the browser.
Process the input to see the result here.
Generate TypeScript interfaces or types from a JSON sample to speed up API integration and frontend model work.
When to use
Use it when you have an example JSON response and want a starting TypeScript type without writing every field manually.
Input
Paste valid JSON and choose a root type name. Inference is based on the shape of the provided sample.
Output
The output is TypeScript code with interface or type definitions, including nested objects, arrays, and inferred optional fields.
- Paste a valid JSON sample that represents the API response.
- Set the root type name and choose interface or type output.
- Generate the code and review optional fields, arrays, and inferred names.
- Validate JSON first and adjust the generated type when the sample does not cover all real cases.
- API integration: Create starter types for REST responses, mocks, and frontend TypeScript models.
- Object arrays: Infer list item shapes and optional fields from arrays with missing keys.
- Technical documentation: Turn JSON examples into readable types for internal docs and SDK notes.
- Incomplete samples: Generated types reflect only the sample; missing real fields cannot be inferred.
- No runtime validation: TypeScript output does not replace runtime validation, schemas, or safe parsing.
- Normalized names: The root name becomes PascalCase and may receive a prefix when it starts with a number.
- Null values: Review null fields manually because real contracts can accept more types than the sample shows.
- JSON Formatting, Validation, and TypeScript Workflow
Move from unreadable JSON to validated payloads and TypeScript interfaces with a practical workflow for API responses and config files.
Infer a response type
Input: {"user":{"id":1,"name":"Ana"}}
Output: TypeScript interfaces or types based on the sample.
Does output exactly match my API contract?
Not always. Types are inferred from the JSON sample you provide.
Can I choose interface or type output?
Yes. You can generate either interface or type output style.
Is the root type name normalized?
Yes. It is normalized to PascalCase and gets a T prefix if it starts with a number.
Are optional fields inferred automatically?
Yes. Missing keys across array object samples can become optional properties.
Does it validate JSON Schema?
No. It performs type inference from sample data, not formal schema validation.
How do I use this tool safely?
Use the tool as a short workflow: review the expected input, run processing, and validate the output: Fields: JSON sample (textarea, required); Root type name (text, required); Output format (select, required). Example workflow: {"user":{"id":1,"name":"Ana"}} -> TypeScript interfaces or types based on the sample.. Enter the requested input, run the tool, and review validation messages or warnings before copying the result.
Which inputs and outputs should I check?
Check this tool's input fields, examples, and output before using the result: JSON sample (textarea, required); Root type name (text, required); Output format (select, required). Use the fields, formats, and limits described in the tool interface; review the output before applying it to critical workflows.