01
Paste valid JSON
Use representative values from the API response or configuration you are reviewing.
Developer Tools
JSON to TypeScript Generator
Generate a reviewable TypeScript type from valid JSON locally, preserving mixed array values as visible union types.
0 / 200,000 characters
unknown[]; mixed arrays become visible union types. It does not guess optional fields, dates, enums, or application-specific models.Data handling
Storage and export controls
- Retention
- The tool's working state is kept only while this page is open. Inputs and results are not saved to persistent storage by Got A Tool.
- Export
- The tool may prepare a result after you run it. It downloads or copies it only when you choose that action.
Advertising and analytics are separate site services. We do not send selected tool input to them. Read the Privacy Policy for details.
How it works
Create a starting TypeScript type from real JSON values
02
Name the root type
Choose the exported type name you want in your codebase.
03
Review unions
Check mixed arrays, empty arrays, and quoted property names before copying the result.
Clear limit
Values are evidence, not a full schema.
A single JSON sample cannot prove every field that an API may return. This tool only maps the values present in the pasted sample. Add optional fields, stricter literal types, dates, and domain rules in your code after review.
Local processing
Pasted JSON stays in the current browser tab.
Mixed arrays
Different value types remain as explicit unions.
Empty arrays
No item type is invented for an empty array.
Safe property keys
Keys that need quoting stay quoted in output.
FAQ
Common questions
Does this create interfaces or a type alias?
It creates one exported type alias. Nested objects stay readable inline, which makes every inferred value visible in one result.
Why is an empty array unknown[]?
There is no item value to infer from. The tool shows that uncertainty instead of guessing a type.
Does this upload JSON?
No. Parsing and type generation happen only in your browser.
Keep working
Related tools
JSON Formatter & Validator
Format, minify, sort, and validate JSON locally with clear syntax feedback.
Open tool →JSON to YAML Converter
Convert valid JSON into explicit YAML locally, with text values quoted to preserve their meaning.
Open tool →JSON to XML Converter
Convert valid JSON into typed, indented XML locally without silently renaming invalid element keys.
Open tool →Regex Tester
Test a regular expression against sample text locally, with visible flags, matches, capture groups, and a time limit.
Open tool →