JSON to TypeScript
Generate TypeScript interfaces from JSON samples free, online, in your browser. No upload. Customize root type name, infer arrays, quote keys.
Runs locally in your browser. Your input is not uploaded to DevToolMate servers.
Inference limits
Object shapes become exported interfaces. Arrays use the first element to infer the item type.
Developer Quick Tips
- Set a custom root type name before conversion, default is 'Root'. Change it to match your API response class or interface name.
- Array inference uses the first element to determine item type. Add a sample item if arrays appear as unknown[].
- Non-identifier property keys (e.g., 'user-id', '123prop') are automatically quoted in generated TypeScript output.
- Paste JSON from API responses, logs, or config files. Download the generated types.ts or copy interfaces directly into your codebase.
- Pair with JSON Formatter to validate syntax before conversion, or JSONPath Query to extract nested payloads first.
Frequently asked questions
How do I generate TypeScript interfaces from JSON?
Paste or upload a JSON sample, set your root type name, and click Convert. JSON to TypeScript infers object shapes as exported interfaces and arrays as typed collections. Download types.ts or copy the output directly.
Can I customize the root type name?
Yes. Before running the conversion, enter your desired interface name in the 'Root Type Name' field. Default is 'Root'. This name is used for the top-level exported interface.
How does array inference work?
JSON to TypeScript uses the first element in an array to infer the item type. Empty arrays default to unknown[] until you provide a sample item. Nested arrays and objects are fully typed based on their structure.
What happens to property keys with special characters?
Non-identifier keys (spaces, hyphens, numbers at the start) are automatically quoted in the generated TypeScript. For example, 'user-id' becomes a quoted property in the interface.
Does JSON to TypeScript upload my data?
No. All processing happens locally in your browser. Your JSON input is never uploaded to DevToolMate servers. It stays on your device for the current session only.
Is JSON to TypeScript free?
Yes, completely free. No account, no login, no limits. Generate as many TypeScript interfaces as you need.
Related tools
- JSON Formatter: Online JSON formatter - beautify and format JSON in your browser with adjustable indentation and key sorting. Free, no upload, no account.
- JSONPath Query: Free jsonpath online tool to query JSON in your browser. Extract fields with dot notation, array indexes, and wildcards. No upload, no account, no server processing.