How to Generate TypeScript Types From JSON
Updated 2026-06-21
To generate TypeScript types from JSON, paste a sample JSON object into a JSON-to-types generator, name the root type, choose TypeScript as the target language, and click Generate. The tool reads your example and infers an interface — field names, value types, nested objects, and arrays — that you can copy straight into your code.
Doing this by hand is slow and error-prone. Manually writing an interface for a deeply nested API response means tracking every key and guessing whether a field is a string, a number, or an object. A generator does the inference for you from a real payload, so the types match the data you actually receive.
Generate TypeScript Interfaces From a JSON Sample
Open JSON to TypeScript & Types and follow these steps:
- Paste a representative JSON object into the JSON input box. A worked example is pre-filled so you can see the format.
- Set the Top-level type name (it defaults to Root). This becomes the name of your root interface, struct, or class.
- Pick TypeScript from the language dropdown.
- Click Generate types. Your JSON is validated locally first, and any syntax error appears inline so you can fix it before anything is generated.
- Read the result in the output panel and use the Copy button to grab it.
The output is clean just-types mode — you get the interface declarations without extra serialization helpers or converter boilerplate, so there is nothing to delete before pasting.
Beyond TypeScript: Go, Rust, Python, Swift and More
The same JSON sample can produce types for eight languages. After generating, switch the language dropdown and regenerate to get the identical shape as:
- TypeScript interfaces
- Go structs
- Rust structs
- Python classes
- Java, C#, Kotlin, and Swift types
This is useful when a single API feeds clients in different stacks — generate once per language from the same payload and keep the shapes consistent. Under the hood it uses the quicktype engine, loaded on demand the first time you generate, so the page stays light until you need it.
Tips for Accurate Types
- Use a complete, representative sample. The generator infers types only from what it sees. If a field is sometimes missing or null in real data, include an example that reflects that so the inferred type isn't too narrow.
- Include populated arrays. An empty array gives the generator nothing to infer element types from. Provide at least one element so list items get a proper type.
- Name your root well. A meaningful top-level type name (for example, UserProfile instead of Root) produces cleaner, self-documenting nested type names.
- Fix invalid JSON first. Trailing commas and unquoted keys will trigger an inline parse error; the tool won't generate until the input is valid JSON.
Your JSON Stays Private
Because this runs entirely in your browser, your JSON is parsed and converted to types in the tab and never uploaded. That matters when your sample contains real API responses, tokens, or customer records — paste it without sending it to any server, and no account is required.
Ready to skip the hand-written interfaces? Generate your types now with JSON to TypeScript & Types.