JSON to TypeScript Interface Generator

Example

[{"id":1,"name":"Ada"},{"id":2,"age":30}] becomes an interface with id: number, name?: string and age?: number.

Quick answers

Can I get a Zod schema instead?

Yes — switch the mode to JSON → Zod schema.

How to use JSON Converter

1. Choose what to convert to: TypeScript, Zod, CSV — or CSV to JSON.
2. Paste your JSON (or CSV). The output updates as you type.
3. Copy it or download it as a file.

What makes the types accurate

• Looks at every item in an array, not just the first: a field missing from some objects becomes optional (age?: number), and mixed values become unions (number | string).
• Handles null as | null in TypeScript and .nullable() in Zod.
• Names nested types from their keys — orders becomes Order, categories becomes Category.
• Zod output compiles as-is, with schemas declared before they're used and a matching z.infer type.

CSV details

• Nested objects become dotted columns (meta.score); every key across all rows gets a column.
• Cells starting with =, +, - or @ are escaped so spreadsheets don't run them as formulas.
• CSV → JSON detects comma, semicolon or tab delimiters, handles quoted values and line breaks, and keeps codes like 01234 as text.

Frequently asked questions

Is my JSON sent to a server?

No. Conversion happens in your browser; nothing you paste is uploaded or stored.

Which Zod version is the output for?

It uses the core API (z.object, z.array, z.union, .optional(), .nullable()) that works in Zod 3 and Zod 4.

My JSON has an error — what now?

Open it in the JSON Formatter, which explains the error and can repair common problems like trailing commas or single quotes.

What does an empty array become?

unknown[] in TypeScript and z.array(z.unknown()) in Zod, because there's nothing to infer from. Paste a sample with at least one item for a precise type.