free_tool
JSON to TypeScript & Zod
Paste a JSON response, get TypeScript interfaces and a matching Zod schema you can drop straight into your codebase. Nested objects become named types, arrays of objects merge into one shape with optional fields, and mixed types become unions. It runs entirely in your browser, so nothing you paste leaves the page.
export interface Profile {
city: string;
verifiedAt: null;
}
export interface Post {
id: number;
title: string;
pinned?: boolean;
}
export interface Root {
id: number;
name: string;
active: boolean;
roles: string[];
profile: Profile;
posts: Post[];
}Turning a sprawling API response into types by hand? I build typed, validated API layers so bad data fails at the edge, not three functions deep.
Type your API end to end: book a callInference is structural: it describes the sample you give it. A field that is null in the sample types as null, and a key missing from some array elements becomes optional, so feed it a representative payload (ideally a few records) for the best result. Generated Zod imports from "zod".
why_both
Types describe; Zod enforces
A TypeScript interface is a promise the compiler trusts. At runtime that promise is worthless: the API can send a string where you typed a number, and TypeScript never finds out. Zod closes the gap by validating the actual payload, so bad data fails loudly at the boundary instead of corrupting state three functions deep.
Generating both from the same sample keeps them in lockstep. Parse with the Zod schema at the edge (the fetch, the webhook, the form), and infer the TypeScript type from it with z.infer so you never write the shape twice.
faq
Questions & answers
- How does the JSON to TypeScript and Zod tool infer types?
- It reads the structure of your sample: nested objects become named interfaces, arrays of objects are merged into one shape, and a value that appears as more than one type becomes a union like string or number. It then emits matching TypeScript interfaces and a Zod schema.
- Does my JSON get sent anywhere?
- No. The whole conversion runs in your browser with no server call and no Zod dependency at runtime, so the JSON you paste and the code it generates never leave the page. That makes it safe for payloads from internal or private APIs.
- Why is a field marked optional when I know it is always present?
- When you paste an array of objects, the tool checks every element, and if a key is missing from even one of them it marks that field optional. Feed it a representative sample where every record has the field to keep it required.
- Is the generated schema the full contract for my API?
- No. Inference is purely structural and describes only the sample you give it, not fields or shapes the API can return but your sample happens to miss. Paste a few representative records for the most accurate result.
- Can I rename the top-level type?
- Yes. There is a root type name field that sets the name of the outermost interface and schema, and it is sanitized to a valid identifier, defaulting to Root.
Want your data typed and validated end to end?
I build typed API layers with validation at the boundary, so a bad response fails fast and visibly instead of leaking through your app. Book a call, or leave your email.
Prefer proof first? See how this plays out in real case studies →