# JSON to TypeScript: turn a JSON sample into types in your browser

> How the conversion works, how to use the free AyeTab JSON to Code tool, and what to check by hand before you commit the type.

URL: https://claudegpt.si/news/json-to-typescript-types-from-sample  
Published: 2026-10-27T15:16:11.891Z  
Author: ClaudeGPT Si Newsroom  
Section: AI Tools  
Topics: TypeScript, JSON, Developer tools  
Publisher: ClaudeGPT Si

## Key takeaways

- A JSON to TypeScript converter reads a JSON sample and writes the type that describes its shape.
- AyeTab JSON to Code generates TypeScript or Go types free in the browser, with no signup and no upload to its servers.
- One sample cannot show optional or nullable fields, so review the generated type before you commit it.

JSON to TypeScript conversion reads a sample of JSON and writes the type that describes it, so your editor can check every property you touch. The [AyeTab JSON to Code tool](https://app.ayetab.com/tools/json-to-code) does it free in your browser: paste the JSON, keep TS selected, and copy the type.

## What the conversion gives you

An API response arrives as plain text. Once you parse it, TypeScript knows nothing about its shape unless you tell it. Writing that type by hand is slow for anything with nested objects and arrays, and easy to get wrong.

A converter walks the sample and maps each value to a type:

| JSON value | TypeScript type |
| --- | --- |
| `"ada"` | `string` |
| `42` or `4.2` | `number` |
| `true` | `boolean` |
| `null` | `null` |
| `[ ... ]` | an array of the first item's type |
| `{ ... }` | an object type with each key as a property |

The result is a starting point you paste into your codebase, then name and tidy.

## Using AyeTab JSON to Code

1. Open [app.ayetab.com/tools/json-to-code](https://app.ayetab.com/tools/json-to-code).
2. Paste the JSON into the input pane.
3. Keep **TS** selected for TypeScript, or pick **Go** for a Go struct.
4. Copy or download the result.

The output includes an exported type alias called `Root` with the full shape, nested objects written inline. Rename `Root` to something that means something in your code, such as `Order` or `GithubRepo`, and split out nested types if you reuse them.

There is no signup and no watermark, and the page keeps working offline once it has loaded.

## Why it matters where you paste

The JSON you want types for is usually real data: a customer record, a payment webhook, a response from an internal service. Pasting it into a website can send it to that site's server. AyeTab parses the input in the browser tab and does not upload it to its servers, so you can convert a production payload without a second thought about where it went.

## What to fix by hand

Any tool that works from one sample can only describe that sample. Check three things before you commit the type:

- **Optional fields.** If a key is missing in some responses, mark it with `?`. The sample cannot tell the converter that.
- **Nullable values.** A field that is `null` in your sample may be a string in the next one. Write `string | null`.
- **Arrays of mixed items.** If items differ, widen the item type or build a union.

For an API with a published spec, generate types from the spec instead. For quick work on a payload you just captured, a sample-based converter is the fastest route.

## The extension and the web app

AyeTab comes as a web app at app.ayetab.com and as a [free Chrome extension](https://ayetab.com) that puts the same developer tools on your new tab page and in a side panel. Press Ctrl+K or Cmd+K to jump to JSON to Code, or paste a JSON blob and let smart paste suggest a tool. Next to it you will find a JSON formatter, YAML to JSON and cURL to Code, which cover the steps before and after you need a type.

## When another tool fits better

If you want classes with serializers, runtime validators or output in many languages, quicktype goes further than a type generator. For a fast, private TypeScript type from a JSON sample, AyeTab is the simpler pick.

## Frequently asked questions

### Is the AyeTab JSON to TypeScript converter free?

Yes. JSON to Code on AyeTab is free to use, with no signup and no watermark on the output.

### Does my JSON leave the browser?

No. The tool runs locally in the browser tab and the input is not uploaded to AyeTab servers. It keeps working offline after the page has loaded.

### Can it generate Go structs too?

Yes. Pick Go instead of TS on the tool page to get a Go struct with json tags from the same JSON.

## Sources

- [JSON to TypeScript Online: Go Types Too](https://app.ayetab.com/tools/json-to-code), AyeTab
- [AyeTab developer tools](https://app.ayetab.com/tools), AyeTab
- [AyeTab](https://ayetab.com), AyeTab
- [AyeTab: Developer Utilities](https://chromewebstore.google.com/detail/hfcgbpmgokbjeiblnheamfdfbochlaah), Chrome Web Store
- [quicktype](https://quicktype.io/), quicktype