JSON to io-ts: a worked example

This is real output from the converter on this page, not an illustration. The input below deliberately includes the cases that trip up naive converters — a float, a null, an empty array, an array of mixed types, and a nested object.

Input JSON

{
  "id": 101,
  "name": "Ada Lovelace",
  "active": true,
  "score": 9.5,
  "deletedAt": null,
  "tags": [
    "admin",
    "ops"
  ],
  "scores": [],
  "mixed": [
    1,
    "two"
  ],
  "createdAt": "2026-01-15T08:00:00.000Z",
  "profile": {
    "city": "Lisbon",
    "zip": 1000
  },
  "addresses": [
    {
      "line1": "1 Rua Augusta",
      "country": "PT"
    }
  ]
}

Generated io-ts

import * as t from "io-ts";

export const User = t.type({
  id: t.number,
  name: t.string,
  active: t.boolean,
  score: t.number,
  deletedAt: t.union([t.null, t.null]),
  tags: t.array(t.string),
  scores: t.array(t.unknown),
  mixed: t.array(t.unknown),
  createdAt: t.string,
  profile: t.type({
  city: t.string,
  zip: t.number
}),
  addresses: t.array(t.type({
  line1: t.string,
  country: t.string
}))
});

How each JSON type maps to io-ts

Every row is generated by running that JSON value through the converter, so the table always matches what the tool actually emits.

JSON typeExample valueGenerated io-ts
string"Ada Lovelace"field: t.string
integer101field: t.number
float9.5field: t.number
booleantruefield: t.boolean
nullnullfield: t.union([t.null, t.null])
array of strings["admin", "ops"]field: t.array(t.string)
empty array[]field: t.array(t.unknown)
mixed-type array[1, "two"]field: t.array(t.unknown)
nested object{ "city": "Lisbon" }see the full example above
date-like string"2026-01-15T08:00:00.000Z"field: t.string

JSON to io-ts Converter – Free Online Tool

Convert JSON to io-ts instantly with JSONStudio's free online converter. Whether you're a backend developer working with configuration files, a DevOps engineer managing infrastructure as code, or a data analyst processing API responses, ourio-ts converter provides instant, accurate conversions with zero data uploads.

JSONStudio's JSON to io-ts converter runs entirely in your browser, ensuring maximum security and privacy. All processing happens client-side, so your sensitive JSON data never leaves your device. No signup, no tracking, no storage—just fast, reliable conversion when you need it.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data interchange format that's become the de facto standard for API communication, configuration files, and structured data storage. Its human-readable syntax and language-agnostic design make it ideal for modern web development, mobile apps, and microservices architectures.

JSON is used everywhere—from REST APIs and GraphQL responses to configuration files and database exports. Its simplicity and widespread support across programming languages have made it the preferred format for data exchange in modern software development.

What is io-ts?

io-ts is a powerful format used in modern software development for data representation, type definitions, and schema validation. Converting JSON toio-ts enables developers to work with structured data in formats optimized for specific use cases and programming languages.

JSONStudio's JSON to io-ts converter provides instant, accurate conversion from JSON to io-ts format, making it easy to integrate JSON data intoio-ts-based workflows and applications.

io-ts is a popular data format used in modern software development. Converting JSON to io-ts allows you to easily work with this format in your applications and tools.

Why Convert JSON to io-ts?

  • Compatibility: Convert JSON data to io-ts for use with specific tools
  • Data exchange: Share data in the format required by your team or project
  • Legacy support: Integrate with systems that require specific data formats
  • Readability: View your data in a different structure or layout

How to Convert JSON to io-ts Online

  1. Paste your JSON: Copy your JSON data from any source—API response, configuration file, or database export—and paste it into the left panel.
  2. Automatic validation: JSONStudio instantly validates your JSON syntax and highlights any errors, ensuring your data is properly formatted before conversion.
  3. Instant conversion: Select "io-ts" from the converter dropdown and watch as your JSON transforms into io-ts format in real-time.
  4. Copy or download: Use the one-click copy button to copy the converted io-ts output, or download it directly to your device.

All conversion happens entirely in your browser using client-side processing. Your JSON data is never uploaded to any server, ensuring complete privacy and security for sensitive information.

Features of JSONStudio JSON to io-ts Converter

  • Instant conversion: Real-time conversion with no delays or waiting
  • Large file support: Handle JSON files of any size without performance issues
  • Syntax highlighting: Color-coded output makes it easy to read and verify
  • Error detection: Automatic validation catches JSON syntax errors before conversion
  • One-click copy: Copy converted output to clipboard instantly
  • No signup required: Start converting immediately without creating an account
  • Free forever: All features available at no cost, with no usage limits
  • Dark mode support: Comfortable viewing in any lighting condition

Example JSON to io-ts Conversion

Input JSON:

{
  "name": "John Doe",
  "age": 30,
  "email": "john@example.com",
  "active": true
}

Converted io-ts:

// Converted io-ts output will appear here

Is JSONStudio Secure?

100% client-side processing: All JSON conversion happens entirely in your browser using JavaScript. Your data never leaves your device, ensuring complete privacy and security.

No logging or tracking: JSONStudio doesn't log, store, or track any of your JSON data. We don't use analytics that capture your content, and we don't maintain any server-side storage of your files.

No data uploads: Unlike many online converters that upload your files to servers, JSONStudio processes everything locally. This means even if you're working with sensitive API keys, passwords, or proprietary data, it remains completely private.

No server involvement: JSONStudio is a fully static site with no backend server. There is no server to send your data to, even accidentally.

Who Should Use This Tool?

  • Developers working with specific data formats
  • Data analysts processing JSON data
  • Students learning about different data interchange formats

Frequently Asked Questions

Is this JSON to io-ts converter free?

Yes, JSONStudio's JSON to io-ts converter is completely free with no signup required. All features are available at no cost.

Can I convert large JSON files to io-ts?

Yes, JSONStudio can handle JSON files of any size. All processing happens in your browser with no server-side limits.

Is my data safe?

Absolutely. All conversion happens entirely in your browser. We don't store or track any of your data.

Does it preserve JSON structure in io-ts?

Yes, the converter maintains the exact structure of your JSON data, converting it to equivalent io-ts syntax while preserving all data types and relationships.

Related Tools

JSONStudio offers a complete suite of JSON tools to help you work with JSON data more effectively: