MapJSON Tools

Free, secure, and client-side JSON tools for developers. No data is ever sent to a server.

JSON Mapper

Rename, ignore, and restructure JSON fields securely in your browser. Perfect for API migrations.

JSON to YAML

Convert JSON objects to YAML format instantly. Ideal for K8s, Docker Compose, and config files.

JSON to ENV

Transform flat JSON objects into .env file format. Simplifying environment variable management.

JSON Formatter

Beautify, minify, and fix JSON formatting errors. Indent your JSON for better readability.

JSON Validator

Strictly validate JSON syntax against standards. Find and fix missing quotes or trailing commas.

JSON Diff

Compare two JSON files side-by-side. Highlight added, removed, and modified values.

JSON to TypeScript

Generate type-safe TypeScript interfaces from your JSON data automatically.

JSON Schema

Create JSON Schema (Draft 7) definitions from your JSON objects for validation.

JSON to CSV

Flatten JSON arrays into CSV format for easy export to Excel or Google Sheets.

JSON Viewer

Inspect complex JSON data with an interactive, collapsible tree view.

JSON Escape

Escape JSON strings for use in code or unescape them back to readable objects.

What is MapJSON Tools?

MapJSON Tools is a collection of free, professional-grade JSON utilities built for developers. Every tool runs entirely inside your browser: you paste or type your JSON, and all processing happens locally on your device. Nothing is uploaded to any server, and no copy of your data is stored by us. Whether you need to format, validate, compare, or transform JSON, you can do it quickly and safely from one place. The suite covers formatting, validation, comparison, conversion to YAML or CSV, type generation, schema creation, and more—all designed to work without accounts, installs, or data leaving your machine.

Why client-side JSON tools matter

Sending JSON to third-party servers can expose sensitive information such as API tokens, internal IDs, or confidential payloads. Client-side tools eliminate that risk: your data never leaves your machine. In addition, processing in the browser is fast—there is no network round-trip, so formatting, validation, and conversion feel instant. For teams working with production data or strict privacy requirements, client-side JSON tools are the safer and often faster choice. You avoid compliance and data-residency concerns because no copy is ever stored or transmitted to our infrastructure.

Tools included in this JSON toolkit

  • JSON Formatter — Beautify, minify, and fix indentation and formatting issues in your JSON.
  • JSON Validator — Check JSON syntax against the standard and catch missing quotes, trailing commas, and invalid structure.
  • JSON Diff — Compare two JSON documents side-by-side and see added, removed, and changed values clearly.
  • JSON Viewer — Explore complex JSON with an interactive, collapsible tree view.
  • JSON Mapper — Rename, ignore, or restructure fields for API migrations and data shaping.
  • JSON to YAML — Convert JSON to YAML for Kubernetes, Docker Compose, and config files.
  • JSON to ENV — Turn flat JSON objects into .env-style key-value format.
  • JSON to TypeScript — Generate TypeScript interfaces from sample JSON for type-safe code.
  • JSON Schema — Create JSON Schema (Draft 7) definitions from your JSON for validation.
  • JSON to CSV — Flatten JSON arrays to CSV for Excel, Google Sheets, or data pipelines.
  • JSON Escape — Escape or unescape JSON strings for safe use in code or config.

Who is this for?

MapJSON Tools is built for anyone who works with JSON: frontend and backend developers, DevOps engineers, QA testers, and data analysts. Use it to debug API responses, compare payloads before and after a change, generate TypeScript types from live data, migrate config from JSON to YAML or .env, validate webhook payloads, or inspect large JSON files without installing anything. All tools are free and run in the browser, so you can start immediately without sign-up or installation. Common use-cases include preparing API responses for documentation, diffing configs across environments, and converting JSON to formats required by other tools or teams.

Privacy & security

All processing is done in your browser. We do not send your JSON to our servers, and we do not store it. By default, nothing is persisted; refresh the page and the input is gone. As a best practice, we still recommend avoiding pasting highly sensitive secrets (e.g. production API keys) into any browser tab on a shared or public computer—but with MapJSON Tools, at least the data never leaves your device, which greatly reduces exposure compared to server-based tools. No logs of your input are retained, and there is no analytics on the content you paste.

FAQ

Is my JSON uploaded to a server?
No. Every tool runs entirely in your browser. Your JSON is never sent to our servers or any third party.
Is MapJSON Tools free?
Yes. All tools on MapJSON are free to use. There is no sign-up or subscription required.
Can I use it offline?
After you load the page once, the app can run offline in many cases because the logic runs in the browser. For full offline use, ensure the site is cached or saved for offline access.
What JSON size is supported?
Practical limits depend on your device and browser memory. Very large files (e.g. hundreds of MB) may slow down or exceed browser limits. For typical API payloads and configs, size is not an issue.
Does JSON Diff change my data?
No. JSON Diff only compares two inputs and shows differences. It does not modify, overwrite, or save your data anywhere.
How accurate is the JSON to TypeScript generator?
The generator infers types from the structure and sample values you provide. It is well-suited for drafts and quick iteration. For critical or complex schemas, we recommend reviewing and refining the generated types to match your API contract or documentation.

Try the JSON Formatter to clean up messy payloads, or use the JSON Diff and JSON Validator to compare and validate your data—all without leaving your browser.