JSON Formatter & Validator

Format, validate, tree-view, schema-gen, type-gen, diff. 100% browser-side.

100% browser-side · your JSON never leaves this tab

JSON input

Free · No signup · 100% browser-side

The JSON Formatter every developer wishes the others were

Format, validate, explore, generate types, infer schemas, and diff documents, all in one tool, all in your browser. Your JSON never leaves the tab.

How it works

Step 1

Paste, drop, or type

Drop a .json file, paste from clipboard, or type. Up to 50 MB. Everything runs in your browser.

Step 2

Format, validate, explore

Pretty-print or minify, view as a live tree, hover any node to copy its JSONPath.

Step 3

Generate types or schema

One click to a TypeScript interface, Zod schema, Go struct, or full JSON Schema (draft-2020-12).

Every feature, free

Format + minify

Indent with 2 spaces, 4 spaces, or tabs. Minify to a single line for embedding. Round-trip safe, so your input is never lossy-modified.

Pinpoint errors

Errors point to the exact line and column. Common JS-vs-JSON mistakes (single quotes, trailing commas, comments, unquoted keys) get one-click auto-fix.

Tree explorer + JSONPath

Navigate huge documents. Hover any node and click to copy a JSONPath like $.users[0].address.zip. No competitor on page-1 of Google has this.

JSON Schema generator

Auto-derive a draft-2020-12 JSON Schema from any sample. Detects formats (date, email, URL, UUID), required fields, array element types. Ready for AJV, OpenAPI, or contract tests.

Type generator

TypeScript interface, Zod schema, or Go struct from any JSON sample. Use it to type API responses, generate boilerplate, or document a contract.

Diff two documents

Side-by-side compare with added / removed / changed paths. Order-independent for objects, position-aware for arrays. Perfect for API regression testing.

Live metrics

Size, max nesting depth, and total node count update as you type. Catch ballooning payloads before you ship them.

100% browser-side

JSON.parse runs locally. Your data is never uploaded, never logged, never seen by us. The page works offline after first load.

Why we built this

Privacy that's actually private

Most free formatters ship your JSON to a server for processing. Some ad-supported sites log your inputs. We do not. The whole tool is a browser bundle. Close the tab and the data is gone.

No daily caps

Unlimited use. No signup. No watermark. JSONLint shows ads, JSONFormatter has size limits, JSONFormatter.curiousconcept.com makes you sit through interstitials. We don't.

Tools nobody else bundles

Tree explorer with click-to-copy JSONPath, JSON-Schema generator, and TypeScript/Zod/Go converter, all in one tool. Most competitors do one or two and ad-gate the rest.

Built for real-world JSON

Handles the JS-vs-JSON gotchas that frustrate users: trailing commas, single-quoted strings, unquoted keys, comments, undefined values. Auto-fix in one click, no manual hunt.

Molixa vs JSONFormatter, JSONLint

Feature	Molixa JSON Formatter	JSONFormatter.org	JSONLint
Free tier	Unlimited, no signup	Ad-supported, capped	Ad-supported
Privacy	100% browser-side	Server-processed	Server-processed
Tree explorer	Yes, click-to-copy JSONPath	Static collapse only	No tree
JSON Schema generator	Yes, draft-2020-12	Paid tier	No
TypeScript / Zod / Go types	Yes, all three	No	No
Diff two documents	Yes, built in	Separate tool	No
Auto-fix JS-isms	Yes, one click	No	No (errors only)
File size limit	50 MB	5 MB free	1 MB
Works offline	Yes, after first load	No	No

What developers use it for

Debug an API response

Paste the response, instantly spot the structure, copy a JSONPath to file in your bug ticket.

Type an API contract

Drop a sample response from the backend, get a TypeScript interface or Zod schema, paste into your client code.

Document a config file

Run the schema generator to produce a JSON Schema. Commit it next to the config so editors validate as you type.

Diff a regression

Paste yesterday's API response and today's. The diff tool shows exactly what changed and where.

Sanity-check a webhook

Paste the raw body. Catch malformed payloads before they crash your handler. Fix common JS-isms with one click.

Onboard a new endpoint

Run the type generator + schema generator together. Get types, validation, and documentation in 30 seconds.

Walkthroughs

From sample JSON to a typed Zod schema in 10 seconds

1Paste your sample JSON (e.g. an API response).
2Click the Types tab.
3Switch the dropdown to Zod.
4Click Copy. Paste into your TypeScript codebase. You now have a runtime-validated, type-inferred schema.

Generate a JSON Schema for an OpenAPI spec

1Paste a sample of one endpoint's response shape.
2Click the Schema tab.
3Copy the result and paste under `components.schemas.<Name>` in your OpenAPI YAML.
4AJV, Swagger UI, and most OpenAPI tooling consume draft-2020-12 directly.

Find what changed between two API responses

1Paste yesterday's response in the main input.
2Click the Diff tab and paste today's response in the comparison field.
3The diff lists added paths in green, removed in red, and changed in amber, with the exact JSONPath for each.

Auto-fix JSON copied from a JS console

1Paste the JS object literal (single quotes, trailing commas, all of it).
2The error banner lists every JS-ism it found.
3Click Apply all fixes. The input becomes valid JSON in one shot.

Privacy + security

Your JSON never leaves your browser

The entire tool runs as a single browser bundle. JSON.parse, the formatter, the validator, the tree explorer, the schema generator, and the type converter all execute locally. There is no API call, no server upload, no log of your input. Close the tab and your data is gone.

That matters when you're pasting payloads with API keys, customer records, internal IDs, or anything else you don't want a third party to see. It also means the tool works offline once the page has loaded, which is handy for airplanes, locked-down corporate networks, or air-gapped environments.

Who it's built for

Backend developers

Debug API payloads, generate types from sample responses, validate config files.

Frontend developers

Type API responses with Zod or TypeScript, navigate deeply nested data, copy JSONPath for tests.

DevOps + SRE

Diff config drift, validate webhook payloads, generate JSON Schema for contract tests.

QA + integrations

Reproduce API regressions with the diff tool, document exact paths in bug reports, validate response shapes.

Questions developers ask

Is the JSON formatter free?

Yes. Unlimited use, no signup, no daily cap, no watermark, no upload size limit. JSON runs entirely in your browser, so there is no API call and the tool is genuinely free for us to host. JSONFormatter.org and JSONLint show ads and have load-time data limits; we don't.

Is my JSON data private?

Yes. Everything runs in your browser. Your JSON is never sent to our servers, never stored, never logged. Close the tab and the data is gone. This is the biggest difference between us and many free formatters that ship JSON to a remote service for processing.

How big a file can I format?

Up to 50 MB in modern browsers. The interactive tree explorer is virtualized, so even 100k-key documents render at 60fps. Beyond 50 MB, the browser may hit memory limits, and at that size you usually want a CLI tool like jq instead.

What does the validator catch?

Strict RFC-8259 violations: missing commas, unbalanced braces or brackets, trailing commas (allowed in JS but invalid in JSON), unescaped control characters, malformed Unicode escapes, single-quoted strings (only double quotes are valid in JSON), and number format errors. Errors point to the exact line and column.

Can I generate TypeScript types from a JSON sample?

Yes. Paste any JSON, click Type Generator, and you get a TypeScript interface (with optional fields detected from null/undefined values), a Zod schema, or a Go struct. Useful for typing API responses or generating boilerplate from a sample document.

Can I generate a JSON Schema from a sample?

Yes. The Schema Generator produces a draft-2020-12 JSON Schema by inferring types, required fields, and array element types from the structure you give it. The output is ready to paste into AJV, OpenAPI specs, or contract tests.

What is the tree explorer good for?

It lets you navigate huge documents without scrolling raw text. Click any node to expand or collapse. Hover any value and click the path icon to copy a JSONPath like $.users[0].address.zip. Useful when filing bug reports, writing JSONPath queries, or jq filters.

Can I diff two JSON files?

Yes. The Compare tab shows added, removed, and changed paths between two documents side by side. Order-independent for objects, position-aware for arrays. Good for debugging API response changes or config drift.

Why is JSON.parse stricter than what I am used to?

JavaScript object literals are not the same as JSON. JSON requires double-quoted keys, double-quoted strings, no trailing commas, no comments, no functions, and no undefined values. The validator highlights every difference between a JS literal and valid JSON, with a one-click fix for the common ones.

Does it work offline?

Yes after the first page load. The tool is a pure browser app and the bundle is cached by your browser. You can format, validate, generate types, and view trees with no internet connection. The only thing offline-mode disables is sharing via short link.

Try it now

Format any JSON in seconds, your data stays private

No signup, no daily cap, no watermark. Drop in a 50 MB file or paste from your console. Generate types, schemas, and diffs without leaving the page.

Start formatting

Built and reviewed bySaqib Zahoor, WeboTech Studio

Last updated: May 14, 2026

The JSON Formatter & Validator page is built, reviewed, and maintained by the Molixa team. We use the tool we ship and update the docs when the behavior changes.

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