Is my JSON uploaded to a server?

No. All formatting, validation, repair, querying and diffing run entirely in your browser. Your data is never uploaded unless you explicitly choose to.

JSON Diff — Compare Two JSON Files Online

Input (paste JSON — valid or broken)

Edit history — saved locally in this browser:

Compare current JSON (A) with B, then Run diff:

Output

Paste a JSON Schema, then Run validation:

JSONwiz — the free online JSON toolkit

JSONwiz is a fast, privacy-first workspace for reading, fixing, and transforming JSON right in your browser. Paste JSON into the panel above — valid or broken — and format it, validate it, repair it, explore it as a tree or table, query it with jq or JSONPath, convert it to other formats, and generate code from it. Everything runs locally on your device: your data is never uploaded to a server, and there is no sign-up required. The tools are built to handle large, multi-megabyte files that normally freeze other online editors.

What JSONwiz can do

Every button in the toolbar maps to a focused tool. Here is what each one does:

Format & Minify

Pretty-print messy JSON with clean indentation, or compress it to a single line to save space. Output is syntax-highlighted with line numbers.

Validate

Instantly check whether your JSON is valid. If it isn't, JSONwiz shows the exact error with the line and column and highlights the break point in the editor.

Repair broken JSON

One click fixes the most common problems: trailing commas, single quotes, unquoted keys, and missing brackets. It can recover the valid part of a truncated file and detect NDJSON (newline-delimited records), turning it into a proper array. Added characters are boxed so you can see exactly what changed.

Tree view

Explore deeply nested data as a collapsible tree — it works even when the JSON is invalid, and stays fast on very large documents.

Table view

Turn an array of objects into a sortable, Excel-style table, and export it as a Markdown table with one click.

jq & JSONPath query

Filter and reshape data with a live query bar using either jq (e.g. .users[] | select(.active)) or JSONPath (e.g. $.users[*].id).

Generate code

Convert a JSON sample into strongly-typed code: TypeScript interfaces, Go structs, Python classes, or Rust structs — plus JSON Schema.

Validate against a schema

Paste a JSON Schema and check your data against it, with clear messages for every field that fails.

Diff

Compare two JSON documents structurally and see exactly what was added, removed, or changed, by path.

Convert formats

Convert JSON to and from YAML, CSV, TOML, and XML.

Transform

Sort keys alphabetically, remove duplicate array items, or flatten and un-flatten nested objects into dot-notation.

Decode

Decode a JWT (showing its header and payload), Base64, or gzip payload into readable JSON.

Share link

Encode your document into a shareable URL — no account or server storage needed. Anyone who opens the link sees the same JSON.

History

Your edits are snapshotted automatically and saved locally, so you can roll back to an earlier version at any time.

Instructions: how to use JSONwiz

Paste your JSON into the input panel on the left. It can be valid or broken — the editor colours the syntax as you type either way.

Read the result on the right. If the JSON is valid it is pretty-printed automatically. If it isn't, a red banner shows the error and marks the exact spot; click jump to break to scroll straight to it.

Fix problems with the Repair button — it cleans up trailing commas, quotes, brackets, and more, or offers to keep the valid portion / parse newline-delimited records.

Switch views with the Formatted, Tree, and Table tabs to read the data the way that suits the task.

Query by typing a jq or JSONPath expression into the query bar above the output.

Do more from the toolbar: generate types, validate a schema, diff two documents, convert to YAML/CSV/TOML/XML, transform keys, decode a token, or create a share link.

Copy the result with the Copy button (in Table view it copies a Markdown table). Use the language selector to switch the interface between 27 languages.

Common tasks

Beautify JSON: paste it, then press Format.

Fix invalid JSON: paste it, then press Repair — the boxes in the editor show what changed.

Extract a field: type a query such as .items[].name in the query bar.

Turn JSON into TypeScript or Go: pick the language and press Generate.

Compare two files: press Diff, paste the second document, and run the diff.

Convert JSON to CSV: for an array of objects, choose CSV and press JSON →.

Privacy

JSONwiz processes your JSON entirely in your browser using local code and Web Workers. Your data is not sent to, stored on, or logged by any server. Nothing leaves your device unless you deliberately create a share link (which encodes the data in the URL you choose to share). There is no account and no tracking of your JSON content.

Frequently asked questions

Is JSONwiz free?

Yes. All tools are free to use, with no sign-up required.

Is my JSON uploaded anywhere?

No. Formatting, validation, repair, querying, and diffing all run locally in your browser.

Can it fix broken JSON?

Yes — the Repair tool fixes trailing commas, single quotes, unquoted keys, and missing brackets, recovers a valid prefix, and detects NDJSON.

How large a file can it handle?

It is designed for multi-megabyte files using virtualized rendering and background workers.

What is the difference between jq and JSONPath?

Both query JSON. jq is a powerful transformation language; JSONPath is a simpler path syntax like $.a.b[0]. JSONwiz supports both.

JSON Diff — Compare JSON