Free Online JSON Tools That Never Leave Your Browser
20+ free JSON tools that run in your browser: format, compare, convert, query, generate and encode.
JSON Formatter Hub is a free set of 20+ online JSON tools for formatting, validating, comparing, converting, querying and generating JSON. Every tool runs in your browser, so what you paste stays on your device and is never uploaded.
Your data stays in your browser
Every JSON Formatter Hub tool runs as JavaScript on your own device. What you paste is not uploaded to a server, not stored on a server, and not used to train AI. That makes the tools suitable for API responses and config files that contain names, emails or tokens, without worrying about where your data goes.
- Nothing uploaded
- No server storage
- Not used to train AI
- Works offline on desktop
- We never receive your content. There is no server step. The JSON you paste goes through code that runs in your own tab.
- Check it yourself. Open DevTools, go to the Network tab, and use any tool. You will see Google Analytics requests, which carry page and event details, and no request carrying what you paste or type. The only feature that makes a request on purpose is the homepage's Load from URL option, which fetches the address you enter.
- Works offline. After your first visit on desktop, the pages you have opened also load without a connection.
- Sensitive data. For live production secrets, use a private window on a trusted device, because browser extensions you have installed can read page content.
What we do collect: anonymous usage statistics through Google Analytics, such as page views and button clicks. It never includes anything you paste or type into a tool.
Read the full privacy policy, or see how client-side JSON formatting works and why it keeps your data on your device.
Most used JSON tools
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Beautify, validate and minify JSON, repair common mistakes with Auto Fix, and export the result to CSV, YAML or XML.
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See which keys were added, removed or changed between two JSON objects, shown side by side.
Format and validate JSON
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Explore JSON as a tree or a table, spot syntax errors with a line and column number, and minify it for production.
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Paste two documents and get a summary and a detailed difference report. Key order is ignored, while arrays are compared in order.
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Sort object keys alphabetically or sort an array of objects by a property, with every number kept exactly as you typed it.
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Check a document against a schema written for draft-07, 2019-09 or 2020-12 and read each failure as a plain error path.
Convert to and from JSON
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Turn CSV, TSV or semicolon-separated files into JSON, keeping zip codes as text and building nested keys from dotted headers.
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Convert XML to JSON and choose how attributes, arrays, namespaces and CDATA sections are mapped.
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Read YAML 1.2 or 1.1, including anchors, merge keys and multi-document files, and get JSON back.
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Open a spreadsheet in your browser and convert a chosen sheet to JSON, with options for sheets and dates.
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Turn a JSON array into JSON Lines, or JSONL back into an array, without changing how your numbers are written.
Query JSON
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Run JSONPath expressions against your JSON and see the matching values and their paths, with example filters to start from.
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Try JMESPath queries on your own JSON with live results, error messages that point at the problem, and 19 built-in examples.
Generate code, schemas and test data
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Infer a JSON Schema in draft 2020-12 or draft-07 from a sample payload in one step.
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Generate classes or types in six languages from a sample JSON document.
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Paste a cURL command from DevTools or Postman and get the matching fetch(), Python requests or Node axios code.
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Create realistic test data such as names, emails, IDs and addresses from a JSON Schema or a sample JSON.
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Create random version 4 UUIDs in bulk, with uppercase, no-hyphen and brace formatting options.
Encode and decode
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Read the header and payload of a JSON Web Token and see its expiry time in plain language.
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Sign a token with HS256, RS256, PS256 or ES256, or verify an existing one against your key.
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Encode or decode a URL or a query string instantly.
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Encode text to Base64 or decode it back, with UTF-8 and URL-safe options.
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Escape quotes, backslashes, newlines and Unicode inside a JSON string, or unescape a string back to plain text.
AI and LLM tools
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Count the tokens in your prompt text. Counts are exact for OpenAI models and estimates for the other model families.
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Convert JSON to TOON and back, then compare token counts on your own data to see whether the format helps.
Use it your way
The website
Open any tool in your browser on desktop or mobile. Start from the online JSON formatter or pick a tool from the lists above. There is no sign-up, and every tool is free to use.
The Chrome extension
The Chrome extension helps you inspect JSON while you browse. When you open an API endpoint or a raw JSON file, it gives you a readable tree view, search and formatting, with quick access to the full toolset. For Auto-fix, Remove Whitespace, Compare JSON or exports, use the website. The Chrome Web Store listing states that the developer will not collect or use your data.
Open the Chrome Web Store listing About the Chrome extension
Install as an app
On desktop Chrome and Edge, an Install app link appears in the footer of every page when your browser offers installation. Installing gives the tools their own window, and the pages you have already opened still load offline. The link is not shown on phones or tablets.
Frequently asked questions
Is my data uploaded?
No. Each tool is JavaScript that runs inside your own browser tab, so the JSON you paste is processed on your device and is never sent to our servers. The tools load their scripts from this site, and Google Analytics records anonymous page views and button clicks, but neither receives what you paste or type. The one feature that makes a request is the Load from URL option on the homepage, and it only fetches the address you enter.
Can I use it with sensitive data?
For most work, yes, because nothing you paste is uploaded or stored on a server. For live production secrets, use a private window on a trusted device, because browser extensions you have installed can read page content, and clear the editor when you are done.
Does it work offline?
After your first visit on desktop, the pages you have opened load without a connection and their tools keep working, because the site saves those pages in your browser. A page you have not opened yet needs a connection the first time. Phones and tablets do not use this offline copy.
Should I use the Chrome extension or the website?
Use the extension when you open raw JSON in Chrome, such as an API endpoint, and want a readable tree with search right there. Use the website when you need Auto-fix, Remove Whitespace, Compare JSON, exports to JSON, CSV, YAML or XML, or any of the converters and generators listed on this page.
How do I install it as an app?
On desktop Chrome or Edge, open any page of the site, click the Install app link in the footer and confirm the prompt. The app opens in its own window, and the pages you have visited still load offline. The link appears only when your browser offers installation, so you will not see it on phones or tablets.
Is it free?
Yes. Every tool on this page is free to use and needs no sign-up.