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Format, validate, and minify JSON — right in your browser. No upload, no signup, no limits.
Check if your JSON conforms to a JSON Schema (Draft 7 / 2019-09 subset: type, required, properties, pattern, minimum, maximum).
Extract specific values from your JSON using JSONPath expressions. Supports basic path traversal and wildcard (*) matching.
Benchmarked against native JavaScript JSON.parse/JSON.stringify on real hardware. Our Rust/WASM core delivers consistent performance across input sizes:
| Size | Operation | Native (ms) | WASM (ms) | Ratio |
|---|---|---|---|---|
| 10 KB | Format | 0.126 | 0.749 | 5.94x |
| 10 KB | Validate | 0.058 | 0.133 | 2.29x |
| 10 KB | Minify | 0.107 | 0.211 | 1.97x |
| 50 KB | Format | 0.653 | 1.440 | 2.21x |
| 50 KB | Validate | 0.299 | 0.645 | 2.16x |
| 50 KB | Minify | 0.553 | 1.015 | 1.84x |
| 200 KB | Format | 3.370 | 6.187 | 1.84x |
| 200 KB | Validate | 1.227 | 2.652 | 2.16x |
| 200 KB | Minify | 2.402 | 4.308 | 1.79x |
* Benchmark results from bench/results.txt — measured on test hardware, actual performance varies by device.
Even experienced developers run into JSON syntax errors. Here are the most frequent issues and how to resolve them quickly.
{"name": "value",} is invalid. The trailing comma after the last property causes a parse error. Remove it and your JSON will be accepted.'name' uses single quotes, which are not valid in standard JSON. Always use double quotes: "name".{name: "value"} omits the quotes around the key. JSON requires all keys to be double-quoted strings: {"name": "value"}.{"a": 1 "b": 2} lacks a comma between entries. Add the comma: {"a": 1, "b": 2}.Our validator detects all of these and reports the exact line and column where the error occurs, so you can fix them in seconds rather than searching through large files by hand.
See how JSON formatting works with common real-world data structures. These examples cover API responses, config files, and deeply nested objects that developers encounter daily.
GitHub API responses are nested objects with arrays of resources. Formatting them makes it easy to find specific fields like user avatars, repository names, or issue states without squinting at a minified blob.
{\n "login": "octocat",\n "id": 1,\n "node_id": "MDQ6VXNlcjE=",\n "avatar_url": "https://github.com/images/error/octocat_happy.gif",\n "gravatar_id": "",\n "url": "https://api.github.com/users/octocat",\n "html_url": "https://github.com/octocat",\n "name": "mona octocat",\n "company": "GitHub",\n "location": "San Francisco",\n "email": "octocat@github.com",\n "hireable": false,\n "bio": "There once was...",\n "twitter_username": "monaoctocat",\n "public_repos": 2,\n "public_gists": 1,\n "followers": 20,\n "following": 0,\n "created_at": "2008-01-14T04:33:35Z",\n "updated_at": "2008-01-14T04:33:35Z"\n}
Stripe webhook events follow a similar pattern with a top-level data object containing the relevant payload. Formatting reveals the event type and object structure at a glance, which is critical when debugging payment flows.
Docker Compose files often include nested objects for service configuration, networks, and volumes. Validating the JSON before running docker compose up prevents cryptic errors that take minutes to diagnose.
{\n "version": "3.8",\n "services": {\n "web": {\n "build": ".",\n "ports": ["8080:80"],\n "environment": {\n "NODE_ENV": "production"\n },\n "volumes": ["./data:/app/data"]\n }\n },\n "networks": {\n "app-network": {\n "driver": "bridge"\n }\n }\n}
.env files are not JSON, but many tools export environment configs as JSON for documentation. Formatting these reveals which values are missing or incorrectly structured before you deploy.
Deeply nested JSON appears in GraphQL responses, Kubernetes manifests, and configuration management systems. A typical Kubernetes Pod spec can have 5-8 levels of nesting with objects inside arrays inside objects.
The key to managing nested JSON is consistent indentation and understanding the hierarchy. Use 2-space indentation for readability — 4 spaces make deeply nested files unwieldy, while 1 space makes structure hard to scan. Our formatter defaults to 2 spaces for this reason.
When working with arrays of objects (like GitHub search results), formatting makes it easy to see where one item ends and another begins. Look for matching bracket pairs to verify structure integrity at a glance.
Most online JSON tools upload your data to a server. Our formatter runs 100% in your browser — your JSON never leaves your machine. This matters when you're working with API keys, database configs, or any sensitive data. No account, no tracking, no rate limits. After the first load, it even works offline thanks to the service worker. Formatting and validation run in a bundled Rust/WASM core; native JavaScript is the fallback.
package.json, tsconfig.json, or any JSON config before committing. Catch errors before they break your build.JSON.parse() logic runs in your browser as in Node.js. A simple node -e "JSON.parse(require('fs').readFileSync('config.json'))" gives you the same validation in your pipeline.kubectl apply — a malformed ConfigMap can take down a deployment.curl -s https://api.example.com/data and paste the output, or use the browser DevTools network tab to copy the response body.json5 npm package or VS Code's built-in JSONC support can convert these formats before pasting into our validator.echo '{"key":"value"}' | json-formatter-validator — or more practically, use the command line: cat config.json | node -e "let d='';process.stdin.on('data',c=>d+=c);process.stdin.on('end',()=>JSON.parse(d))" for CI/CD validation.