Documentation
Complete guide to all JSONLab tools and features.
Getting Started
JSONLab is a free, browser-based developer toolkit for working with JSON data and JWT tokens. All processing happens entirely in your browser — nothing is sent to any server.
Key Features:
- 100% Client-Side: Your data never leaves your machine
- No Registration: No accounts, no sign-ups, no limits
- Free Forever: All tools are completely free to use
- Works Offline: Once loaded, most tools work without internet
- Dark & Light Mode: Switch themes for comfortable use day or night
Tools Reference
JSON Formatter / Validator
Beautify, minify, and validate JSON data.
How to use:
Paste your JSON input, choose Format (pretty-print with indentation), Minify (compress to single line), or Validate (check syntax).
Example:
{
"name": "JSONLab",
"version": "1.0.0"
}JSON ↔ YAML Converter
Convert between JSON and YAML formats.
How to use:
Select direction (JSON→YAML or YAML→JSON). Paste input in the source format and click Convert.
Example:
JSON: {"name": "test"} → YAML: name: testJSON ↔ XML Converter
Convert between JSON and XML formats. Handles nested structures and attributes.
How to use:
Select direction. Paste input and click Convert. Uses fast-xml-parser library.
JSON ↔ CSV Converter
Convert JSON arrays to CSV spreadsheets and back.
How to use:
For JSON→CSV, input must be a JSON array of objects. For CSV→JSON, paste CSV with headers.
Example:
[{"name": "Alice", "age": 30}, {"name": "Bob", "age": 25}]Base64 Encode/Decode
Encode text to Base64 or decode Base64 back to text.
How to use:
Select Encode or Decode. Toggle Base64URL mode for URL-safe encoding. Supports Unicode.
JSON Diff
Compare two JSON objects and see the differences highlighted.
How to use:
Paste the original JSON on the left and the modified JSON on the right. Click Compare.
JSONPath Query
Query JSON data using JSONPath expressions.
How to use:
Paste JSON data, enter a JSONPath expression, and click Execute Query. Try: $..price, $.store.book[*].title
JSON Escape/Unescape
Escape special characters in JSON strings or revert them.
How to use:
Select Escape to add backslashes, Unescape to remove them. Useful for embedding JSON in code.
JSON Schema Generator
Auto-generate JSON Schema (Draft-07) from your JSON data.
How to use:
Paste JSON data and click Generate Schema. The schema includes type definitions, required fields, and nested structures.
JSON → TypeScript Generator
Generate TypeScript interfaces from JSON data.
How to use:
Paste JSON, set a root interface name, and click Generate TypeScript. Creates nested interfaces automatically.
JSON Sorter
Sort JSON object keys alphabetically.
How to use:
Paste JSON and click Sort Keys. Toggle Reverse for descending order.
JWT Decoder
Decode JSON Web Tokens to inspect header and payload contents.
How to use:
Paste your JWT token on the home page and click Decode JWT. The header and payload are displayed as formatted JSON.
JWT Encoder
Create JWT tokens with custom header and payload.
How to use:
Select algorithm, set header fields, add payload key-value pairs or paste raw JSON. Click Generate JWT.
JWT Verifier
Decode and verify JWT token structure and signature.
How to use:
Paste the JWT token, optionally enter a secret key, and click Decode & Verify. Displays decoded content and validation status.
Supported JWT Algorithms
| Algorithm | Type | Description |
|---|---|---|
| HS256 | Symmetric | HMAC with SHA-256 |
| HS384 | Symmetric | HMAC with SHA-384 |
| HS512 | Symmetric | HMAC with SHA-512 |
| RS256 | Asymmetric | RSA with SHA-256 |
| RS384 | Asymmetric | RSA with SHA-384 |
| RS512 | Asymmetric | RSA with SHA-512 |
| ES256 | Asymmetric | ECDSA with P-256 |
| ES384 | Asymmetric | ECDSA with P-384 |
| ES512 | Asymmetric | ECDSA with P-521 |
| EdDSA | Asymmetric | Edwards-curve DSA |
| PS256 | Asymmetric | RSA-PSS with SHA-256 |
| PS384 | Asymmetric | RSA-PSS with SHA-384 |
| PS512 | Asymmetric | RSA-PSS with SHA-512 |
Technical Notes
Privacy & Security
All JSON and JWT processing happens entirely in your browser using client-side JavaScript. No data is transmitted to any server. This means you can safely process sensitive tokens and data.
JWT Verification
While JSONLab can decode and format JWT tokens, full cryptographic signature verification requires the secret key or public key. For production verification, use a proper JWT library like jose, jsonwebtoken (Node.js), or PyJWT (Python).
Browser Compatibility
JSONLab works on all modern browsers (Chrome, Firefox, Safari, Edge). Internet Explorer is not supported. For the best experience, use the latest version of Chrome or Firefox.