JSON Toolkit

About

JSON Toolkit — Format, Compare, Decode & Convert. 100% Offline.

The all-in-one JSON utility that lives right in your browser toolbar. No servers, no accounts, no telemetry — everything runs locally on your machine.

━━ FEATURES ━━

🔧 FORMAT & VALIDATE
• Instantly pretty-print or minify any JSON
• Real-time syntax validation with clear error messages
• Auto-repair common JSON mistakes: trailing commas, single quotes, unquoted keys, JS-style comments
• Sort keys alphabetically for consistent diffs
• Choose your indentation: 2 spaces, 4 spaces, or tabs
• Syntax highlighting for easy reading
• Input history — revisit your recent snippets

🔍 COMPARE
• Side-by-side JSON diff viewer
• Highlights added, removed, and changed values
• Perfect for API response debugging and config audits

🔑 JWT DECODER
• Paste any JWT and instantly decode the header and payload
• Verifies structure and displays expiry, issuer, and all claims
• Works with any JWT — no secret needed to decode

🔄 CONVERT
• JSON ↔ YAML
• JSON ↔ CSV
• Instant conversion with formatted output

🌙 DARK MODE
• Comfortable light and dark themes, saved across sessions

━━ PRIVACY FIRST ━━

JSON Toolkit is 100% offline. Your data never leaves your browser — no network requests, no analytics, no external scripts. It works even without an internet connection.

No permissions required. No host access. No cookies.

━━ PERFECT FOR ━━

• Backend & frontend developers debugging API responses
• DevOps engineers inspecting configuration files
• QA engineers comparing test payloads
• Anyone who works with JSON daily

━━ OPEN SOURCE ━━

Clean, auditable code. Zero external dependencies.