jsonyo · JSON Swiss-Army Knife

About

jsonyo is a free JSON Swiss-Army Knife for your browser. Five JSON tools in one popup, zero data leaves your computer, zero ads, zero account.

WHAT IT DOES

• Format — paste any JSON, get pretty-printed output with proper indentation. Two-space, four-space, or tab. Toggle line numbers.
• Validate — instant syntax check with line + column pointing at exactly where the problem is. No more guessing what "Unexpected token U at position 1247" means.
• Query — run JSONPath expressions ($.users[*].name), filter, recursive-descend, slice arrays, project fields. Get back the matching subset.
• Diff — side-by-side comparison of two JSON documents. Added / removed / changed paths called out, no eyeballing arrays line-by-line.
• Minify — strip whitespace, get the smallest valid JSON. Useful for production payloads and HTTP body size budgets.
• Stats — count keys, depth, types, longest path, biggest array. Quick structural overview before deeper editing.

WHY USE IT

Most online JSON formatters paste your data into a server somewhere — sometimes the wrong server. jsonyo runs entirely in your browser. Your JSON never leaves your machine. Open the network tab — you will see no outbound traffic at all. The manifest is open source so you can verify it yourself.

PRIVACY

• Zero data collection
• Zero outbound network requests
• Zero analytics, zero tracking, zero cookies
• Zero account, zero login
• Zero host_permissions — works only when you click the icon
• Manifest V3, declares data_collection_permissions: ["none"] per Mozilla 2026 standard

The same engine powers our open-source npm CLI (@v0idd0/jsonyo) and our WordPress plugin. Single source of truth across all three surfaces, MIT-licensed, auditable.

KEYBOARD SHORTCUTS

• Ctrl/Cmd+B — format
• Ctrl/Cmd+M — minify
• Ctrl/Cmd+Enter — apply current tool
• Tab — insert two spaces

ABOUT DEVELOPER

Built by vøiddo — a small studio shipping AI-flavoured products, free dev tools, Chrome extensions and weird browser games. We make tools we want to use ourselves. Free forever. No upsell. No "Pro" tier.