jsonyo · JSON Swiss-Army Knife

Format, validate, query, diff, minify JSON. Zero data leaves your browser. Free forever.

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.