JSONsmith Open editor
JSON spec compliant · RFC 8259

A precise toolbench for JSON.

Pretty print, minify, validate with line-accurate errors. Convert between JSON, YAML, and TOML — without leaving your browser.

Input Output Indent

    
Ready
Validate first

Catch trailing commas, dangling brackets, and dupe keys before they hit production.

Convert losslessly

Map between JSON, YAML, and TOML where the spec allows; warnings if a feature can't survive.

Stays local

Your payload never leaves the page. Perfect for sensitive configs.

Why JSONsmith

Because pasting your secrets into a random "JSON formatter" website should not be a thing. Open this page once, work forever — even offline.

Tiny & fast

Single static page, no analytics, no trackers, sub-100ms cold start. Validation handles megabyte-scale documents.