Free browser developer tool

JSON, YAML, TOML & Query String Converter

Edit either side. The other updates automatically.

Data stays on this device

Left editor

JSON

Valid JSON Ready to edit from either side.

83 characters · 83 B

Right editor

Query String

Valid Query String Ready to edit from either side.

65 characters · 65 B

Edit either side to convert

Plain text only · converts locally · maximum 1,000,000 characters or 1 MB

Move structured data between configuration files, API payloads, and search parameters without changing tabs. Both editors remain editable, so the side you touch last becomes the source.

Your data is not uploaded or saved. Parsing, validation, detection, and conversion happen inside this browser tab without an external API.

Quick guide

A two-way data workbench

  1. 1 Paste on either side. A full replacement paste can detect JSON, YAML, TOML, or a Query String automatically.
  2. 2 Edit in both directions. The latest editor becomes Source; the opposite editor receives the converted result.
  3. 3 Format, copy, or swap. Format cleans up the current syntax, while Swap exchanges formats, content, and direction together.

Conversion rules

Predictable formats, explicit limits

JSON & YAML

JSON uses strict browser parsing and two-space output. YAML uses the safe YAML 1.2 core schema, rejects multiple documents and custom tags, and limits alias expansion.

TOML

Tables and arrays of tables are supported. TOML output requires a top-level object and reports the exact path of null or another value that TOML cannot preserve.

Query String

Output contains only search parameters and starts with ?. Nested values use encoded bracket notation; repeated keys become arrays, and parsed values remain strings.

No silent data loss

Unsupported top-level shapes, nulls, empty collections, unsafe integers, invalid percent escapes, and lossy scalar types produce a visible error or warning instead of disappearing.

Safety by default

Plain text in, plain text out

Each source remains a normal textarea value. Pasted HTML is never rendered, and conversion errors are inserted as text. Query parsing rejects prototype-related keys, excessive depth, large array indexes, malformed UTF-8 escapes, and more than 1,000 parameters. The overall input limit is 1 MB or 1,000,000 characters, whichever is reached first.