Free browser developer tool
JSON, YAML, TOML & Query String Converter
Edit either side. The other updates automatically.
Left editor
JSON
SourceRight editor
Query String
SourceEdit 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 Paste on either side. A full replacement paste can detect JSON, YAML, TOML, or a Query String automatically.
- 2 Edit in both directions. The latest editor becomes Source; the opposite editor receives the converted result.
- 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.
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