Conversion rulesDeep nesting uses the square-bracket convention (same as qs); arrays come in append / repeat-key / indexed styles. Parsing accepts a full URL (everything after the question mark), plus-sign spaces and repeated keys, with percent encoding handled automatically.

Query String

Load data

JSON

Converted output will appear here

URL params ⇄ JSON

Query String to JSON

Deep nesting / arrays / repeated keys · paste a full URL · two-way · local

🔒Processed locally in your browser — never uploaded or stored

No upload, no storage

JSON is processed in memory and never sent to a server.

Share via URL fragment

Share links encode data in the # anchor — never sent to a server.

Remember last edit

Optionally keep your last input locally; clear it with one click.

Why use JSON ⇄ Query String

Nesting survives

Nested objects are encoded with the bracket convention and parsed back into the same nested JSON — not a flatten-only toy.

Three array styles

Append, repeat-key or indexed array encoding, matching qs / PHP / Rails conventions.

Paste a full URL

No manual trimming: paste the whole URL and everything after the question mark is parsed, hash fragments ignored.

Controlled inference

Number / boolean / null inference can be toggled, and very long integers stay strings to keep precision.

Local · no upload

Query strings often carry tokens and other secrets; converting entirely in your browser is what keeps them safe.