How are arrays represented?

Use empty brackets like roles[]=admin&roles[]=editor, or numeric indices like roles[0]=admin.

Are values URL-decoded automatically?

Yes, percent-encoding and + for spaces are decoded when converting to JSON, and re-encoded going the other way.

Can I swap direction quickly?

Yes, the swap button flips the mode and carries over the current output as the new input.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

Query String Converter

Convert between URL query strings and JSON, with nested bracket support.

Support

Works Offline

Privacy First

No Login

No API

Query string

Input

JSON

Output

JSON

{
  "user": {
    "name": "Ada",
    "roles": [
      null,
      null,
      "editor"
    ]
  },
  "page": "2"
}

About the Query String Converter

Convert a query string into structured JSON (supporting bracket notation like a[b][]=1) or serialize JSON back into a query string, useful for debugging API requests and form submissions.

Popular uses

query string
json
querystring
url encode
bracket notation

Examples

Nested query to JSON

JSONuser[name]=Ada&user[roles][]=admin

Output

JSON{"user":{"name":"Ada","roles":["admin"]}}

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser