Web & Network

Query String Builder

Parse, edit, and build URL query strings. Live-updating with encode/decode toggle.

How to use this tool

  1. Pick a mode with the tabs: Parse to break apart an existing link, or Build to construct one from scratch.
  2. In Parse, paste a full URL or query string into URL or Query String — its parameters appear in the Key-Value Pairs table and the result updates instantly.
  3. Toggle URL-decode values to see values in human-readable form, or leave it off to keep them encoded.
  4. Edit any key or value inline, or hit Del to drop a pair — the query string re-renders as you type.
  5. In Build, add an optional Base URL, type a Key and Value, then press Add; repeat for each parameter and use URL-encode values to control encoding.
  6. Grab the result with Copy Query String (just the ?key=value part) or Copy Full URL (base URL included).

Why this tool is helpful

Debug tracking & analytics links

Paste a marketing URL and see every utm_ and tracking parameter broken out into editable rows, instead of squinting at one long string.

Build standards-compliant URLs

Construction goes through URLSearchParams, so reserved characters are encoded correctly and the resulting URL stays valid.

Stop hand-encoding values

Spaces, &, =, and non-ASCII characters are percent-encoded for you, eliminating the mistakes that break manual query strings.

Test API endpoints fast

Change a parameter's value and copy the new URL without touching your code or fiddling with the address bar.

Split base URL from query

The parser separates the path from everything after the first ?, so you can edit the two parts independently.

Stay private

All parsing and building runs client-side in your browser. Nothing is uploaded, logged, or sent to a server.

FAQ

What is a query string?

The part of a URL after the ?, made of key=value pairs joined by & — for example ?name=John&age=30.

How does it parse and build?

It uses the browser's URLSearchParams API, plus encodeURIComponent/decodeURIComponent, to split a string into pairs and serialize them back out.

Why does my value contain %20 or +?

URLs only allow certain characters, so spaces and reserved characters get percent-encoded. A space is commonly written as + (or %20) inside a query string.

What does the "URL-decode values" toggle do?

Checked (the default), values are shown URL-decoded and your edits are re-encoded when the query string is rebuilt. Uncheck it to keep values exactly as they were parsed.

What's the difference between "Copy Query String" and "Copy Full URL"?

Copy Query String copies only the ?key=value portion. Copy Full URL prepends the base URL — either the one you set, or the part before the ? you pasted.

Can I paste a full URL into Parse mode?

Yes. It splits at the first ?, treats everything before it as the base URL, and parses the rest as the query string.

Does my data leave my browser?

No. All processing is client-side; your URLs and parameters are never sent to, stored on, or logged by a server.