Web / URLs
Query String Builder
Build or edit a URL's query string as key and value rows, with proper encoding, repeated keys, and a choice of + or %20 for spaces; paste an existing URL to split it.
Query String Builder: Each key and value is percent-encoded so that characters such as &, =, ?, and # inside a value cannot break the address. Form encoding writes spaces as +, as browsers do when submitting forms; strict encoding writes %20 and escapes everything except letters, digits, and - . _ ~. Repeated keys are kept in order, the way many servers read lists. Runs 100% locally in your browser with zero server file uploads.
- Category
- Web tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
https://example.com/search?q=red+shoes&size=10
Keys and values are encoded for you, so & = ? and # inside a value cannot break the address. Repeated keys are kept, in order, as many servers read them as a list.
Characters that need encoding
& separates parameters, = separates a key from its value, # starts the fragment, and + means a space in form encoding, so a value containing any of them must be encoded: a&b becomes a%26b. Non-ASCII letters are encoded as UTF-8 bytes, so é becomes %C3%A9.
To inspect any URL's parts, use the URL parser; for campaign links, the UTM builder.
Length limits
Browsers handle very long URLs, but servers, proxies, and some services cut them off at a few thousand characters, and search engines prefer short ones. Put large or private data in a POST request body instead of the query string, which appears in logs and browser history.
How to use it
- Paste a URL to split its parameters into rows, or start from scratch.
- Add, edit, or remove keys and values.
- Copy the finished URL; choose + or %20 for spaces.
Privacy & limitations
Everything runs in your browser; the URL is never requested.
Related tools
Frequently asked questions
+ or %20 for spaces?
Both mean a space in a query string to most servers; use %20 when a service's documentation asks for it, or in parts of the URL other than the query.
How do I send a list?
Repeat the key, such as size=10&size=11; some frameworks expect size[]=10&size[]=11 instead.
What is the difference from UTM links?
UTM links are query strings with five standard keys for campaign tracking; the UTM builder fills those in for you.
Free tool · runs in your browser · no account required