Query Parameter Builder
Build a URL with encoded query parameters.
About Query Parameter Builder
The Query Parameter Builder assembles a URL from a base address and a list of key–value pairs, encoding every value correctly as you go. Hand-building query strings is where broken requests come from: a raw ampersand splits a value, an unencoded space breaks the URL, a stray ? starts the query twice.
Add and remove parameters freely and copy the finished URL — correct percent-encoding included — into your HTTP client, test or browser. It is also a clean way to document exactly which request reproduces a bug.
How to use
- Paste the endpoint into "Base URL" (for example https://api.example.com/search).
- Add each key and value under "Query parameters" — values are encoded for you.
- Click "+ Add parameter" for more rows, or ✕ to remove one.
- Copy the finished address from "Built URL".
Frequently asked questions
Which characters in parameter values cause the most trouble?
Ampersands (split the value into a new parameter), equals signs, spaces, plus signs and anything non-ASCII. Any of them unencoded silently changes the request — the builder encodes them all correctly.
Can I repeat the same key, like tags=a&tags=b?
Yes — add two rows with the same key. Repeated keys are the most common convention for multi-value parameters, though some APIs expect tags[]= or comma-separated values instead; check the contract you are testing.
Does parameter order matter?
Servers should not care, but cache keys, signature calculations and some poorly built endpoints do. If you suspect order sensitivity, building the same URL with reordered rows is an easy experiment.