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URL Parameter Builder

This free URL parameter generator — also called a URL parameter builder or query string builder — takes your key=value pairs, percent-encodes them for you and assembles a ready-to-paste query string and full URL, without touching your URL by hand. Everything happens locally in your browser, with nothing uploaded. For campaign tracking tags such as utm_source and utm_medium, use the UTM Builder instead.

Base URL (optional)

Query string–

Full URL–

What is a URL parameter builder?

A URL parameter builder constructs the query part of a web address from a list of keys and values. A URL parameter is a key=value pair that appears after the question mark, and multiple pairs are joined with an ampersand, like ?page=2&sort=desc&lang=en. The important part most people skip is encoding: spaces, plus signs, ampersands, equals signs and non-ASCII characters are not safe in a URL, so each key and value is percent-encoded. This tool does that automatically, using encodeURIComponent, so your parameter values arrive on the other side intact. You can optionally provide a base URL and the tool appends the query string correctly — adding a ? if there is none, or an & if the base already has one. This matters for building tracking links, API calls, campaign URLs, and any time you need a query string that is guaranteed to be valid and safe to share.

How to use

Optionally paste a base URL.
Add key/value rows and fill them in.
The query string and full URL build instantly; copy them.

Example

Add the pairs page = 2, q = hello world and lang = en. The query string becomes ?page=2&q=hello%20world&lang=en, and with the base https://example.com/search it becomes https://example.com/search?page=2&q=hello%20world&lang=en.

Common use cases

Building UTM and marketing campaign URLs with the correct tracking parameters.
Constructing API request URLs that need multiple encoded query values.
Creating shareable search or filter links with predictable parameters.
Testing how an app or page responds to different query strings.

Pro tips

Leave the key and value fields filled in; rows with an empty key are skipped automatically.
Add or remove rows freely — the query string and full URL rebuild instantly.
Provide a base URL to get a complete, paste-ready address with correct ? or & placement.
Use UTM Builder if you want the standard utm_source, utm_medium and utm_campaign fields prefilled.

FAQ

What is a URL parameter?

A URL parameter is a key=value pair that appears in the query string after the question mark, separated by ampersands, and passes data to a page or API.

Why are my parameters encoded?

Special characters like spaces, ampersands and equals signs are percent-encoded so the URL stays valid when a browser or server parses it.

What is percent encoding?

Percent (URL) encoding replaces reserved characters with a percent sign and a hex code, so %20 is a space and %26 is an ampersand.

How do I add more parameters?

Click Add parameter to insert another key/value row; remove a row with the small x button. Empty keys are ignored.

What happens if I provide a base URL?

The tool builds the full URL for you — inserting a ? if the base has no query yet, or an & if it already does.

Is it private?

Yes — it runs entirely in your browser and nothing is uploaded.

Is it free?

Yes, free and unlimited with no signup.

What is the difference between a query string and a URL parameter?

A URL parameter is a single key=value pair; the query string is the whole series of parameters after the ? in a URL.