URL Query String Generator
Build a URL with parameters without worrying about encoding. Enter name and value pairs, or paste a JSON object, choose how spaces and lists should be written, and get a correctly percent-encoded query string appended to your base URL. Lists and nested objects can be written in the bracket style of PHP and Rails, as repeated keys, comma-separated or with indexes.
- Runs in your browser
- No sign-up
- Free to use
How to use URL Query String Generator
- Enter the base URL.
- Add parameters as fields, or switch to JSON and paste an object.
- Choose how to encode spaces and lists.
- Copy the finished URL.
URL Query String Generator features
Correct encoding
Every name and value percent-encoded per RFC 3986.
Two space styles
%20 or + as HTML forms send.
JSON input
Nested objects and arrays flattened automatically.
Four list styles
Brackets, repeated keys, commas or indexes.
Base URL aware
Appends to an existing query and keeps the fragment.
Length check
Warns when the URL gets too long for some servers.
When to use URL Query String Generator
- Building API request URLs for testing.
- Creating links with tracking or filter parameters.
- Converting a JSON payload into GET parameters.
- Teaching how URL encoding works.
URL Query String Generator FAQ
Why must parameters be encoded?
Characters such as &, =, # and spaces have meaning in URLs. Encoding them as %26, %3D, %23 and %20 makes sure they are read as part of the value.
Should I use %20 or + for spaces?
Both are widely understood in query strings. %20 is the general URL standard; + is what HTML forms send. APIs usually document which they expect.
Which list style does my server expect?
PHP and Rails read brackets (a[]=1). Many Java and Go servers read repeated keys (a=1&a=2). Some APIs expect comma-separated values. Check the API documentation.
Why are brackets not encoded?
Browsers and servers accept [ and ] in query strings, and leaving them readable makes the URL easier to check. Their meaning is the same.
Is there a maximum URL length?
The standard sets none, but many servers and proxies limit URLs to around 8,000 characters, and some tools to about 2,000. Large data belongs in a POST body.
Is anything sent?
No. The URL is built in your browser.
Building URLs that survive the journey
A URL with parameters is easy to write by hand until a value contains a space, an ampersand, an equals sign or a non-English character. Then the URL breaks silently: the server reads a truncated value or an extra parameter. Encoding each name and value separately prevents that.
Percent-encoding replaces every character outside the unreserved set, letters, digits, hyphen, full stop, underscore and tilde, with a percent sign and two hexadecimal digits per byte of its UTF-8 representation. The generator applies this strictly, including to characters such as apostrophes and parentheses that some encoders leave alone.
Structured data needs a convention, because query strings are flat. The bracket notation of PHP and Rails, repeated keys and comma-separated lists all work, with different servers. JSON input lets you describe the data once and try the styles until the result matches what your server expects.
Keep URLs reasonably short and free of secrets. URLs appear in browser history, server logs and analytics; tokens and personal data belong in headers or request bodies, not in the query string.