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About this tool
Build a correctly percent-encoded query string from JSON, choosing how arrays, nested objects, spaces and unicode are serialised.
This tool turns a JSON object into a correctly percent-encoded URL query string, following RFC 3986's rule that everything outside the unreserved set (letters, digits, hyphen, dot, underscore, tilde) must be escaped when used as data. Developers building API calls, webhooks or tracking URLs choose how arrays and nested objects are flattened — repeated keys, brackets, indices, comma, space or pipe delimited — and whether a space becomes %20 or a form-urlencoded plus sign.
Open Query Parameter Encoder Builder on AltFTool — it loads instantly in your browser.
Paste your code or data sample into the workspace.
Pick the format, conversion, or analysis you need.
Copy the polished result straight back into your project.
Repeat, brackets, indices, comma, space and pipe formats matching qs, PHP, Rails and OpenAPI 3 conventions.
Optionally encodes the five characters encodeURIComponent leaves alone, as OAuth 1.0a signing requires.
Flags query strings over the 2,083-character IE limit and nginx's 8 KB default request line buffer.
Everything except the RFC 3986 unreserved set — letters, digits and - . _ ~ — must be encoded when it appears as data. Reserved delimiters like & = ? # and any non-ASCII character are escaped as the percent-encoded bytes of their UTF-8 form, so an ampersand becomes %26 and é becomes %C3%A9.
%20 is the RFC 3986 percent-encoding and is always safe in a URL; + means a space only in application/x-www-form-urlencoded data, the format HTML forms submit. If the server decodes with strict URL rules, a + arrives as a literal plus sign — so use %20 unless you know the endpoint expects form encoding.
There is no standard — the server decides. The most portable form is repeating the key (tags=new&tags=sale), which Express, Go, Rails and most Java frameworks parse natively; PHP needs empty brackets (tags[]=new), and OpenAPI 3 also defines comma, space and pipe delimited styles for scalar lists.
The HTTP specification sets no limit, but implementations do: Internet Explorer capped URLs at 2,083 characters, nginx's default request-line buffer is 8 KB, and many CDNs reject longer requests with a 414 error. If your query approaches those sizes, send the data in a POST body instead.