URL Encoder & Decoder — Components & Query Strings

How it works

Component mode uses encodeURIComponent and decodeURIComponent. Use it for an individual parameter value, not to preserve the structure of a whole URL. Query parsing accepts a query string with or without a leading question mark and returns an ordered JSON array of string pairs. Query building accepts the same pair structure and produces form-style encoded parameters.

Limits and behavior

Component decoding keeps a literal plus sign. Query parsing treats plus as a space, while %2B represents a literal plus. Duplicate keys, order and empty values are preserved in the pair array. Malformed percent escapes and invalid Unicode are reported rather than silently repaired. Query building uses spaces as plus signs. Do not paste a complete URL into query parsing.

Example

Parse q=hello+world&tag=a%2Bb to get [["q","hello world"],["tag","a+b"]]. Build that array to reverse the operation. Inputs are limited to 200,000 characters; no URL is opened or fetched.

Assumptions and limitations

Start with Load example to see the expected input shape. Replace the example with your own text and choose the relevant operation. Editing an input invalidates the previous output so an old result cannot be copied as if it were current. Copy and download buttons become available after a successful run. Clear removes the visible inputs and output from the page. Limits keep small development tasks responsive; use a local editor or dedicated command-line utility for very large files. A successful transformation does not validate your application logic or make untrusted data safe to execute.

Sources

MDN Web Docs

Frequently asked questions