Percent-encoded strings use %HH sequences where HH is the hex value of a byte.
This decoder calls decodeURIComponent() which reverses the encoding — %20 → space, %26 → &, %3F → ?
Multi-byte sequences like %C3%A9 are reassembled into UTF-8 characters (é in this case).
If the decoded string is a valid URL, the tool also breaks it into components: protocol, host, path, and query parameters.