URL serialization boundary · Updated November 6, 2026
URL Format / URL Formatter: Compare Parsed URL Parts and Serialization
Paste a URL to see its parsed parts and the browser's serialized spelling. People also call this a URL formatter when they need to inspect or compare a normalized URL. URL format is not only a visual pattern: parsing can normalize a hostname, preserve a query value, or rewrite escapes. This tool puts the original input beside the serialized URL so you can see what changed.
Four format changes worth checking
| Input | Serialized URL | Observed part |
|---|---|---|
https://Example.com:443/ | https://example.com/ | Hostname case and default HTTPS port normalize. |
https://example.com/a%2Fb | Path escape remains visible | A slash encoded inside a path segment is not a path separator. |
?q=a%20b~ | ?q=a%20b~ until searchParams mutates it | Reading a URL does not guarantee a rewrite; mutation is the event to test. |
?flag | ?flag | A valueless query key can remain distinct from an explicit empty value. |
Format is an observation, not a policy
A serialized result tells you what the URL implementation emitted. It does not say whether your application should accept the URL, follow it, or treat two spellings as equivalent. Keep parser behavior, encoding policy, and security allow-lists as separate checks.
Rerun the evidence
Download the Node regression script, fixtures and recorded results. Run node url-format-regression.cjs with Node v24.19.0 or a newer compatible release.
For malformed input, use the valid URL checker. For deliberate component encoding, use the URL encoder.