Format rules
- Spaces become %20 or + depending on context
- Reserved characters must be encoded
- Do not double encode
Valid example
q=hello%20world&tag=a%2Fb
Invalid example
q=hello world&tag=a/b
Common errors
- Assuming URL encoding accepts syntax from a similar format
- Using the wrong encoding or line ending
- Copying invisible characters from rich text
- Testing only the happy path and not parser errors
Online validation and conversion
Compared with nearby formats
URL encoding should be chosen for the parser and ecosystem that will consume it. Prefer strict formats for APIs, human-friendly formats for ops config, and signed formats only when verification is required.