When you’re building any web application, URL encoding isn’t just about “making things work,” it’s about making them work reliably and securely across all environments.
The main reasons why you should use urlencode are:
Reserved Characters – Certain characters have special meaning in URLs (e.g., &, =, ?, /). If you don’t encode them, the browser or server might misinterpret your link. For example, ?name=John&Doe could be parsed incorrectly without encoding &.
Non-ASCII and Spaces – URLs were originally designed for a limited character set (ASCII). Characters like spaces, accented letters (é, à), or symbols need encoding to ensure they’re transmitted correctly. While modern browsers often handle unencoded characters, not all servers or proxies do. That’s why %20 for space is still the safe option.
Security – Without proper encoding, you open doors for injection attacks. For example, if query parameters aren’t encoded, malicious users could inject scripts or unexpected input. Encoding helps prevent broken queries and reduces the risk of vulnerabilities like XSS.
Interoperability – Maybe your dev environment “just works” without encoding, but deploy the same app behind a load balancer, proxy, or CDN, and suddenly things break. Encoded URLs ensure consistency across browsers, servers, and APIs.
👉 When should you use it?
Anytime you’re dealing with dynamic input (user input, query strings, form values, filenames, API calls). In short: if it didn’t come hard-coded from you, encode it.
If you want a deeper dive with examples in Python, JavaScript, and best practices, I put together a guide here: https://urlencoderdecoder.com. It explains not just the “how” but also the “why” behind URL encoding and decoding.