ENCODING GUIDE · 7 MIN READ

Base64 vs URL encoding: choose the right representation

Base64 and URL encoding both turn data into transport-friendly text, but they solve different problems. Selecting the wrong one produces unreadable parameters or corrupted bytes rather than added security.

Use percent encoding inside URLs

URL encoding replaces characters that are unsafe or structural inside a component. Encode the parameter value, not the full URL, so separators such as slash, question mark and ampersand keep their roles.

Use Base64 to represent bytes as text

Base64 maps binary bytes to a restricted alphabet. It is common in data URLs, email formats and API payloads, but increases size and may require a URL-safe alphabet in tokens.

Handle Unicode through bytes

Text must first be encoded, usually as UTF-8, before Base64 conversion. Mismatched character encodings cause corrupted output even when the Base64 syntax is valid.

Worked example

The URL value 'a & b' becomes 'a%20%26%20b'. Its UTF-8 Base64 representation is different because Base64 represents all bytes, not just URL-reserved characters.

Limitations to review

• Both encodings are reversible.
• Neither provides confidentiality or integrity.
• Base64URL and standard Base64 alphabets differ.