Base64 vs Base64URL

Base64 and Base64URL encode binary data into ASCII, but they are not interchangeable. Base64 uses the + and /characters and typically includes = padding. Base64URL replaces + with - and / with_, and allows omitting padding to be URL- and cookie-safe. This avoids reserved characters that can be reinterpreted by browsers, proxies, or frameworks.

Use Base64URL for web tokens and URLs (e.g.,JWT). Use Base64 for general file encodings, email (MIME), and CLI tools that expect the classic alphabet. Many decoders are lenient and accept both alphabets, but you should output the format your consumers expect to avoid subtle bugs.

Related tools

Try: Base64, Base64URL, JWT

FAQ

What characters differ between Base64 and Base64URL?

Base64 uses + and / while Base64URL uses - and _. Base64URL may also omit trailing = padding for compactness.

Can I safely use standard Base64 in URLs?

It is risky because +, /, and = have special meaning in URLs and HTTP forms. Prefer Base64URL for URL, cookie, and JWT contexts.