Standard vs URL-Safe Base64: Key Differences Explained
Standard Base64 uses + and / which break URLs. URL-safe Base64 replaces them with - and _. Learn when each variant applies and how to convert.
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Tags: encoding, developer-tools, base64
Standard vs URL-Safe Base64: Key Differences Explained If you've decoded a JWT, implemented OAuth PKCE, or read through the WebAuthn spec, you've encountered Base64URL — the URL-safe variant of Base64 encoding. It looks almost identical to standard Base64 but has two character substitutions that matter a lot in web contexts. This post explains what changes, why it was necessary, and where each variant belongs. The Two Characters That Changed Everything Standard Base64 uses (plus) at index 62 and (slash) at index 63. Base64URL replaces them: → (hyphen) → (underscore) Additionally, Base64URL typically omits the padding characters. That's the entire difference. The algorithm is the same, the bit manipulation is the same, the 3-to-4 encoding ratio is the same. Only the output characters…
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