Base64 Encoder/Decoder Articles

Base64 vs Base64url: Why `+`, `/`, and `=` Break URLs, and Why JWTs Use a Different Alphabet

Standard Base64's `+`, `/`, and `=` characters all have special meaning in URLs — which is why a Base64-encoded JWT pasted directly into a URL can silently corrupt, and why Base64url exists as a separate, URL-safe alphabet. Here's exactly which characters differ, why JWTs require Base64url specifically, how padding works and why Base64url commonly omits it, and how to tell the two variants apart.

Jun 13, 2026

How Email Attachments Work: MIME Encoding, Base64, and Why Binary Files Need Encoding

Email attachments work because MIME uses Base64 to encode binary files as ASCII text — a system designed in 1992 when email could only carry 7-bit ASCII. Here's how MIME multipart email works, why binary needs encoding, the 33% Base64 overhead on attachment sizes, and how the same system handles HTML form file uploads.

Jun 11, 2026

Data URLs and Base64: When to Embed Resources Inline vs Link to Them

Base64 Encoder/Decoder Articles

Base64 vs Base64url: Why `+`, `/`, and `=` Break URLs, and Why JWTs Use a Different Alphabet

How Email Attachments Work: MIME Encoding, Base64, and Why Binary Files Need Encoding

Data URLs and Base64: When to Embed Resources Inline vs Link to Them

Base64 Encoder/Decoder — What It Is, When to Use It & Why It's Not Encryption

Base64 Encoder/Decoder — How It Works & Real Developer Uses