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What Is Base64 Encoding? Explained for Developers
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters (A-Z, a-z, 0-9, +, /). It is used when binary data must be transmitted over text-only channels.
Why Base64 Exists
Email, JSON, XML, and URLs are text-based and cannot safely carry raw binary data. Base64 converts bytes into printable characters, expanding size by roughly 33%.
URL-Safe Base64
Standard Base64 uses + and / which are problematic in URLs. URL-safe Base64 replaces + with - and / with _. JWT and many web APIs use this variant.
Common Uses
Email attachments (MIME), data URIs in HTML/CSS, JWT token segments, embedding images in JSON, storing binary in databases, and API credential transport.
Frequently Asked Questions
Is Base64 encryption?
No. Base64 is encoding, not encryption. It is trivially reversible. Do not use Base64 for security — use proper encryption.
What are the = characters at the end?
Padding characters. Base64 output length must be a multiple of 4. = or == are added to pad the final block.