What is Base64? Encoding explained

Base64 is a binary-to-text encoding that represents arbitrary bytes using a 64-character alphabet (A-Z, a-z, 0-9, +, /) plus optional = padding. Developers use it whenever a channel expects text but the payload may contain bytes that would break that channel.

What Base64 looks like

Encoding the UTF-8 string Hello, Jigglify! produces:

SGVsbG8sIEppZ2dsaWZ5IQ==

Decoding that string restores the original text. The output is longer than the input - typically about 33% larger - because each group of three bytes becomes four ASCII characters.

Base64 is not encryption

Anyone who sees Base64 can decode it with a standard library or an online tool. It hides nothing. If you need confidentiality, use real cryptography (TLS in transit, encryption at rest, password hashing for credentials). Encoding and encryption solve different problems - see Base64 vs encryption.

When developers use Base64

• Data URLs for small images or fonts embedded in HTML or CSS
• HTTP Basic Authentication header credentials
• Embedding binary-safe snippets inside JSON or XML
• Debugging opaque tokens that are Base64-shaped (distinct from Base64URL in JWTs)

Standard Base64 vs Base64URL

Some protocols (including JWT segments) use Base64URL, which swaps + and / for - and _ and often omits padding. Jigglify's Base64 tool focuses on standard Base64. For JWTs, the JWT decoder is a better fit.

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Next reads: How to encode and decode Base64 · Base64 vs encryption