Base64 Encoder / Decoder

About Base64

Base64 is an encoding scheme that converts binary data into a string of ASCII characters. It uses a set of 64 characters (A–Z, a–z, 0–9, +, /) plus = for padding.

Common uses

• Data URIs — embedding images directly in HTML or CSS (src="data:image/png;base64,…")
• JWT tokens — the header and payload sections of a JSON Web Token are Base64url-encoded
• Email attachments — MIME encoding transmits binary files as Base64 text
• API responses — some APIs encode binary blobs (PDFs, images) as Base64 strings

Important notes

Base64 is an encoding, not an encryption. Anyone can decode it instantly. Never use it to "hide" sensitive information — use real encryption (AES, RSA) for that.

Encoded output is roughly 33% larger than the original. A 3-byte input becomes 4 Base64 characters. Padding characters (= or ==) are added to make the length a multiple of 4.