What is Base64 encoding?
Base64 turns binary data into safe ASCII text using 64 characters. Learn what it is, why it is not encryption, and encode or decode text free.
Base64 is an encoding that represents binary data using only 64 printable ASCII characters (A–Z, a–z, 0–9, + and /). It exists so binary can travel safely through systems that only handle text — email bodies, JSON, data URLs, HTTP headers.
How it works
Base64 takes three bytes (24 bits) at a time and splits them into four 6-bit groups. Each 6-bit group (0–63) maps to one character in the Base64 alphabet. When the input is not a multiple of three bytes, the output is padded with = signs. The result is about 33% larger than the original — the cost of being text-safe.
It is encoding, not encryption
Base64 provides zero security. Anyone can decode it back to the original in one step. It is purely about transport, not confidentiality. If you need secrecy, encrypt first, then Base64 the ciphertext.
Where you see it
Data URIs (data:image/png;base64,…), Basic Auth headers, email attachments (MIME), and the header/payload of JWTs are all Base64. Base64URL is a variant that swaps + and / for - and _ so the output is safe in URLs.
Try it now — free, no signup
Use the Base64 decoder in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.