Encode text to Base64 or decode Base64 strings back to text.
What Base64 Actually Is (And What It Isn't) Encode text or binary data to Base64 format, or decode Base64 back to its original form. Base64 is one of the most common encoding schemes on the internet — and one of the most frequently misunderstood. Base64 represents binary data using only 64 printable ASCII characters: the 26 uppercase letters, 26 lowercase letters, 10 digits, and the characters + and /. The = sign is used for padding. The name comes from the fact that the alphabet has exactly 64 characters, and each Base64 character encodes 6 bits of the original data (2^6 = 64). Why does this exist? The problem Base64 solves is a 1980s infrastructure problem. Early email protocols — SMTP specifically — were designed to transmit plain text. They could not reliably handle the full range of byte values, particularly bytes with the high bit set (values above 127) or certain control characters. Binary file attachments, image data, and other non-text content would get corrupted in transit. Base64 solved this by converting arbitrary binary data into a safe subset of ASCII characters that any text-based protocol could transmit without corruption. MIME, the standard that governs email attachments, still uses Base64 today. You encounter Base64 constantly even if you do not recognize it. Data URI schemes that embed images directly in HTML or CSS use Base64 (you have seen strings starting with data:image/png;base64,...). JSON Web Tokens (JWTs), which authenticate users in web applications, are Base64-encoded JSON. HTTP Basic Authentication encodes the username and password as Base64 before sending them in the Authorization header. Configuration files and API responses frequently embed binary blobs as Base64 strings. The critical misconception: Base64 is not encryption. It provides absolutely no security whatsoever. Any person or system that receives a Base64-encoded string can decode it instantly with no key, no password, and no special knowledge. The encoding is completely reversible and publicly documented. Do not use Base64 to protect sensitive data, hide credentials, or obscure information — it will fail immediately if anyone looks.
Early email protocols in the 1980s could only handle plain ASCII text. Base64 converts binary data (images, files, arbitrary bytes) into printable ASCII characters so it can be safely transmitted through text-only protocols like SMTP.
No. Base64 is an encoding scheme with no security properties. Anyone can decode it instantly with no key or password. It is not encryption, not obfuscation, and not a security measure. Never use it to protect credentials or sensitive information.
Base64 appears in data: URIs that embed images in HTML, in JSON Web Tokens (JWTs) for authentication, in HTTP Basic Auth headers, in email attachments via MIME encoding, and in many API responses that return binary data as strings.