Base64 Encoder/Decoder
Encode text to Base64 or decode a Base64 string.
How to Calculate
Base64 is an encoding scheme that converts binary data into an ASCII string.
Common use cases:
• Email attachment transfer (MIME)
• Data URIs (embedding images directly in HTML/CSS)
• Passing API authentication tokens
• Transmitting binary data over text-based protocols
Base64 uses 64 characters: A-Z, a-z, 0-9, +, / and uses = for padding.
Example
FAQ
Is Base64 encoding the same as encryption?
No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string without a key. For protecting sensitive data, use encryption algorithms like AES or RSA.
How much larger does Base64 make the data?
Base64 increases size by approximately 33%. Every 3 bytes of input become 4 Base64 characters. For example, a 1 MB file becomes roughly 1.33 MB after encoding.
Why does Base64 decoding fail?
Common causes: (1) the string contains characters outside A-Z, a-z, 0-9, +, /, =; (2) incorrect padding (=); (3) attempting to decode URL-safe Base64 (which uses - and _ instead of + and /) with a standard decoder.
What is the difference between Base64 and Base64URL?
Base64URL replaces + with - and / with _, and omits padding (=). This makes it safe for use in URLs and filenames. It is commonly used in JWT tokens.