Base64 Encoder / Decoder
Encode text to Base64 or decode Base64 back to plain text — instantly, in your browser
Invalid Base64 string
What Is Base64?
Base64 is a binary-to-text encoding scheme that converts data into a string of 64 printable ASCII characters. It is used extensively in web development: embedding images in HTML/CSS as data URIs, encoding authentication credentials in HTTP headers, and transmitting binary data through JSON APIs.
The encoded output is always larger than the input — approximately 33% larger — because every 3 bytes of input become 4 characters of output. For URL-safe Base64, the + and / characters are replaced with - and _ so the string can appear in URLs without percent-encoding. This variant is used in JWT tokens and many OAuth implementations.
Frequently Asked Questions
Base64 encodes binary data as printable ASCII text (64 characters: A–Z, a–z, 0–9, +, /). Used in email attachments, data URIs, and API payloads to safely pass binary through text-only systems.
Click "Decode", paste your Base64 string in the input box. The decoded text appears instantly. If the input isn't valid Base64, you'll see an error.
URL-safe Base64 swaps + → - and / → _ so the encoded string can appear in URLs without percent-encoding. JWT tokens use this variant.
No. Base64 is encoding, not encryption. Anyone can decode it without a key. Never use it to protect sensitive data. Use proper encryption (AES, RSA) for security.