Base64 Encoder & Decoder Online
Encode text to Base64 or decode Base64 to plain text. Supports UTF-8, URL-safe mode, and file encoding.
Runs in your browser. No data leaves your device.
Frequently Asked Questions
How does the Base64 Encoder work?
Your input string is converted to its UTF-8 byte sequence, then each group of 3 bytes is mapped to 4 Base64 characters using a 64-character lookup table (A-Z, a-z, 0-9, +, /). If the input length is not a multiple of 3, padding characters (=) are appended. Decoding reverses this process, mapping each group of 4 Base64 characters back to 3 bytes. URL-safe mode replaces + with - and / with _ per RFC 4648.
What is Base64 encoding used for?
Base64 converts binary data into ASCII text so it can be safely included in JSON, HTML, CSS, email, and URLs. Common uses include embedding images in CSS (data URIs), encoding email attachments, and passing binary data through text-only protocols.
Does Base64 encrypt my data?
No. Base64 is an encoding, not encryption. Anyone can decode a Base64 string back to the original data. It is meant for safe transport of binary data through text channels, not for keeping data secret.
Why is the Base64 output larger than the input?
Base64 encoding increases size by approximately 33% because it represents every 3 bytes of input as 4 ASCII characters. This overhead is the trade-off for safe text-based transport.