Base64 Encoder/Decoder | Free, Open Source & Ad-free

You just pasted a Base64 string from an API response, but the text came back as garbled symbols. Or maybe you need to send binary data in a JSON payload without breaking the parser. Either way, you need a reliable Base64 encoder/decoder that works instantly and respects your privacy. Most online tools upload your sensitive data to unknown servers. That stops now. Here’s how to get perfect conversions every time, with full control over padding, line breaks, and URL safety.

A Base64 encoder converts binary or text data into an ASCII string using 64 characters (A-Z, a-z, 0-9, +, /). A decoder reverses the process. Use it to safely transmit data over text-based protocols like JSON, email, or HTTP headers.

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It works by taking three bytes (24 bits) of input data and splitting them into four groups of 6 bits each. Each 6-bit group maps to one of 64 printable characters.

The name “Base64” comes from those 64 possible output values: uppercase A–Z (26), lowercase a–z (26), digits 0–9 (10), plus + and / (2 more). Padding characters (=) are added to make the output length a multiple of 4.

Base64 is not encryption – it’s an encoding. Anyone can decode it. Its purpose is safety, not secrecy.

Here is exactly how a Base64 encoder/decoder transforms data:

1. Take raw input – Example: the ASCII text "Man" (hex: 4D 61 6E).


2. Convert to binary – 01001101 01100001 01101110 (24 bits total).


3. Split into 6-bit chunks – 010011 010110 000101 101110.


4. Map to Base64 alphabet – 010011 = decimal 19 → T | 010110 = decimal 22 → W | 000101 = decimal 5 → F | 101110 = decimal 46 → u


5. Result – "TWFu"

To decode, reverse the process: map each character back to its 6-bit value, concatenate, then split into 8-bit bytes.