About Base64
What is Base64 encoding?
Base64 is an encoding scheme that represents binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It's commonly used to embed binary data (images, files) in text-based formats like JSON, XML, HTML, and email.
When should I use URL-safe Base64?
URL-safe Base64 replaces + with - and / with _. Use it when encoding data that will appear in URLs, cookies, or filenames — where the standard + and / characters would need to be percent-encoded.
Is my data sent to any server?
No. All encoding and decoding happens entirely in your browser using JavaScript. Your data never leaves your device. This tool has no backend, no logging, and no analytics on your input content.
Why does Base64 increase file size?
Base64 encodes every 3 bytes of input as 4 characters of output — a ~33% overhead. This is the trade-off for making binary data safe to transmit in text-only protocols.
What's the padding (=) at the end?
Padding ensures the Base64 output length is a multiple of 4. If the input length isn't divisible by 3, one or two = characters are added. Some contexts (like JWT) omit padding — use the "No padding" option for this.