Input — Plain Text
0 chars · 0 bytes
Output — Base64
0 chars
How to use this tool
1
Choose Mode
Select Encode to convert text/file to Base64, or Decode to reverse it.
2
Select Options
Pick your variant (Standard, URL-Safe or MIME), encoding, padding, and output format.
3
Enter Input
Type or paste text, or switch to File mode and upload any file up to 50 MB.
4
Get Output
Result appears instantly. Copy to clipboard or download as a file.
Frequently Asked Questions
What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It is widely used in email attachments, data URIs, and API payloads where binary data must be transmitted over text-based channels.
What is URL-Safe Base64?
URL-Safe Base64 (RFC 4648 §5) replaces the + character with - and the / character with _, making the encoded string safe to use directly in URLs and filenames without percent-encoding. It is commonly used in JWT tokens and OAuth flows.
Is my data sent to any server?
No. All encoding and decoding is performed entirely in your browser using JavaScript. Your text and files never leave your device and are never transmitted to Usely.in or any third party.
Why does Base64 output look longer than the input?
Base64 encodes every 3 bytes of input into 4 characters of output, resulting in approximately 33% overhead. For example, a 1 KB file becomes roughly 1.37 KB when Base64-encoded.
What is MIME Base64 and when is it used?
MIME Base64 (RFC 2045) uses the standard Base64 alphabet but inserts a CRLF line break every 76 characters. It is the format used for email attachments and multipart MIME messages.