What is Base64?
Base64 represents binary data using only 64 safe characters (A–Z, a–z, 0–9, + and /, with = as padding). It is used wherever binary or arbitrary text has to travel through systems that only handle plain text: email attachments (MIME), data URLs in HTML and CSS, HTTP Basic authentication headers, JSON Web Tokens, and API fields that carry files or keys. Base64 output is about 33% larger than the input.
Base64 is an encoding, not encryption — anyone can decode it. Do not use it to protect passwords or secrets.
Why UTF-8 matters
The browser’s built-in btoa() function fails on characters outside Latin-1, such as Hindi, Chinese or emoji. This tool converts text to UTF-8 bytes first, which is what servers, command-line tools (base64) and programming languages expect, so नमस्ते 👋 encodes and decodes correctly. When decoding, it tells you if the result is binary data rather than readable text.
URL-safe Base64 (base64url)
Standard Base64 uses + and /, which have special meanings in URLs. The URL-safe variant (RFC 4648 §5) replaces them with - and _ and usually drops the = padding. JWTs use this variant. The decoder accepts both forms automatically, and also ignores whitespace and data:...;base64, prefixes.
Example
Text
Hello, World!Base64
SGVsbG8sIFdvcmxkIQ==Frequently asked questions
Why does decoding show strange characters?
The Base64 data is probably a binary file (an image, PDF or compressed data) rather than text. The tool warns you when the decoded bytes are not valid UTF-8.
What does the = at the end mean?
It is padding that makes the length a multiple of 4. One = means the last group encoded 2 bytes; == means it encoded 1 byte.
Can I encode a file?
You can upload text files. For images or other binary files, use a dedicated file-to-Base64 tool.
Is my text uploaded?
No. Encoding and decoding happen in your browser.