Base64 Encode & Decode

How to encode or decode Base64

1. Choose Encode to turn text into Base64, or Decode to turn Base64 back into readable text.
2. Type or paste into the left box. With Convert as I type on, the result updates instantly.
3. Tick URL-safe if the value goes into a URL, a file name or a JWT. Decoding accepts both standard and URL-safe input automatically.
4. To embed an image or any other file, click Encode a file. You get a ready-to-use data: URI.

What is Base64?

Base64 is a way to write binary data using only 64 safe characters: A-Z, a-z, 0-9, + and /, with = as padding. It exists because many systems, such as email, JSON, HTML attributes and HTTP headers, were designed for text and can corrupt raw bytes. Encoding the bytes as Base64 lets them travel safely through those systems and be decoded on the other side.

Every 3 bytes of input become 4 characters of output, so Base64 data is about a third larger than the original. That trade-off is fine for small values like tokens, icons and credentials in headers, but not for large files.

Common uses

• HTTP Basic auth. The Authorization: Basic header carries username:password encoded in Base64.
• Data URIs. Small images and fonts can be embedded straight into HTML or CSS as data:image/png;base64,..., saving a request.
• JWT tokens. The header and payload of a JSON Web Token are base64url-encoded JSON. Decode them here to inspect the claims.
• Email attachments. MIME encodes attachments in Base64 so they survive mail servers.
• APIs. Many APIs accept file uploads as Base64 strings inside a JSON body.

Base64 is not encryption

Anyone can decode Base64 in a second, so it gives no protection at all. Never use it to hide passwords, API keys or personal data. If you need secrecy, use real encryption and always send data over HTTPS.

Unicode and emoji

The browser's built-in btoa() function fails on characters outside Latin-1, such as emoji or Urdu text. This tool converts text to UTF-8 bytes first, so Salam 👋 or سلام encode and decode correctly. If you decode Base64 that holds binary data rather than text, you will see a warning instead of garbled characters.

Receiving form data without a server

If you only need visitors to send you a message from your website, you do not have to encode or decode anything yourself. A hosted form backend like formvoxo receives normal HTML form posts and emails each submission to you. See how it works.

Want the full guide? Read Base64 Encoding Explained: How It Works and When to Use It.

Frequently asked questions