Base64 Encoder & Decoder Pro

Why use this tool?

• Base64 turns binary or special characters into plain letters and digits, which is how images get embedded in CSS and HTML and how many APIs carry credentials and tokens.
• Developers regularly need to see what a Base64 string actually contains when debugging a request, an email header or a configuration file.
• Writing a small image straight into a stylesheet or an email template avoids an extra file request, and needs a data URI.
• A JWT is three Base64URL sections, and reading the header and payload is the first step in checking what a token claims.

How to use Base64 Encoder

1. Choose Encode or Decode at the top of the Text panel.
2. Paste your text. In Encode mode this is plain text; in Decode mode it can be Base64, a data URI or a JWT.
3. Tick the URL-safe alphabet option if the data uses - and _ in place of + and /, or if you want that form as output.
4. Read the result on the right, along with input bytes, output length and the size overhead. Press Copy or Download.
5. To encode a file, drop it onto the area labelled Drop a file or click to browse (up to 8 MB). You get a data URI and a Copy raw Base64 button.
6. If decoding a data URI, press Save as a file to download the original bytes.

Features

• Encode and decode with UTF-8, so non-English text and emoji round-trip correctly
• Optional URL-safe alphabet for encoding and decoding, with padding removed on output
• File to data URI, with a preview for images and a button to copy only the Base64 part
• Decode a data URI back to a downloadable file, with a file extension chosen for common types
• Detects a JWT and displays its decoded header and payload as formatted JSON
• Warns if the text you are encoding already looks like Base64
• Input size, output size and overhead percentage

Supported formats

Text in and out, and any file type as input for a data URI, up to 8 MB. Decoded data URIs download with a matching extension for PNG, JPEG, GIF, WebP, SVG, PDF, JSON, plain text, CSV and HTML, and as .bin for anything else.

Tips

• Base64 is encoding, not encryption. Anyone can decode it, so never use it to hide a password.
• Expect the encoded form to be about a third larger than the original; the Overhead figure shows the exact amount.
• If decoding fails, check whether the string came from a URL or a JWT. Those use the URL-safe alphabet, so tick that option.
• The JWT view only reads the two readable sections. It does not check the signature, so a decoded token is not proof that it is genuine.

Frequently asked questions