Base64 Encoder & Decoder

A Base64 converter lets you encode plain text or data into Base64 format, or decode a Base64 string back into readable text. Both operations happen instantly in your browser, so nothing you enter is sent to a server.

Base64 is an encoding scheme that represents binary data using a set of 64 printable ASCII characters. The name comes from the fact that it uses 64 characters: the letters A to Z and a to z, the digits 0 to 9, and the symbols + and /. An = sign is used for padding at the end of the output when needed.

When Would You Use Base64?

Base64 comes up more often than you might expect in web development and server work. Here are the most common situations:

Embedding images in HTML or CSS. Rather than linking to an image file, you can encode it as Base64 and embed it directly in your code as a data URL. This is useful for small icons or logos where you want to avoid an extra HTTP request.

API authentication. Many APIs use Basic Authentication, which works by encoding your username and password as a Base64 string and sending it in the request header. If you have ever seen an Authorization header that starts with “Basic”, that is Base64.

Email attachments. The MIME standard uses Base64 to encode binary files like images and documents so they can travel safely through email systems that only handle text.

Configuration files and environment variables. Some tools and services require credentials or certificates to be passed as Base64 strings, particularly in Docker, Kubernetes, and CI/CD pipelines.

Data URLs. You can encode small files as Base64 and use them directly in HTML, CSS, or JavaScript without needing a separate file request. This is common for inline SVGs and font files.

How Does Base64 Encoding Work?

The encoding process takes every three bytes of input and converts them into four Base64 characters. Because three bytes is 24 bits, and 24 bits splits neatly into four groups of six bits, each group maps to one of the 64 characters in the Base64 alphabet.

The result is always around 33% larger than the original input. That is the trade-off: Base64 makes binary data safe to transmit as text, but increases its size in the process.

If the input length is not a multiple of three, padding characters (=) are added to the end to make the output a multiple of four characters.

Is Base64 Secure?

No. Base64 is encoding, not encryption. It is simply a way to represent data in a different format. Anyone with a Base64 decoder, including this one, can reverse it instantly.

Never use Base64 to protect passwords, API keys, or any sensitive information. If you need to secure data, use proper encryption instead. Base64 is only for compatibility and formatting, not security.

Encode vs Decode: Which Do I Need?

Use Encode when you have plain text or data and need to convert it into a Base64 string. For example, if an API requires your credentials in Base64 format, you would encode them here.

Use Decode when you have a Base64 string and want to see what it contains. This is useful for inspecting API responses, reading config values, or checking what is inside a data URL.