What is Base64 Encoder/Decoder?

A Base64 encoder/decoder is a free online tool that converts text or binary data to Base64 encoding and decodes Base64 strings back to their original format for data transmission and storage.

How do I use this Base64 Encoder/Decoder?

Type or paste your text into the input field and click Encode to convert to Base64, or paste Base64 data and click Decode to revert it. The result appears instantly in the output area.

Is this Base64 Encoder/Decoder free?

Yes, this tool is completely free to use with no signup required.

Base64 Encoder/ Decoder

Encode text to Base64 or decode Base64 back to text.

Encode Decode

Input

Output

Select mode, enter text, and click Convert.

How to Use This Tool

Paste the source string or data into the Base64 Encoder input box above.
The Base64 Encoder processes the input instantly and shows the result in the output box below.
Copy the encoded or decoded result with one click, or switch direction to reverse the operation.

Common Use Cases

Email attachments: MIME-encoded email bodies use Base64 to safely transmit binary attachments through 7-bit SMTP infrastructure.
Data URIs: Embed small images directly in CSS or HTML using data:image/png;base64,... to reduce HTTP requests on landing pages.
API authentication: Encode "username:password" for HTTP Basic Auth headers, or pass binary payloads through JSON-only APIs.

Frequently Asked Questions

Why does Base64 output use roughly 33% more characters than input?

Base64 encodes every 3 bytes of binary data into 4 ASCII characters (6 bits each), so output size is ceil(n/3) * 4. A 300 KB image becomes a 400 KB Base64 string. Add gzip on top for transport to recover most of the overhead.

What's the difference between standard and URL-safe Base64?

Standard Base64 (RFC 4648 section 4) uses + and / which are reserved in URLs. URL-safe Base64 (section 5) substitutes - and _ and drops the = padding. JWTs use URL-safe Base64; choose the variant matching your downstream consumer.

Can I Base64-decode any string?

Only strings whose length is a multiple of 4 (or with proper = padding) and that contain only valid Base64 characters. Invalid input throws an error. Whitespace and line breaks are stripped before decoding, so wrapped Base64 from email headers works fine.