Question 1

What is Base64 encoding?

Accepted Answer

Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters (A–Z, a–z, 0–9, +, /). It is widely used to embed binary payloads inside text protocols like JSON, XML, email (MIME), and Data URIs where binary bytes are not safe to transmit directly.

Question 2

What is URL-safe Base64?

Accepted Answer

URL-safe Base64 replaces the characters + and / with - and _, and omits trailing = padding. This makes the output safe to use directly in URLs, query parameters, JWT tokens, and filenames without further escaping.

Question 3

Is my data private when using this tool?

Accepted Answer

Yes — encoding and decoding happen entirely in your browser using the Web APIs btoa, atob, TextEncoder, and TextDecoder. Nothing is ever uploaded to a server. You can verify by disabling your network connection; the tool still works.

Question 4

Can I encode a file as Base64?

Accepted Answer

Yes. Click "Upload file" and the tool will read your file as text and place the contents into the input area. For binary files (images, PDFs), the recommended workflow is to use the URL-safe option and copy the result directly into your code or Data URI.

Question 5

Why does my decoded text look garbled?

Accepted Answer

That usually means the input is not valid Base64 or was encoded from binary (non-text) data. Verify that the input contains only Base64 characters and that the source was a UTF-8 text string. If it was binary (e.g. an image), decoding it as text will not produce readable output.

Question 6

Why is Base64 output longer than the input?

Accepted Answer

Base64 represents every 3 input bytes using 4 output characters. The output is always about 33% larger than the original. That is the cost of making binary data safely embeddable in text formats.

Base64 Encoder & Decoder

Fully Private

URL-safe Mode

File Uploads

Frequently Asked Questions

What is Base64?

When should I use URL-safe Base64?

Why does the output grow by ~33%?

Can I decode binary like images here?