What is Base64 encoding?

Base64 is a binary-to-text encoding scheme that represents binary data as a string of ASCII characters. It uses 64 characters (A-Z, a-z, 0-9, +, /) to represent data, making it safe to transmit through text-based protocols like email and HTTP headers.

Does Base64 encoding encrypt my data?

No. Base64 is an encoding, not encryption. Anyone can decode a Base64 string back to its original form. It is designed for safe data transport, not for security. If you need to protect data, use proper encryption.

Why is my Base64 output longer than the original text?

Base64 encoding increases data size by approximately 33%. Every 3 bytes of input become 4 Base64 characters. This overhead is the trade-off for making binary data safe to transmit as text.

What is URL safe Base64?

Standard Base64 uses + and / characters, which have special meaning in URLs. URL safe Base64 replaces these with - and _ so the encoded string can be used directly in URLs and filenames without additional encoding.

Is my data sent to a server?

No. Encoding and decoding happen in your browser with JavaScript's built-in btoa() and atob() functions. Open your browser's network tab while using the tool. You will see zero requests. Your text never leaves your device.

Base64 Encode/Decode

Base64 Encode and Decode Online

Base64 is a binary to text encoding that represents any data (text, images, binary files) as a string of printable ASCII characters. Paste text to encode it, or paste a Base64 string to decode it back. Everything runs locally in your browser.

How to Use

Paste or type your text into the input field
Select a mode: Auto (detects whether to encode or decode), Encode, or Decode
Copy the result from the output field using the Copy button

How Base64 Works

Base64 encoding converts binary data into a text representation using 64 printable ASCII characters. The encoding process takes every 3 bytes (24 bits) of input and splits them into 4 groups of 6 bits. Each 6-bit value maps to one of 64 characters: A-Z, a-z, 0-9, +, and /. If the input length is not a multiple of 3, padding characters (=) are added.

This encoding is commonly used for embedding images in HTML/CSS via data URIs, encoding email attachments (MIME), transmitting binary data in JSON or XML payloads, and storing complex data in URL parameters or cookies.

UTF-8 Support

This tool fully supports UTF-8 text, including emoji, CJK characters, and other multibyte Unicode. The input text is first encoded to UTF-8 bytes using the TextEncoder API before Base64 encoding, ensuring correct round trip conversion for any language or symbol set.

JWTs use a variant called Base64URL that swaps +/ for -_ and drops padding. The JWT Decoder handles that automatically. If you need to encode special characters for URLs instead of binary transport, the URL Encoder uses percent encoding, which is the standard for query parameters and path segments.

File and Image Conversion

This tool handles text input. To convert files and images to Base64, use the dedicated converters below. They support drag and drop, image preview, and output as plain Base64, data URIs, or CSS background declarations:

Image to Base64: convert any image (JPG, PNG, SVG, WebP, GIF)
PDF to Base64: encode PDFs for APIs and database storage
File to Base64: encode any file type
Base64 to Image: decode and preview Base64 image strings
Base64 to File: decode Base64 back to downloadable files
CSS Background Image: generate ready to paste CSS with inline images
Data URI Generator: create data: URLs from any file