Base64 Decode

About Our Base64 Decoder Tool

Meet Base64 Decode, a simple online tool that does exactly what it says: decodes Base64 encoded data quickly and easily, right in your browser. Decode your data into a human-readable format without hassles.

Base64 encoding schemes are commonly used when there is a need to encode binary data, especially when that data needs to be stored and transferred over media designed primarily for text. This encoding helps ensure that the data remains intact without modification during transport. Base64 is frequently used in applications like email via MIME, embedding images or other data directly into web pages (Data URLs), and storing complex data in XML or JSON.

Features

Our tool offers several features to make decoding simple and effective:

• Client-Side Decoding & Security: All decoding happens directly within your web browser using JavaScript. Your data is never sent to our servers for processing, ensuring your information remains completely private and secure. This tool supports the common UTF-8 character set, allowing proper display of letters and symbols from various languages. It also robustly handles common Base64 variations, including whitespace, padding issues, and URL-safe characters (-, _).
• Decode Each Line Separately: The encoded data sometimes consists of multiple, independent entries separated by newlines. Check this option if you intend to decode such data, processing each line individually. When unchecked, the tool will treat the entire input as a single Base64 block (ignoring internal newlines and whitespace as per the standard) or prompt you if multi-line input is detected without this option selected.
• Advanced History: Your recent decodes are automatically saved in your browser's local storage for easy access. You can assign an optional title to each entry for better organization; if you don't provide one, the tool defaults to using the beginning of the Base64 string. Browsing your history is straightforward with simple pagination controls and an option to display 5, 10, or 25 entries per page. History items are initially shown concisely with just the Title and Date, but you can click the expand button to reveal a collapsible view containing the full Base64 string and action buttons. From this expanded view, you can quickly Load the data (including the title) back into the decoder, Copy Input (the original Base64), Copy Output (the decoded text), or Delete the entry using a confirmation prompt. Additionally, you can use the checkboxes to select multiple history items and delete them in bulk via a secure modal confirmation.

Safe and Secure

Your privacy is paramount. As mentioned, all decoding operations are performed client-side. While the website itself is accessed over secure SSL encrypted connections (HTTPS), no data you paste into the decoder is transmitted externally for the decoding process itself. We do not keep or inspect the contents of the submitted data. Read our Privacy Policy for more details.

Completely Free

Our Base64 Decoder tool is completely free to use. No need to download or install any software for this common task.

Details of Base64 Decoding

Base64 decoding is the process of converting a string of Base64 characters back into its original binary data format. It essentially reverses the Base64 encoding scheme. This is commonly required when retrieving original data that was transmitted or stored using Base64, such as extracting attachments from MIME emails, interpreting Data URLs in web pages, or reading binary data stored in text formats like XML or JSON.

The Base64 Decoding Process

To decode a Base64 string, each character in the string is mapped back to its original 6-bit index value using a standard character set. These 6-bit sequences are then regrouped into 8-bit bytes to reconstruct the original binary data. Decoding must also correctly handle padding characters (=), which indicate the end of the data and how many bits were added during encoding, as well as variations in the character set used, such as the standard set (A-Z, a-z, 0-9, +, /) or the URL-safe variant (A-Z, a-z, 0-9, -, _). Our tool handles these common variations automatically.

Example: MIME Base64 Character Set Table (Used for Decoding)

This table shows the standard 64 characters and their corresponding index values (0-63). During decoding, each character from the input Base64 string is looked up in this table to find its 6-bit value, which is then used to rebuild the original data.