Base64 Encoder & Decoder for Text, Files & Images
Encode and decode Base64 data instantly in your browser. Convert text, upload files, or generate Base64 strings from images without installing any software.
When you encode an image, the tool generates a data:image/...;base64, Data URI string.
You can embed it directly into HTML <img src="..."> tags or CSS files to display images without additional HTTP requests.
The decoder automatically detects Standard, URL-safe, and MIME Base64 formats.
Support is included for more than 20 character encodings, including UTF-8, EUC-KR, Shift_JIS, GBK, and Big5 for multilingual text conversion.
If your data contains special URL characters, try the URL Encoder & Decoder. For large image uploads, reduce file size first with the Image Compressor.
Why Your Base64 Result May Look Incorrect
If the decoded output appears empty or unreadable, check the character encoding setting first.
Using different charsets during encoding and decoding can corrupt Korean, Japanese, Chinese, and other multibyte characters.
If the input contains extra spaces or line breaks, enable the “Trim Leading & Trailing Whitespace” and “Ignore Spaces, Tabs & Line Breaks” options before trying again.
For large binary data, uploading the original file is usually more stable than pasting raw Base64 text.
Where Base64 Encoding Is Commonly Used in Development
Base64 is used in more areas of modern web development than many developers realize.
The header and payload sections of JWT tokens are encoded using URL-safe Base64.
It’s also common to convert binary files into Base64 strings when embedding them inside JSON responses for REST APIs.
Email attachments are transmitted as Base64 data under the MIME standard. Some database systems also store binary content as Base64 text instead of using BLOB fields.
You can inspect and verify encoded output directly with this converter.
Why Base64 Increases File Size
Base64 encoding increases file size by roughly 33% compared to the original data.
This is because 8-bit binary data is converted into 6-bit segments represented by 64 printable characters.
For small assets such as icons or inline images, embedding Base64 directly into code can be convenient.
However, encoding large files like high-resolution images or videos can significantly increase bandwidth usage.
For larger media files, serving them through standard file URLs is usually the more efficient approach.
Base64 Decoding — What Type of String Should You Paste?
You may come across Base64-encoded strings in API responses, raw email source data, JWT tokens, or exported application files.
Paste the encoded value into the decode tab to restore the original text or binary content.
Even strings delivered without Padding (=) can usually be processed using the automatic Padding correction feature.
If the decoded result does not display correctly, verify that the proper character encoding is selected. Using the wrong charset may cause Korean text or special characters to appear corrupted.
Base64 vs Other Encoding Methods
Base64, URL encoding, and Hex encoding all transform data into text form, but each method serves a different purpose.
Hex encoding represents each byte as two hexadecimal characters, making raw data easier to inspect manually but nearly doubling the total size.
Base64 is more compact than Hex and produces shorter strings for the same binary data.
URL encoding replaces unsafe URL characters using the %XX format. It is designed specifically for web addresses rather than converting entire binary files into text.
Choosing the right encoding method depends on how the data will be used.
Frequently Asked Questions
Standard Base64 uses the + and / characters.
Because these characters have special meanings inside URLs, Base64 values can break or be interpreted incorrectly when used directly in query parameters.
URL-safe Base64 replaces + with - and / with _.
This format is widely used in JWT tokens, OAuth authentication, and modern web APIs.
- Use the URL-safe option when including Base64 data inside URL parameters.
- This converter automatically detects both formats during decoding.
When an image is converted to Base64, it becomes a Data URI string.
This allows images to be embedded directly into HTML, CSS, or email templates without loading external image files.
- HTML:
<img src="data:image/png;base64,..."> - CSS:
background-image: url("data:image/...") - Email templates: Images can still appear even when external image loading is blocked
Because Base64 increases file size, it works best for icons and lightweight images. For larger files, reduce the image size first with the Image Compressor.
Base64 is not encryption. It is simply an encoding method that converts binary data into text format and does not provide any security protection.
Anyone can decode Base64 data and restore the original content, so passwords, personal information, or authentication tokens should never be protected with Base64 alone.
- If your goal is data protection, use proper encryption algorithms such as AES or RSA.
- Base64 is commonly used as a transport-friendly text format for encrypted or binary data.
Paste the Base64 string into the file decode tab and run the decoding process to display a download button.
Click the button to save the restored file to your device.
Image files can usually be previewed on screen before downloading.
MIME Base64 is the format defined by the email standard RFC 2045. It automatically inserts a line break every 76 characters in the encoded output.
Some email servers and SMTP systems cannot reliably process extremely long Base64 strings without line wrapping.
Use the MIME option when handling email attachments or SMTP-related data.
During decoding, automatic detection mode recognizes MIME Base64 automatically, so no additional settings are required.
Base64 is an encoding standard that converts binary data into text using letters, numbers, and symbols — a total of 64 printable characters.
It is commonly used to safely transmit binary content such as images, files, and audio in environments that only support text-based data.
- Email attachments using the MIME standard.
- Embedding Data URI images in HTML or CSS.
- Transferring binary data inside JSON or XML API responses.
- Encoding JWT token payloads.
Base64 is based on the international IETF RFC 4648 standard and is supported in nearly every modern development environment.
Base64 converts every 3 bytes (24 bits) of binary data into 4 text characters.
If the input length is not evenly divisible by 3, the remaining space is filled with = or ==. This is known as Padding.
Some systems intentionally transmit Base64 strings without Padding characters.
The automatic Padding correction feature in this converter can still decode Base64 data correctly even when Padding is omitted.
If you want to remove Padding manually, enable the “Remove Padding (=)” option during encoding.