Base64 encoder and decoder

Base64 encoder and decoder guide

Base64 represents bytes with 64 characters: A-Z, a-z, 0-9, + and /. The = character is separate padding. It is used to carry original bytes as text in email attachments, JSON payloads, data URIs and small token representations. The Text tab converts UTF-8 strings to Base64 and back. The File tab accepts a chosen or dropped file for encoding, or restores a Base64 string as a downloadable file. Processing happens in your browser without sending the input or files to the Toolvil server.

Base64 is a reversible representation, not encryption. Do not use it to hide passwords, authentication tokens or personal data. This tool checks Base64 characters and padding, verifies whether decoded bytes form UTF-8 text, and normalizes URL-safe strings to standard Base64. Image previews show the beginning of a Data URI, but copying returns only the Base64 payload. To use it in HTML or CSS, add the data:image prefix for the actual image format yourself.

How to use

1. Choose Encode or Decode and Text or File input.
2. Enter a string in the Text tab or drag a file into the File tab.
3. Check the live result, original and result sizes, and size ratio.
4. Copy the result or convert it to URL-safe format if needed.
5. For a decoded file, choose an extension and select Download.

Text Base64 encoding and decoding

The Text tab encodes UTF-8 strings containing Korean, emoji and English as standard Base64, then decodes them again. Input and output are side by side. Use the middle ⇅ button to swap them and decode a result immediately. Live character counts and byte sizes help compare the data before and after conversion.

Encode files with selection or drag and drop

In the File tab, drag a file or click to choose one for Base64 encoding. All file formats are accepted, up to 10 MB. Conversion takes place inside the browser, so selecting a file does not send it to an external server.

Base64 images and Data URIs

Image file bytes are converted to a Base64 payload. The preview shows the beginning of a header such as data:image/png;base64,… and part of the payload. Copy returns the complete Base64 payload only. For a PNG, prepend data:image/png;base64, to the copied value for an HTML img src or CSS image URL. Check the actual format and MIME type rather than assuming them from the extension.

Decode Base64 and download a file

In Decode mode, paste Base64 into the File tab, choose an extension such as .png, .pdf or .zip from 11 options, then select Download to save the restored file. This is useful when you receive Base64 representing an image, document or archive and need its original bytes as a file.

URL-safe Base64 conversion and normalization

The +, / and = characters can be inconvenient in URLs and file names. URL-safe Base64 uses - and _ and can omit padding. Use the 🔗 URL-safe button to convert a result. URL-safe strings entered for decoding are normalized to standard Base64 automatically.

Base64 is not encryption

Base64 is an encoding that represents data as text, not encryption. Anyone can decode it to restore the original. Protect passwords, authentication tokens and personal data with actual encryption rather than Base64.

As its name suggests, Base64 represents values using 64 characters. To compare the same bytes in base 2, base 8 or base 16, use the number base converter. This helps inspect byte values from decoded data.

This utility converts Base64 representations and restores file bytes. It does not replace data security, integrity checks or virus scanning. Review untrusted Base64 and files separately before using them.