Free Online Base64 Decoder
Batch decode Base64 strings to text, files, and images instantly
Drag & drop multiple text files containing Base64 here
or click to select files (max 20)
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Need to Encode Instead?
Use our Base64 Encoder/Decoder tool for both encoding and decoding.
How to Use the Base64 Decoder
- Paste your Base64 string into the input field. This can be a simple encoded text, a data URI, or any valid Base64 sequence.
- Select the output mode — Text (for readable strings), File (for binary downloads), or Image (for image data URIs).
- Use Batch Mode to select multiple text files containing Base64 and decode them all at once into a ZIP file.
- Check URL-safe if your input uses - and _ instead of + and / characters.
- Click "Decode" to instantly convert the Base64 string back to its original form.
- Copy or download the decoded result using the buttons below the output.
Common Base64 Use Cases
- Email attachments: MIME encoding uses Base64 to transmit binary files through email protocols.
- Data URIs: Embed images, fonts, and other assets directly in HTML and CSS using Base64.
- API responses: Many REST APIs return binary data as Base64 encoded strings in JSON responses.
- Authentication tokens: JWT tokens contain Base64-encoded header and payload sections.
- Database storage: Binary data stored in text-only database columns is often Base64 encoded.
What Is Base64 Encoding?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters: uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), plus (+), and forward slash (/). The equals sign (=) is used as padding when the input length is not a multiple of 3 bytes.
Base64 was originally designed to allow binary data to be safely transmitted through text-based protocols like email (SMTP) and HTTP. It increases the data size by approximately 33% but ensures that all characters in the encoded output are universally safe for transmission across different systems and protocols.
Base64 Character Set
| Range | Characters | Values |
|---|---|---|
| A-Z | 26 uppercase letters | 0-25 |
| a-z | 26 lowercase letters | 26-51 |
| 0-9 | 10 digits | 52-61 |
| + / | 2 symbols (or - _ for URL-safe) | 62-63 |
| = | Padding character | N/A |
Frequently Asked Questions
atob() function. No data is ever transmitted to our servers. Your Base64 strings never leave your device, making this tool safe for decoding sensitive information like API keys, authentication tokens, or private documents.data:image/png;base64,), the decoder will render a preview and let you download the image file. This works with all common image formats including PNG, JPEG, GIF, WebP, and SVG.