Base64 Encoder / Decoder
Encode text or files to Base64 and decode Base64 strings back to original content. Supports Unicode text and file uploads. All processing happens in your browser for complete privacy and security.
Base64 is a binary-to-text encoding scheme that converts binary data into ASCII characters. Our free Base64 Encoder/Decoder tool lets you instantly convert text and files to Base64 format and decode Base64 strings back to their original content. Base64 is widely used for embedding images in HTML/CSS, encoding email attachments (MIME), storing binary data in JSON/XML, transmitting data in URLs, and encoding authentication credentials. This tool supports full Unicode text and file uploads up to 5MB. All encoding and decoding happens entirely in your browser using native JavaScript APIs—your data is never sent to any server, ensuring complete privacy and security.
100% Client-Side Processing
All Base64 encoding and decoding happens directly in your browser using native JavaScript APIs (btoa,atob,FileReader). Your data never leaves your device. This tool works offline after the page loads.
How to Use the Base64 Encoder / Decoder
- Select your mode using the toggle at the top: "Encode" converts text/files to Base64, "Decode" converts Base64 back to text.
- Enter your input in the left textarea. For encoding, type or paste any text including Unicode characters and emojis.
- Upload a file (encode mode only) by clicking "Upload File" to convert images, documents, or any file to Base64.
- View the result instantly in the right textarea as you type or after file upload.
- Copy the output using the "Copy Output" button, or use "Swap & Decode/Encode" to quickly reverse the operation.
What is Base64 Encoding?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters: A-Z, a-z, 0-9, +, and /. The equals sign (=) is used for padding. This encoding increases data size by approximately 33% but ensures safe transmission through text-only channels.
Example:
Text: Hello World
Base64: SGVsbG8gV29ybGQ=
Common Use Cases
Data URIs
Embed images directly in HTML/CSS as Base64 data URIs
Email Attachments
MIME encoding for email attachments and content
Basic Auth
HTTP Basic Authentication header encoding
JSON/XML Storage
Store binary data in text-only formats
URL Parameters
Safely pass binary data in URL query strings
LocalStorage
Store binary data in browser localStorage
Related Tools
Need to generate checksums? Try our Hash Generator for MD5, SHA-1, and SHA-256 hashes. For URL-safe encoding, check out our URL Encoder/Decoder (coming soon).
Frequently Asked Questions
Is Base64 encoding the same as encryption?▼
No, Base64 is not encryption. It's simply an encoding scheme that converts binary data to text format. Anyone can decode Base64 without any key or password. Base64 is used for data transport, not security. If you need to protect sensitive data, use proper encryption algorithms like AES. Base64 is often used after encryption to safely transmit encrypted binary data as text.
Why does Base64 increase data size?▼
Base64 uses 6 bits per character (2⁶ = 64 characters) to represent 8-bit bytes. This means every 3 bytes (24 bits) of input become 4 characters (24 bits) of output. The result is approximately 33% larger than the original. Additionally, padding characters (=) may be added to make the output length divisible by 4. This overhead is the trade-off for text-safe encoding.
What's the difference between Base64 and Base64URL?▼
Standard Base64 uses + and / characters, which have special meaning in URLs. Base64URL (also called URL-safe Base64) replaces + with - and / with _ to make the encoded string safe for use in URLs and filenames. Base64URL is commonly used in JWTs (JSON Web Tokens) and URL parameters. This tool uses standard Base64; for URL encoding, consider using encodeURIComponent() after Base64 encoding.
Can I encode/decode images with this tool?▼
Yes! Use the "Upload File" button to select any image (PNG, JPG, GIF, etc.) and convert it to Base64. The output can be used as a data URI in HTML/CSS. For example:<img src="data:image/png;base64,YOUR_BASE64_HERE" />Note that large images will produce very long Base64 strings, which may not be practical for embedding.
Why do I get an error when decoding?▼
Decoding errors typically occur when: (1) The input contains invalid characters—Base64 only allows A-Z, a-z, 0-9, +, /, and = for padding. (2) The string length isn't divisible by 4. (3) The decoded content is binary data (like an image) rather than text. If you're decoding binary data, the raw bytes can't be displayed as text. Try removing any whitespace or line breaks from your input.
Frequently Asked Questions
❓ Is this tool free?
Yes! All our tools are completely free. No registration, no hidden charges, no ads. Just open and use.
🔒 Is my data safe?
Absolutely. All calculations happen in your browser. We don't store, send, or track any of your data. Everything is processed locally on your device.
📱 Can I use this on mobile?
Yes! All our tools are fully responsive and work perfectly on smartphones, tablets, and desktops.
🌐 Do I need internet?
No! Once the page loads, you can use the tool completely offline. All calculations happen in your browser without any server connection.