Base64 Encoder / Decoder

What is Base64 Encoder / Decoder?

Base64 Encoder converts arbitrary text or binary data into the Base64 alphabet defined by RFC 4648, and decodes Base64 strings back to their original form. It supports both standard Base64 and the URL-safe variant that replaces + and / with - and _. The tool handles UTF-8 multi-byte characters correctly and can process file uploads, converting them to Base64 data URIs suitable for embedding in HTML or CSS.

Web developers embedding assets inline, API developers constructing authentication headers, and DevOps engineers encoding secrets for configuration files. The tool runs entirely in your browser — your data never leaves your device.

How to Use Base64 Encoder / Decoder

1. Type or paste your text into the input area for encoding, or paste a Base64 string for decoding
2. Choose between standard Base64 or URL-safe Base64 mode depending on your use case
3. For file encoding, drag and drop a file onto the upload zone to generate the Base64 representation
4. Review the output which updates in real time as you modify the input
5. Copy the result to clipboard with one click or download it as a text file

Common Use Cases

• Encoding binary image data into Base64 for inline embedding in HTML img tags
• Decoding Base64 strings from API responses to inspect raw content
• Preparing Basic Auth credentials by encoding username:password pairs
• Converting small SVG files to Base64 data URIs for use in CSS background-image properties
• Encoding email attachments in MIME format for SMTP message construction

Pro Tips

• Base64 encoding increases data size by approximately 33 percent — avoid it for large files where a direct binary transfer would be more efficient
• Use URL-safe Base64 (RFC 4648 Section 5) when embedding encoded data in query parameters or filenames to avoid character escaping issues
• For images under 10 KB, inline Base64 data URIs can reduce HTTP requests, but larger images should be served as separate files for caching benefits

Why Use This Tool?

• Privacy-first: All processing happens locally in your browser. No data is transmitted to any server.
• No installation required: Works in any modern browser on desktop or mobile.
• Completely free: No account, no credit card, no usage caps.
• Fast and reliable: Powered by modern Web APIs for near-instant results.

Related Concepts

Learn more about related topics: RFC 4648, Data URI, MIME encoding, Base32.

Frequently Asked Questions