What is Base64 encoding used for?

Base64 encoding converts binary data (images, files) into ASCII text format. Common uses: embedding images in HTML emails (data URIs), storing binary data in JSON/XML, encoding API responses, and transmitting binary data over text-only protocols. Base64 increases file size by about 33%.

Is Base64 encoding secure or encrypted?

No, Base64 is encoding, not encryption. It's easily decoded by anyone. Never use Base64 for security—it's for data transmission, not protection. For sensitive data, use proper encryption (AES, etc.) before encoding if needed.

What's the maximum file size I can encode?

The practical limit is about 10MB per file, limited by browser memory. Base64 increases file size by 33%, so a 10MB file becomes ~13MB. For larger files, use file upload APIs or desktop tools. For images in emails, keep under 100KB for best compatibility.

Can I embed Base64 images in HTML emails?

Yes, most modern email clients support Base64 data URIs for images. Format: . However, some email clients (older Outlook versions) don't support it. Test before sending. Keep images under 100KB for best compatibility.

Why is my Base64 string so long?

Base64 encoding increases file size by approximately 33% (3 bytes become 4 Base64 characters). A 1MB file becomes ~1.33MB when Base64-encoded. This is normal. For large files, consider using regular file uploads instead of Base64 encoding.

What is the difference between standard and URL-safe Base64?

Standard Base64 uses characters +, /, and = which have special meaning in URLs. URL-safe Base64 replaces + with -, / with _, and may omit the trailing = padding. Use URL-safe Base64 when the encoded string will appear in URLs, query parameters, or filenames.

Why does Base64 encoding increase file size?

Base64 represents every 3 bytes of binary data as 4 ASCII characters, resulting in approximately 33% size increase. This overhead is the trade-off for being able to transmit binary data over text-only channels (like email or JSON). For small assets like icons, the overhead is negligible compared to the saved HTTP requests.

Can I encode files (not just text) to Base64?

Yes. The tool supports both text-to-Base64 and file-to-Base64 conversion. You can drag and drop any file (images, PDFs, documents) and get the Base64-encoded string. This is commonly used for embedding small images in HTML/CSS, encoding email attachments, and storing binary data in JSON.

Base64 Encoder/Decoder - Free Online Tool

When to Use This Tool

Use this when:

You need to embed small images in HTML emails (Base64 data URIs work in most email clients)
You want to embed images in CSS files without external image files
You're working with API responses that return Base64-encoded data
You need to encode text or files for transmission over text-only protocols
You're creating data URIs for embedding resources in HTML/CSS
You need to decode Base64 strings from API responses or configuration files
You're working with JSON data that contains Base64-encoded content

Don't use this if:

You need to encode files larger than 10MB (Base64 increases size by 33%, use file uploads instead)
You're encoding images for websites (use regular image files for better performance)
You need to encode binary files for production APIs (use proper file upload endpoints)
You require Base64 encoding for very large datasets (use streaming or chunked encoding)
You need to encode sensitive data (Base64 is not encryption—it's encoding, not secure)

What is a Base64 Encoder/Decoder?

A Base64 encoder/decoder converts data between its original form and Base64 encoding — a method of representing binary data as ASCII text. Our tool handles both encoding and decoding entirely in your browser, ensuring your data stays private.

Base64 encoding is fundamental in web development and data transfer: embedding images in HTML/CSS as data URIs, encoding email attachments (MIME), transmitting binary data over text-based protocols like JSON APIs, and encoding authentication tokens. Understanding and working with Base64 is essential for anyone building web applications.

This tool is vital for web developers embedding images inline to reduce HTTP requests, API developers debugging encoded payloads and authentication headers, email developers working with MIME-encoded attachments, DevOps engineers encoding secrets for environment variables and Kubernetes configs, and security researchers analyzing encoded data.

Compared to command-line tools (echo "text" | base64 — requires terminal access), browser console methods (btoa/atob — doesn't handle Unicode properly), or online encoders that may log your data, PureXio's tool handles Unicode text correctly, supports file-to-Base64 conversion, and provides instant bidirectional encoding/decoding.

The tool automatically detects whether input is Base64-encoded and suggests decoding. It supports both standard and URL-safe Base64 variants and shows the encoded/decoded output size for comparison.

Best for: encoding/decoding text and files to/from Base64. Supports Unicode, URL-safe Base64, file conversion. Instant processing. Fully private.

How to Encode/Decode Base64

Select mode: Encode (text/file to Base64) or Decode (Base64 to text)

Enter text or upload file (for encoding), or paste Base64 string (for decoding)

Copy the encoded/decoded result or download as file

Common Use Cases

Encode a 50KB logo image to Base64 for embedding in HTML email (avoids external image hosting)

Decode Base64-encoded API response to view the actual data content

Encode a small icon (20KB) to Base64 for embedding in CSS file (data URI)

Decode Base64 string from configuration file to view original content

Encode text credentials to Base64 for basic authentication headers

Create data URI for small image (under 50KB) to embed directly in HTML/CSS (base64-encoded PNG/JPG)

Decode Base64-encoded image from API to save as regular image file

Features

Encode text and files to Base64 format

Decode Base64 strings back to original text or files

Support for images, text files, and binary data

Generate data URIs for HTML/CSS embedding

Process files up to 10MB (limited by browser memory)

100% private—all encoding/decoding happens in your browser

No registration or file uploads to servers

Limitations & Constraints

Maximum file size: 10MB (browser memory limit). Base64 increases size by 33%, so 10MB becomes ~13MB.

Not secure: Base64 is encoding, not encryption. Don't use for sensitive data protection.

Large Base64 strings: Files over 5MB create very long Base64 strings that may cause issues in some systems.

Email compatibility: Some email clients (older Outlook) don't support Base64 data URIs.

Performance: Base64-encoded images in websites load slower than regular image files. Use for emails, not websites.

Troubleshooting

Base64 encoding fails or browser becomes slow

Solution: Large files (over 5MB) can cause browser performance issues. Try encoding smaller files first, or use desktop tools for large files. Close other browser tabs to free up memory. Base64 increases file size by 33%, so very large files may exceed browser limits. Prevention: Keep files under 5MB for reliable browser-based encoding.

Base64-encoded image doesn't display in email

Solution: Some email clients (especially older Outlook versions) don't support Base64 data URIs. Test with multiple email clients. Keep images under 100KB for best compatibility. Consider using regular image hosting for emails instead. Prevention: Test Base64 images in target email clients before sending. Use regular images for maximum compatibility.

Decoded Base64 doesn't match original file

Solution: Ensure the Base64 string is complete and hasn't been truncated. Check for extra whitespace or line breaks that need to be removed. Verify the Base64 string is valid (only contains A-Z, a-z, 0-9, +, /, and = padding). Some systems add line breaks—remove them before decoding. Prevention: Copy Base64 strings carefully, ensuring no truncation or extra characters.

Base64 string is too long for my system

Solution: Base64 increases file size by 33%. Very large files create extremely long strings. Consider chunking the data or using file upload APIs instead. For images, use regular image files rather than Base64 for better performance. Prevention: Keep files under 1MB for Base64 encoding. Use file uploads for larger files.

Encoded image doesn't work in CSS data URI

Solution: Ensure the data URI format is correct: data:image/png;base64,ENCODED_DATA (replace png with actual format: jpg, gif, webp). Include the semicolon and comma. Verify the Base64 string is complete. Some CSS parsers are strict about formatting. Prevention: Use the correct data URI format. Test in target environment.