Free Online Base64 Encoder & Decoder

Encode and decode Base64 strings online for free. Convert text to Base64 or decode Base64 back to plain text instantly. Perfect for developers working with APIs, data transmission, email attachments, HTML/CSS embedding, and secure data transfer.

Key Features

🔐 Encode to Base64

Convert plain text to Base64
Real-time encoding as you type
Support for any text input
Handles special characters
UTF-8 encoding support

🔓 Decode from Base64

Decode Base64 to plain text
Instant validation
Error detection
Invalid character warnings
Automatic format detection

⚡ Real-Time Processing

Auto-encode/decode on input
300ms debounce for performance
No manual button clicks needed
Instant feedback
Live character count

📊 Statistics

Input character count
Output character count
Size ratio percentage
Real-time updates
Encoding efficiency metrics

💾 Export Options

Download as .txt file
Export as .html file
Save as .json format
One-click copy to clipboard
Multiple format support

🔄 Utility Features

Swap input/output instantly
Sample text templates
Clear all button
Mode switching (encode/decode)
Dark mode support

Why Use Our Base64 Tool?

100% Free & Unlimited: Encode and decode unlimited text without registration, subscriptions, or size restrictions.

Complete Privacy: All encoding and decoding happens in your browser using JavaScript. No data is uploaded to servers or stored anywhere.

Instant Processing: Real-time encoding and decoding with automatic conversion as you type or paste content.

Developer Friendly: Built for developers with features like swap, sample data, multiple export formats, and live statistics.

Error Detection: Automatic validation when decoding with clear error messages for invalid Base64 strings.

Mobile Responsive: Works perfectly on desktop, tablet, and mobile devices with touch-optimized interface.

How to Encode to Base64

Select Encode Mode: Click the "🔐 Encode" button to switch to encoding mode.
Enter Text: Paste or type your plain text into the input textarea.
Auto-Encode: The tool automatically encodes your text in real-time as you type.
Review Output: See the Base64 encoded result in the output panel with character counts.
Copy or Download: Click "Copy" to clipboard or "Download" to save as TXT, HTML, or JSON file.

How to Decode Base64

Select Decode Mode: Click the "🔓 Decode" button to switch to decoding mode.
Paste Base64 String: Paste your Base64 encoded string into the input textarea.
Auto-Decode: The tool automatically validates and decodes the Base64 string.
Check for Errors: If the Base64 is invalid, you'll see an error message explaining the issue.
Use Decoded Text: Copy the decoded plain text or download it in your preferred format.

What is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts binary data into a text format using 64 ASCII characters (A-Z, a-z, 0-9, +, /). It's designed to safely transmit data over channels that only support text, such as email systems, URLs, HTML, CSS, JSON, and XML.

Base64 Character Set:

Uppercase Letters: A-Z (indexes 0-25)

Lowercase Letters: a-z (indexes 26-51)

Digits: 0-9 (indexes 52-61)

Special Characters: + (index 62), / (index 63)

Padding Character: = (used at the end for alignment)

Common Use Cases for Base64

Email Attachments: Encode binary files (images, PDFs, documents) as Base64 text for safe transmission via email protocols (MIME). Email systems were designed for text, so Base64 allows binary data to be sent as text.

Embed Images in HTML/CSS: Encode images as Base64 data URIs to embed directly in HTML or CSS files, reducing HTTP requests and improving load times for small images, icons, and logos.

API Data Transfer: Encode binary data, credentials, or tokens for transmission through REST APIs, webhooks, and web services. Commonly used in authentication headers and API keys.

JSON Data: Since JSON only supports text, Base64 allows binary data (images, files, encryption keys) to be included in JSON payloads without causing parsing errors.

URL Parameters: Encode data for safe inclusion in URLs. While URL encoding is preferred for URLs, Base64 can encode complex data structures for query parameters.

Database Storage: Store binary data in text-based database fields. Useful for CLOB/TEXT columns that don't support binary storage or for database systems with limited BLOB support.

Configuration Files: Encode sensitive data (passwords, keys, certificates) in YAML, JSON, or XML config files that only support text.

Perfect For

Web developers embedding images
API developers & integrators
Backend developers
DevOps engineers
Email system administrators
Database administrators

Security professionals
Data analysts
QA testers
System integrators
Students learning encoding
Technical writers

Base64 vs Other Encoding Methods

Base64 vs Hex Encoding: Base64 is more compact (33% overhead vs 100% for hex), making it more efficient for large data. Hex uses 0-9 and A-F (16 characters), while Base64 uses 64 characters for better compression.

Base64 vs URL Encoding: URL encoding (percent-encoding) is designed specifically for URLs and encodes special characters as %XX. Base64 encodes entire data as text, making it better for binary data but not URL-safe without modification (Base64URL variant).

Base64 vs Encryption: Base64 is NOT encryption. It's encoding - anyone can decode Base64. For security, use encryption (AES, RSA) first, then optionally Base64 encode the encrypted result for transmission.

Understanding Size Increase

Size Overhead: Base64 encoding increases data size by approximately 33% (4/3 ratio). For every 3 bytes of input, Base64 produces 4 bytes of output.

Why the Increase?: Base64 uses 6 bits per character instead of 8 bits per byte. Three 8-bit bytes (24 bits) become four 6-bit Base64 characters (24 bits), but each character needs 8 bits to store, resulting in 32 bits total.

Example: "Hello" (5 bytes) becomes "SGVsbG8=" (8 bytes) - a 60% increase. Larger inputs approach the theoretical 33% overhead.

Pro Tips for Base64

Not for Security: Base64 is encoding, not encryption. Anyone can decode it. Don't use it to "hide" sensitive data.
Check Padding: Valid Base64 strings should have correct padding (= characters at the end). Missing padding may cause decoding errors.
Mind the Size: Base64 increases data size by ~33%. For large files, consider compression before encoding or use binary transfer if possible.
Remove Whitespace: When decoding, remove line breaks, spaces, and other whitespace that may have been added for readability.
Use Data URIs: For small images (<10KB), embed as Base64 data URIs in HTML/CSS to reduce HTTP requests.
URL-Safe Base64: Use Base64URL variant (- instead of +, _ instead of /) for encoding data in URLs to avoid special character issues.
Validate Before Use: Always validate decoded Base64 data, especially if it's user-provided, to prevent injection attacks.
Compress Then Encode: For large text, compress (gzip) first, then Base64 encode for better efficiency.
Use Swap Feature: Quickly switch between encoding and decoding by using the Swap button to exchange input/output.

Common Base64 Applications

HTTP Authentication: Basic HTTP authentication uses Base64 to encode username:password credentials in the Authorization header (though HTTPS should always be used).

JWT Tokens: JSON Web Tokens (JWT) use Base64URL encoding for their header and payload sections, making them URL-safe and readable.

Inline Images: Data URIs with Base64 encoding allow images to be embedded directly in HTML/CSS: data:image/png;base64,iVBORw0KG...

Email Encoding: MIME (Multipurpose Internet Mail Extensions) uses Base64 to encode email attachments and non-ASCII characters in headers.

XML/SOAP: Base64 encoding allows binary data to be included in XML documents and SOAP messages without violating XML syntax rules.

Best Practices

Always Use HTTPS: When transmitting Base64 encoded sensitive data, always use HTTPS/TLS encryption for the transport layer.
Validate Input Length: Set reasonable size limits for Base64 encoding to prevent memory issues with very large inputs.
Handle Errors Gracefully: Implement proper error handling for invalid Base64 strings instead of letting applications crash.
Document Your Usage: Clearly document when and why Base64 is used in your codebase for future maintainers.
Consider Alternatives: For modern web applications, consider using binary protocols (WebSocket, gRPC) instead of Base64 when possible.
Cache Encoded Results: If encoding the same data repeatedly, cache the Base64 result to avoid redundant processing.
Test Edge Cases: Test with empty strings, special characters, Unicode, and very long inputs to ensure robust handling.

Troubleshooting Common Errors

"Invalid character" Error: The input contains characters not in the Base64 alphabet (A-Z, a-z, 0-9, +, /, =). Remove or replace invalid characters.

"Invalid string length" Error: Base64 strings must have a length that's a multiple of 4. Check for missing padding (=) or truncated strings.

Garbled Output: If decoded text looks wrong, ensure the original encoding used UTF-8. Different character encodings can cause issues.

Line Breaks in Base64: Some systems add line breaks for readability. Remove all whitespace (spaces, tabs, newlines) before decoding.

🔒 100% Privacy Guaranteed

All Base64 encoding and decoding is performed entirely in your web browser using JavaScript. Your data is never uploaded to our servers, stored in databases, logged, or transmitted to any third party. Everything happens locally on your device, ensuring complete privacy and security for your sensitive information.

Base64 Encoder & Decoder

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Output

About Base64 Encoding

Complete Guide to Base64 Encoding & Decoding