Base64 Encoder & Decoder

Encode and decode text using Base64 encoding

Input Text

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Secure

All encoding/decoding happens in your browser. No data sent to servers.

Fast

Instant encoding and decoding with no delays or processing time.

Unlimited

Encode and decode as much text as you need, completely free.

Complete Guide to Base64 Encoding & Decoding

Base64 encoding is a fundamental technique for converting binary data into ASCII text format, making it safe for transmission over text-based protocols. Our free Base64 encoder and decoder tool handles text, images, and files instantly, providing bidirectional conversion with complete privacy.

What is Base64 Encoding?

Base64 is an encoding scheme that converts binary data (bytes) into a text string using 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). This encoding makes binary data safe for systems that only handle text, such as email, JSON, XML, URLs, and data URIs.

Our Base64 converter transforms any data into a format that can be safely transmitted through text-only channels without corruption. The encoding increases data size by approximately 33% but ensures compatibility across all systems.

How Does Base64 Encoding Work?

The Base64 algorithm follows these steps:

  1. Binary Conversion: Input data (text, image, file) is converted to binary representation (bits).
  2. Group into 6-bit Chunks: Binary data is divided into 6-bit groups (2^6 = 64 possible values).
  3. Map to Characters: Each 6-bit group maps to one of 64 ASCII characters in the Base64 alphabet.
  4. Add Padding: If needed, padding characters (=) are added to make the output length a multiple of 4.

Example: The text "Hello" encodes to "SGVsbG8=" in Base64. Our online Base64 encoder performs this conversion instantly.

Common Use Cases for Base64

Our Base64 encoding tool serves numerous practical applications:

  • Email Attachments: MIME email encoding uses Base64 to send files and images through text-only email protocols (SMTP).
  • Data URIs: Embed images directly in HTML/CSS using data:image/png;base64,... URIs. Reduces HTTP requests and improves page load for small images.
  • JSON & XML: Include binary data (images, PDFs, files) in JSON API responses or XML documents.
  • Authentication: HTTP Basic Authentication transmits credentials as Base64-encoded username:password strings.
  • Cryptographic Keys: Store and transmit encryption keys, certificates, and signatures in text-safe format.
  • URL Parameters: Pass binary data through URL query strings safely (with URL-safe Base64 variant).
  • Database Storage: Store binary blobs in text-based database fields or configuration files.
  • File Transmission: Send binary files through text-only APIs or webhooks.

Text Encoding & Decoding

Use our tool to encode or decode text data:

Encoding Text: Convert any text (ASCII, Unicode, UTF-8) to Base64. Useful for obfuscating configuration values, passing text through systems with character restrictions, or embedding text in data URIs. Example: "Hello World" becomes "SGVsbG8gV29ybGQ=".

Decoding Text: Convert Base64 strings back to original text. Essential for reading encoded data from APIs, decoding email content, or extracting embedded text. Our Base64 decoder handles all valid Base64 input automatically.

Image & File Encoding

Our tool supports encoding images and files to Base64:

Image Encoding: Upload JPG, PNG, GIF, SVG, or any image format to get Base64-encoded output. Perfect for creating data URIs for CSS backgrounds, HTML img tags, or embedding images in JSON/XML. Output includes proper MIME type prefix: data:image/png;base64,iVBORw0KG...

File Encoding: Encode any file type (PDF, ZIP, documents, executables) to Base64 for transmission through text-based systems. Useful for API integrations, webhooks, or storing files in databases.

File Decoding: Convert Base64 strings back to downloadable files. Upload Base64 text to retrieve the original file. Handles any file type automatically.

Data URIs for Web Development

One of the most popular uses of Base64 is creating data URIs for web development:

What are Data URIs? Data URIs embed file content directly in HTML or CSS using the format: data:[MIME-type];base64,[encoded-data]. This eliminates separate HTTP requests for small assets.

Benefits: Reduced HTTP requests, faster page loads for small images, better performance on high-latency connections, embedded favicons, inline SVG icons.

Best Practices: Use for small images (< 10KB), avoid for large files (increases HTML/CSS size), combine with CSS sprites for multiple small images, works best for images that rarely change.

Example usage in HTML: <img src="data:image/png;base64,iVBORw0KG...">

Base64 vs Base64URL Encoding

There are two Base64 variants with different character sets:

Standard Base64: Uses characters A-Z, a-z, 0-9, +, and / with = padding. This is the default and most common variant. Used in email (MIME), data URIs, authentication, and general encoding.

Base64URL (URL-Safe): Replaces + with - and / with _ to avoid issues in URLs. Removes = padding to prevent conflicts with URL encoding. Used in JWT tokens, URL parameters, file names, and OAuth tokens.

Our Base64 encoder online supports both standard and URL-safe Base64 encoding. Simply check the "URL-Safe Base64" option when encoding text to get URL-compatible output. You can also optionally remove padding (=) characters for even more URL-friendly results.

Batch File Encoding

Need to encode multiple files at once? Our batch encoding feature allows you to:

  • Upload Multiple Files: Select or drag-and-drop multiple files simultaneously for encoding.
  • File Type Detection: Automatically identifies file types with color-coded icons (images, PDFs, documents, archives, code files, etc.).
  • Individual Previews: See image previews for all encoded image files.
  • Easy Management: Copy or download Base64 output for each file individually.
  • Time Saving: Encode dozens of files in seconds instead of one-by-one.

Perfect for developers working with multiple assets, preparing image galleries, or batch processing files for API uploads.

Understanding Base64 Output Size

Base64 encoding increases data size:

  • Size Increase: Base64-encoded data is approximately 33% larger than the original. Every 3 bytes of input becomes 4 characters of output.
  • Example Calculation: A 10KB image becomes ~13.3KB when Base64-encoded. A 100KB file becomes ~133KB.
  • Why the Increase? Converting 8-bit bytes to 6-bit characters requires more characters to represent the same data.
  • Considerations: For large files, Base64 can significantly increase transfer size and bandwidth usage. Consider binary transfer methods for large files.

Base64 in APIs & Web Services

Base64 is extensively used in modern web APIs:

  • RESTful APIs: Include file uploads or binary data in JSON request/response bodies.
  • GraphQL: Upload files through GraphQL mutations using Base64-encoded strings.
  • Webhooks: Send file attachments or images through webhook payloads.
  • Authentication: HTTP Basic Auth, API keys, and tokens often use Base64 encoding.
  • OAuth & JWT: JSON Web Tokens use Base64URL encoding for header and payload.

Common Base64 Errors & Solutions

Troubleshoot Base64 encoding/decoding issues:

  • Invalid Character Error: Base64 strings should only contain A-Z, a-z, 0-9, +, /, and =. Check for extra spaces, newlines, or invalid characters.
  • Length Issues: Valid Base64 strings have lengths that are multiples of 4. If not, padding (=) may be missing.
  • Corrupted Output: Ensure proper character encoding (UTF-8) when encoding/decoding text. Line breaks in Base64 strings can cause issues - remove them.
  • MIME Type Errors: When creating data URIs, ensure correct MIME type (image/png, image/jpeg, application/pdf, etc.).

Security Considerations

Important security aspects of Base64:

  • Not Encryption: Base64 is encoding, not encryption. Anyone can decode Base64 strings. Never use Base64 alone to protect sensitive data.
  • Obfuscation Only: Provides minimal obfuscation. Don't rely on it for security. Combine with proper encryption (AES, RSA) for sensitive data.
  • Data Exposure: Base64-encoded credentials in URLs or logs can be easily decoded. Use secure transmission (HTTPS) and proper encryption.
  • Injection Attacks: Validate and sanitize Base64 input before decoding to prevent injection attacks or malformed data.

Browser-Based Privacy

Our Base64 encoder and decoder ensures complete privacy:

  • Local Processing: All encoding and decoding happens in your browser using JavaScript. Your data never leaves your device.
  • No Uploads: Files and images are processed locally. Nothing is transmitted to our servers.
  • Privacy Guaranteed: Encode sensitive documents, credentials, or proprietary data without privacy concerns.
  • Offline Capable: After loading, the tool works offline. Encode/decode without internet connection.

Programming with Base64

Base64 is supported across all programming languages:

JavaScript: Use btoa() for encoding and atob() for decoding. For Node.js: Buffer.from(data).toString('base64') and Buffer.from(base64, 'base64').toString().

Python: import base64; base64.b64encode(data) and base64.b64decode(encoded_data)

PHP: base64_encode($data) and base64_decode($encoded_data)

Java: Base64.getEncoder().encodeToString(data) and Base64.getDecoder().decode(encoded)

Start Encoding Today

Whether you need to encode images for data URIs, transmit files through JSON APIs, decode email attachments, or handle binary data in text-based systems, our free Base64 encoder and decoder provides instant, secure conversion with complete privacy. No registration, no file uploads to servers, unlimited usage. Encode and decode text, images, and files now to streamline your development workflow and handle binary data efficiently.