Base64 Encoder/Decoder

Base64 Encoder/Decoder

Encode text to Base64 or decode Base64 strings back to plain text — supports Unicode, files, and URL-safe variants.

What is a Base64 Encoder/Decoder?

A Base64 Encoder/Decoder is an online tool that converts text, binary data, and files between their original form and Base64-encoded format. Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). It is widely used in email attachments (MIME), embedding images in HTML and CSS via data URIs, storing complex data in JSON and XML, API authentication tokens, and encoding data for URL-safe transmission. This tool supports standard Base64 (RFC 4648), URL-safe Base64, and MIME format with line breaks. It handles full Unicode text including emojis, accented characters, and CJK scripts. Designed for developers, system administrators, data analysts, and anyone who needs to quickly encode or decode Base64 strings directly in the browser with zero data sent to any server.

How to Use the Base64 Encoder/Decoder

1. Select your mode — Click "Encode" to convert text to Base64, or "Decode" to convert Base64 back to readable text.
2. Choose options — Select the Base64 variant (Standard, URL-Safe, or MIME), character encoding (UTF-8 or ASCII), and toggle options like line breaks or real-time processing.
3. Enter your input — Type, paste, or use the Paste button to add your text or Base64 string. You can also upload a file (up to 5MB) to encode.
4. Process — With real-time mode enabled, results appear instantly as you type. Otherwise click the Encode/Decode button.
5. Use the output — Copy the result with one click, download as a .txt file, or use the Swap button to reverse the operation.
6. Generate Data URIs — Expand the Data URI section to create embeddable data URIs from your Base64 output, with live image preview for image files.

Features

• Dual mode operation — Switch seamlessly between encoding and decoding with a single click toggle.
• Multiple Base64 variants — Supports Standard (RFC 4648), URL-Safe (using - and _ instead of + and /), and MIME format with 76-character line breaks.
• Full Unicode support — Correctly handles UTF-8 encoding for emojis, accented characters, CJK scripts, and all international text.
• File encoding — Upload any file up to 5MB to instantly encode it to Base64, perfect for embedding images and documents.
• Data URI generator — Built-in data URI creator with MIME type selection and live image preview for encoded images.
• Swap functionality — One-click swap button moves output to input and switches mode, enabling rapid encode-decode verification.
• Real-time processing — Debounced real-time conversion as you type with intelligent delay scaling for large inputs.
• Detailed statistics — Shows input size, output size, size change ratio, processing time, and line count for every operation.

Use Cases

• Web developers — Embed images, fonts, and small files directly in HTML and CSS using Base64 data URIs to reduce HTTP requests.
• API developers — Encode and decode API authentication tokens, Basic Auth headers, and JWT payload sections.
• Email and MIME — Encode binary attachments for email systems that require MIME Base64 format with proper line wrapping.
• Data storage — Encode binary data for safe storage in JSON, XML, databases, and configuration files that only support text.
• Debugging — Quickly decode Base64 strings found in logs, tokens, cookies, and encoded parameters to inspect their contents.
• URL-safe encoding — Generate URL-safe Base64 strings for use in URLs, filenames, and query parameters without encoding issues.

Frequently Asked Questions

What is Base64 encoding?

Base64 is a method of encoding binary data into printable ASCII text using a set of 64 characters (A-Z, a-z, 0-9, +, /). It converts every 3 bytes of input into 4 Base64 characters, making the output approximately 33% larger than the original. It is used whenever binary data needs to be transmitted or stored in text-only systems like email, JSON, or URLs.

Is Base64 encoding the same as encryption?

No. Base64 is an encoding scheme, not encryption. It does not provide any security or data protection. Anyone can decode a Base64 string back to its original form without any key or password. Never use Base64 to protect sensitive information — use proper encryption methods like AES or RSA instead.

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

Standard Base64 uses + and / characters, which have special meanings in URLs. URL-safe Base64 replaces these with - (hyphen) and _ (underscore) respectively, and often omits the = padding characters. This makes the output safe for use in URLs, query parameters, filenames, and cookies without requiring additional URL encoding.

Can Base64 encode images and files?

Yes. Any file — images, PDFs, audio, documents — can be Base64 encoded. This is commonly used to embed images directly in HTML using data URIs (e.g., data:image/png;base64,...), eliminating the need for separate image file requests. Our tool supports file uploads up to 5MB and includes a built-in data URI generator with image preview.

Why does Base64 encoded text become larger?

Base64 encoding increases data size by approximately 33% because it converts every 3 bytes (24 bits) of input into 4 characters (32 bits) of output. This overhead is the trade-off for being able to safely represent binary data in text-based systems. The MIME variant adds additional overhead with line break characters every 76 characters.