Base64 Encode & Decode - Online Base64 Converter
How to Use the Base64 Encoder and Decoder
Select Encode or Decode mode, paste your text or Base64 string into the input field, and the result appears instantly. Click the copy button to copy the output to your clipboard. The tool handles UTF-8 characters correctly, so international text, emoji, and special characters encode and decode without issues.
What Is Base64 Encoding
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters: A-Z, a-z, 0-9, plus (+), and slash (/), with equals (=) used for padding. It was originally designed for email transmission but is now used throughout web development and APIs.
The encoding process takes every three bytes of input and maps them to four Base64 characters. This means the encoded output is always about 33% larger than the input. Despite this overhead, Base64 remains essential whenever binary data needs to travel through text-only channels.
Common Use Cases for Base64
Base64 encoding appears in many areas of web development and backend systems:
| Use Case | Example |
|---|---|
| Data URIs | Embedding small images directly in CSS or HTML |
| API payloads | Sending binary files in JSON request bodies |
| Email attachments | MIME encoding for email content |
| Authentication | HTTP Basic Auth header credentials |
| JWT tokens | Encoding header and payload sections |
| Configuration | Storing binary data in environment variables |
Encoding Images as Data URIs
One of the most common Base64 use cases is converting small images into data URIs. Instead of loading an image from a separate HTTP request, you can embed the Base64-encoded image directly in your CSS or HTML. This reduces HTTP requests but increases the HTML/CSS file size, so it is best for small icons and logos under 10KB.
Base64 and Web Security
While Base64 is not encryption, it plays a role in several security-related protocols. JWT tokens encode their header and payload sections as Base64 before signing. HTTP Basic Authentication sends credentials as Base64-encoded strings. In both cases, Base64 is used for transport encoding, not protection. Always use HTTPS to protect Base64-encoded credentials in transit.
If you need to inspect JWT tokens that contain Base64 sections, use the JWT Decoder to parse them visually. For actual encryption needs, the Text Encryptor provides AES-256 encryption that runs in your browser.
Working with URL-Safe Base64
Standard Base64 includes the + and / characters, which have special meaning in URLs. When you need to use Base64 strings in URLs or query parameters, you have two options: use URL-safe Base64 (which substitutes - for + and _ for /), or apply URL encoding to the standard Base64 string to escape those characters.
Privacy and Browser-Side Processing
This tool processes everything locally in your browser. No data is sent to any server, making it safe for encoding sensitive information like API keys, tokens, or credentials. The encoding and decoding operations use the browser’s built-in btoa() and atob() functions with proper UTF-8 handling.
Related Tools
- URL Encoder/Decoder - Encode special characters for safe use in URLs
- HTML Entity Encoder - Encode characters for safe HTML display
- JWT Decoder - Decode and inspect Base64-encoded JWT tokens
Frequently Asked Questions
What is Base64 encoding used for?
Base64 encoding converts binary data into ASCII text so it can be safely transmitted through text-based protocols. Common uses include embedding images in HTML/CSS, encoding email attachments (MIME), transmitting binary data in JSON APIs, and storing credentials in HTTP Basic Authentication headers.
Does Base64 encoding encrypt data?
No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string back to its original content without a key. If you need to protect sensitive data, use actual encryption like AES-256 before encoding.
Why does Base64 increase file size?
Base64 represents every 3 bytes of binary data as 4 ASCII characters, resulting in roughly a 33% size increase. This overhead is the tradeoff for being able to transmit binary data through text-only channels like JSON, XML, or email.
Is Base64 safe for URLs?
Standard Base64 uses characters like + and / that have special meaning in URLs. URL-safe Base64 replaces these with - and _ respectively. When embedding Base64 in URLs or query strings, use the URL-safe variant or additionally URL-encode the string.