Base64 String Encoder & Decoder

What is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts binary data into a printable ASCII string format. It represents binary data using 64 characters (A-Z, a-z, 0-9, +, /) plus '=' for padding. Base64 encoding is widely used in web development to embed binary content — such as images, fonts, or file attachments — inside text-based formats like JSON, HTML, CSS, and email (MIME). The encoding follows the specification defined in RFC 4648. Because each group of 3 bytes becomes 4 Base64 characters, encoded output is roughly 33% larger than the original data.

How to Use This Free Online Base64 Encoder & Decoder

1. Paste or type the text you want to encode or decode into the input field.
2. Select the mode: Encode (text → Base64) or Decode (Base64 → text).
3. The result appears instantly in the output field — no button click needed.
4. Click the Copy button to copy the result to your clipboard.

Common Use Cases for Base64 Encoding

• Embedding images in HTML or CSS — Convert small images to Base64 data URIs to reduce HTTP requests and inline them directly in your markup or stylesheets.
• Encoding data in JSON APIs — Safely transmit binary payloads (like file content or cryptographic signatures) inside JSON strings without escaping issues.
• Email attachments (MIME) — MIME-encoded emails use Base64 to embed binary attachments inside the text-based email format.
• HTTP Basic Authentication headers — The Authorization header encodes the username:password pair in Base64 before sending it to the server.
• Storing binary data in text-only databases or configs — When a storage system only accepts text, Base64 lets you safely persist binary blobs without corruption.