Overview

Encode text and binary data into Base64 format, or decode Base64 strings back to the original data. Commonly used for email attachments, data URIs, and API communication.

Formula

Base64 encoding process: Group input bytes into 3-byte (24-bit) chunks and split each into four 6-bit groups. Map each 6-bit value (0–63) to the character set A–Z, a–z, 0–9, +, / (64 characters). If the input length is not a multiple of 3, append '=' padding characters. The output size is approximately 4/3 of the original (about 33% larger).

How to Use

1. 1Select encode or decode mode.
2. 2Enter the text or Base64 string.
3. 3The conversion result is displayed automatically.
4. 4Copy the result for use wherever needed.

Tips

• ✔Base64 is encoding, not encryption. Do not use it for security purposes.
• ✔URL-safe Base64 uses '-' instead of '+' and '_' instead of '/'.
• ✔When using in a Data URI, prepend 'data:image/png;base64,' as a prefix.
• ✔You can estimate the original size from the encoded string length: original ≈ Base64 length × 3/4.

FAQ