Base64 to ICO conversion is the process of decoding a Base64 encoded text string back into its original ICO (Icon) image format. ICO is the standard file format for favicons - the small icons displayed in browser tabs, bookmarks, and address bars - as well as desktop application icons on Windows.

The Base64 decoding scheme reverses the encoding process, converting the 64-character alphabet back into the original binary data. ICO files are unique because they can contain multiple icon sizes within a single file (16x16, 32x32, 48x48, and 256x256 pixels), making them versatile for different display contexts. Unlike server-based solutions, our tool performs all conversions locally in your browser using the atob() API, ensuring your images remain private and secure.

When you decode a Base64 string to ICO, the browser's native atob() function first converts the Base64 text back into binary data. This binary data is then processed as a Blob object and rendered as an ICO image using a data URL or object URL.

The resulting ICO file maintains all of its original properties including multiple embedded icon sizes, color depths, transparency (alpha channel), and metadata. This technique is commonly used when extracting favicons from JSON APIs, recovering icons from databases that store them as Base64, or converting inline favicon data from HTML documents.

While Base64 encoding increases data size by approximately 33%, decoding restores the original file size. The decoded ICO is identical to the original icon file before encoding, with all embedded sizes and quality intact. The process is instant and happens entirely in your browser following web security best practices.