ICO is a image format: it bundles multiple raster images at different resolutions (16x16 through 256x256) into a single file for use as application icons. ET is a document format that stores data in the ET format. This embeds the raster image inside a document container, fixing its dimensions on the page. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. Converting between these two formats is common when the source application does not support ET natively or when the target platform only accepts ET. 1converter processes this conversion server-side using open-source tools. Files are transferred over HTTPS, converted on secure cloud servers, and automatically deleted after 24 hours.