Convert ico to heif
A browser can't do this one — here is what it can do.
Desktop app only
Nothing that runs in a tab can write heif from ico. This pair is waiting on the desktop build, which hands the job to the real command-line tools.
Browse what does workAbout ICO
Windows Icon
The Windows icon format, which packs several sizes of the same image, such as 16x16 and 32x32 pixels, into one file. Each size is stored as a bitmap or a PNG. Convert to ICO to make a favicon or a Windows application icon.
About HEIF
High Efficiency Image File Format
An MPEG container standard (ISO/IEC 23008-12) from 2015 for single images and image sequences. It can hold HEVC, AV1 or other codecs, along with depth maps and bursts. Convert HEIF to JPG or PNG for apps and sites that cannot read it.