AV1 Image File Format (AVIF) applies AV1 intra-frame compression delivering 50% smaller files than JPEG at equivalent quality, with wide colour gamut support. Windows Icon (ICO) bundles multiple raster images at different resolutions (16x16 through 256x256) into a single file for use as application icons. This conversion changes the file's encoding, compression method, and supported feature set. Colour profiles and orientation metadata are preserved in the output. The result is a standard ICO file readable by any compatible application. 1converter handles AVIF-to-ICO conversion server-side: files are uploaded over HTTPS, processed on isolated cloud infrastructure, and the converted output is available for download for 24 hours before automatic deletion. No account is required for standard conversions.