Start with a square source image

A square PNG source almost always gives the cleanest result. Non-square assets can be forced into ICO output, but that increases the chance of cramped or awkward icons at smaller sizes.

Generate multiple embedded sizes

A good favicon workflow does not stop at one resolution. The ICO file should include 16, 32, 48, 64, 128 and 256 pixel variants so browsers and desktop contexts can choose the best match.

Keep the pipeline simple

For small teams, a manual upload flow is enough. For agencies or product teams updating many sites, batch conversion and API access remove the repetitive part of favicon maintenance.