Check Mark Emoji Favicon — Free, Fast & Private
The green check button is the completion signal of the whole web: tasks done, forms validated, statuses passing. It is a white tick inside a filled green square, and the filled square is what makes it work, because it supplies an outer boundary a bare tick never has. Its problem is that operating systems already use near-identical marks in their own interfaces.
A to-do app, a status page, a compliance checklist, or an identity verification service. It misleads by implying you are the thing being verified rather than the thing doing the verifying, which matters on review and certification sites. It also collides conceptually with browser and OS security indicators, so on a page about trust or safety it can read as a system-level assurance you are not in a position to make.
Check Mark in a crowded tab strip
Green is scarce among favicons, so this reacquires easily, but it collides hard with anything else green and square: the various green square and green circle glyphs, and every other site that made the same choice. Because the tick is white on green rather than green on white, it survives the dark-tab treatment better than most.
What check mark looks like at 16 pixels
Beside a page title the outer rounded square is doing nearly all the work. At 16 pixels the white tick thins to a hairline and can vanish entirely on a low-DPI display, leaving a green rounded block. That block still reads as approval, because green plus square is enough context. It is a rare case of an emoji surviving on colour alone. The filled green square does the work at 16 pixels; the white tick thins out but the block of green still reads as approval.
Where vendors disagree about check mark
Vendor designs differ mostly in corner radius and in whether the green is flat or gradient. Apple uses a noticeably rounder square with a gradient; Noto is flatter and squarer. Tick weight varies too, and the thin-tick designs are the ones that lose the tick entirely at 16 pixels, so which platform you generate on decides whether your icon has a visible tick at all.
Where the glyph itself comes from
Your check mark icon is drawn on your device by your own colour emoji font, so it matches your platform rather than being a consistent cross-platform design. MiniPx ships no emoji artwork. Emoji are colour glyphs, so the .ico carries colour PNG payloads with alpha.