PNG ICO ICNS SVG MORE
UI
Outline
Linecon
tick, success, yes
Black
512x512
Glyph
iOS Tab Bar
complete, done, Circle
ok, Circle, done
Google Material Design icons
done, Cloud
done
All, done
ikooni outline: Free Basic
checkmark, Check, complete
Very Basic. Android L (Lollipop)
done, check mark, good
PNG ICO ICNS MORE
Pixel
Gnome icons
followup, for, flag
48x48