Open + Vector = awesome!

• Google Noto - the complete set from Android (source).
• Twitter Twemoji - a complete set, licensed CC-BY 4.0 but with easy attribution requirements (source).
• OpenMoji - consistent line-oriented images, including some custom extras. Licensed CC BY-SA-4 (source).
• Mozilla's Firefox OS - very nice, but no longer being updated (source).
• EmojiTwo - a fork of the last open version of EmojiOne. Only a few updates since, but still pretty good source.
• Emojidex aka PhantomOpenEmoji (source).
• Streamline's Kawaii (freemium, only low-res for free) and Freemoji (freemium, attribution required for free use)

Straight from the horse's mouth

• Comparison table - all the emoji except skin-tone variations, with images for each major platform.
• Skin-tone comparison table the emoji missing from the above chart, with images for each major platform.
• Recent additions - list of what's new. Usually not supported on all the platforms yet.
• List - just a single sample image, but with the official name and alternate names/keywords for each emoji.
• Counts - so you know that there are 3,782 distinct emoji (as of June 2023).
• Unicode Technical Standard 51 - all the gory technical details. A bit dry, unless you are a emoji geek (which you definitely are if you have read this far!).

• Emojipedia - great reference site, with images for all the plaforms (including historical), but only png and no links to the sources.
• Wikipedia's Emoji Page - lists all the emoji with sample images from the major open platforms (including historical versions).

• Github API JSON - a json file that maps to a URL of a png image.
• Unicode emoji data files - the raw data, in case you are developing something from scratch.

• EmojiCopy - a decent copy-to-clipboard site.
• Emoji-cheat-sheet - another copy-to-clipboard site, though not updated in 4 years (source).

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