Are these Discord stickers or emoji?

Emoji. The Discord download is sized for custom emoji.

How many emoji can my server hold?

That depends on the server and its boost level; Discord shows the free slots on the Emoji page.

Any pet or animal with a clear face. Pets and other animals only: photos of people, including yourself, are not accepted.

Discord emoji maker for your pet

One photo of your pet becomes 16 stickers, each a different expression: happy, angry, thinking, facepalm and more. The Discord ZIP holds emoji in the format Discord asks for: 128 × 128 px PNG under 256 KB, emoji names of 2 to 32 letters, digits or underscores.

A chibi sticker of a black long-haired cat doing a facepalm, captioned FACEPALM — A real example: the facepalm sticker of a black cat, chibi style.

Upload in Server Settings

On a server where you can manage emoji, open Server Settings, then Emoji, then Upload Emoji, and pick the files. The names are already valid emoji names.

A whole set of reactions

Happy, LOL, angry, sad, love, good night, OK, hmm, wow, hi, thank you, yum, sorry, yay, shy and facepalm: reactions your server will actually use.

Step by step

Upload one photo of your pet. A clear, well-lit photo of one animal with its face visible. JPEG, PNG or WebP still photos. Videos cannot be uploaded. Pets and other animals only: photos of people, including yourself, are not accepted.
Pick a style and see the free preview. Choose Chibi, Kawaii or 3D toy. You get a watermarked preview of the whole sheet first (3 free watermarked previews a day).
Pay once and download. Pay as a guest, no account: $5.99 for a single pack (16 stickers, one style) or $12.99 for the style bundle (48 stickers, all three styles). The HD pack with transparent backgrounds is ready in a few minutes.