There are certain restrictions when uploading an emoji to Discord. For one, it must be in JPEG, PNG, or GIF format. It also can't exceed 256KB in size and 128 x 128 in resolution.

If you want more emoji slots, you'll need to have users with Discord Nitro accounts on the server to "boost'' the available slots. If enough users boost your server, you can add up to 250 custom ...

No, all I need is my adorable cat emojis when sending DMs to my pals. Thankfully, for people like me who only need that from a Nitro subscription, Discord is now offering a cheaper tier.