Answers
Is Discord safe for kids?
Discord is not designed for children: its terms require users to be at least 13 in most countries (older in some), and its safety depends heavily on which servers a child joins and how their settings are configured. For 13- to 15-year-olds it can be reasonably safe with privacy settings locked down and a parent involved; for under-13s it is against Discord's own rules.
Discord started as voice chat for gamers and grew into a place where almost any interest has a server. That is its strength and its risk: a child can move in a few taps from a moderated school study server to a large public one where strangers can message them, and what they see depends on volunteer moderators in each server rather than on Discord itself.
Age by age. Under 13, Discord's terms do not allow an account at all, and an account found to belong to a child under 13 can be removed. At 13 and 14, the biggest risks are unsolicited direct messages from strangers who share a server, and large public servers with adult content behind thin age gates. At 15 to 17 the practical question shifts from whether to use it to how: most teenagers who use Discord use it to talk to friends they already know, which is the safest way to use it.
The settings that matter most. Under Privacy & Safety, turn off direct messages from server members, so only accepted friends can message. Set who can send friend requests to friends of friends only. Keep the filter for sensitive or explicit media switched on for all direct messages. Leave age-restricted channels off; Discord marks some channels 18+, but the check is only as good as the age the account claims. Discord also offers a Family Center, where a parent can see which servers a teen joins and who they message, but not the content of those messages.
What Discord does not do. Text messages are not end-to-end encrypted, and Discord scans for some illegal content, but it does not screen ordinary messages between people before they are delivered. Moderation in a server is up to that server's owners. Voice chat, where much of the time on Discord is spent, is not moderated in real time at all.
If you are choosing a place for a younger teenager to talk to classmates, look for a service where nobody can find them by name, where messages come only from people they already know, and where a parent is part of the setup. Naven is built on those lines: there is no public directory, a new conversation arrives as a request the child can decline, every message is screened before it is sent, and anybody under 18 needs a parent or guardian to agree. It is not a gaming platform and has no public voice servers, which is exactly what makes it narrower and calmer than Discord.
Whatever you choose, the most protective thing is still a conversation: which servers they are in, who they talk to, and what to do if somebody they do not know sends them something that makes them uncomfortable.