Dino is a modern open-source chat client for the desktop. It focuses on providing a clean and reliable Jabber/XMPP experience while having your privacy in mind.
You have to register an account to use it, with a username and password and pick a server (you can use public ones or others). But that’s it basically. No ads, no premium features, no data collection, no bullshit. What I really like about them is that they don’t advertise these trade-based networks like facebook and twitter, they only use mastodon. If you’re really strict with all the trades you could argue that the sticker incentive might be bad: “If you donate 5€ or more, we can send you stickers! Include your postal address in the PayPal transaction comment or send it via e-mail to sticker at dino.im.” But that’s the only thing on the website.