Big Tech is evil - I know that, you know that.
I don't know what convinced you - maybe it was the Cambridge Analytica scandal, maybe it's Musk and X being at the epicenter of US election misinformation, or maybe it's just that algorithmic social media leads to radicalization and contributes to increased political violence.
So... we have to do something, right? You're here because we have to do something - and it starts with you and me! We have to leave - and we have to help others leave!
Let's all leave:
Big-tech social media makes money by keeping you engaged, so they can show you ads and profile you and sell your data to third parties. They spend billions developing algorithms which get you addicted.
For the most part, independent social media doesn't do that, which is a good thing, but you will likely find that you have to put in more effort to fill your feed with interesting stuff, or even to get your own content out there and shared.
Because - the algorithm is real people who share content.
Instagram is the worst social media for mental health - which is reason enough to leave - especially for teenagers. It is also owned by Meta Platforms (aka Facebook), which deserves a whole article in itself.
Luckily there's a pretty good drag-n-drop replacement you can use; Pixelfed!

Pixelfed is part of the fediverse which means it has a decentralized architecture - you don't need to know what that means except that when you sign up you need to select a server to sign up to, but all servers can see content from each other.
The main instance is pixelfed.social - but there are plenty of servers to choose from, I personally use pixelfed.dk because it has a primarily Danish user base.
See if you can find a server to your liking here:

WhatsApp & Messenger
WhatsApp and Messenger are the two most prominent instant messaging platforms available globally - with more than 3 billion users. They are both owned by Meta Platforms.
To replace either of these two you can use:
Signal is a simple to use and open source IM-service featuring end-to-end encryption and . It is developed by a non-profit foundation and is available for both Android and iOS as well as Windows, macOS, Linux.

Matrix is an open standard for instant messaging also developed by a non-profit organization. Because it's an open standard, many different apps exist for it - you can choose whichever one suits you and go with that.

Comparing the two, Signal is perhaps a little bit easier to use - but requires you to sign up using a phone number. Matrix is a little bit more techy, but is decentralized and you can run your own server if you're so inclined.
...is not choosing the server and client. It's asking people to install a new app in order to talk to you - but give it a shot!
I was happy to discover that, by now, many people are ready to try new platforms out, especially if you help them get started!
Twitter/X
Twitter is the platform which people have been most vocal about leaving, with Musk being such a giant dickhead, and as such there are several alternatives.
Currently the most popular seems to be bluesky - a pretty much straight up copy of Twitter by some of the people who left Twitter when Musk bought it.

I personally have some reservations about bluesky - I don't like that it has an algorithm which serves you content, I don't like that it's not decentralized in any meaningful sense of the word, and I think they'll soon introduce advertising on the platform - but it has a large and growing userbase, and if you're not concerned about the stuff I am concerned about it may be a great choice.
The other alternative is Mastodon - which has also existed for a while and has a pretty large user base. Like many of the other social media platforms mentioned here it's federated which means you can also follow people on other federated platforms (like Pixelfed!) - and they can follow you.

Mastodon is filled with nerds (like me!), it is unapologetically techy, left wing, and LGBTQ-friendly, and full of all sorts of interesting and weird people.
Bluesky is a lot more mainstream - but most important; both are infinitely better than supporting the fascist oligarky by being on Twitter!
A couple of years ago, Reddit decided to shut down all third-party apps. This pissed off a lot of people, and many people tried to migrate elsewhere - for that and other reasons.
The most popular of the alternatives turned out to be Lemmy - a so-called link aggregator and discussion forum which looks and feels like old reddit.
Like many of the other options mentioned here, lemmy is decentralized and consists of many smaller servers you can sign up to, but which can see and interact with content from each other.
Some of the more popular instances are:
- lemmy.world (general purpose)
- lemmy.ee (general purpose)
- feddit.org (German, european)
- sh.itjust.works (Canadian EN/FR)
- sopuli.xyz (Finnish, general purpose)
I personally use feddit.dk - a primarily Danish-speaking instance - but please remember that no matter where you sign up, chances are you can interact with content and communities from all of the servers above.
On your mobile devices you'll want to use an app to browse lemmy - there are many to choose from, give them a spin and see which one you like the best:
This is just a subsection of apps - you can find more apps here.
YouTube
Youtube is a little difficult to replace - not a lot of ethical and free video services exist, and those that do probably don't have all the content you're used to.
But consider PeerTube - a free and open source alternative to YouTube:

PeerTube is federated - this means that pretty much everyone can install an instance on their own server, and all these instances can communicated with each other and share videos between them. You can find a list of PeerTube instances here.
There aren't really any good alternatives to Facebook - although Friendica could be one with a more tight and modern UI - but you can replace the parts of Facebook you use.
Often this boils down to:
- Groups
- Events
- Marketplace
- Messenger
For groups the replacement depends on the kind of group. If it's a fairly open community centered around a hobby you could consider a lemmy community. If it's a closed group of some sort a matrix or signal group might do the trick.
For events you can consider gath.io or something like mobilizon (also has a group-feature) which is also sharable via ActivityPub (the protocol used by Mastodon, Lemmy, Pixelfed, and more).
For marketplace there are many alternatives, the main draw of Facebook Marketplace is the number of people you can reach. If you're looking for a federated alternative to self-host consider flohmarkt.
For messenger - well, that's covered under WhatsApp & Messenger above.
Final remarks
The main challenge is of course not creating an account somewhere else, the thing that ties us to big tech social media is people and community. And you're never going to be able to convince everyone to move, but... give it a shot, help build an alternative social media landscape for people to join. Keep the lights on, and one day - it will feel like home π