Why?
When you use WhatsApp, you're not just sending messages, you're building your relationships and daily life inside a system owned by Meta Platforms and led by Mark Zuckerberg. The messages may be encrypted, but the map of your life - who you talk to, when, and from where - still lives there. And when the same company is actively building ties with people in power like Donald Trump, it's a reminder that this isn't neutral infrastructure - it's a privately owned space shaped by business interests and political relationships. Matrix/Element is an alternative: communication that works more like the internet itself - open, shared, and not owned by any single company.
How?
The sneaky trick that these tech oligarchs have pulled, of course, is that they have already captured the market. Most of your friends and family may already be on this rotten system! So if YOU set up an account on this other new "radical tech-hippy" system (Matrix/Element), who are you going to talk to? Well, just like when you first set up WhatsApp or told your friends about it, let's do it one more time - it's not that hard, and there's a very good reason to do so, which you can link to above when you send your friends a link to Element.io. And also, it doesn't have to be all-or-nothing, at first - you may have already set up accounts on a bunch of other tech oligarch platforms (like Facebook, Instagram, FaceTime, etc). So ease into it - add Element/Matrix and start having a few chats with like-minded friends who are sick of information tracking and the tech oligarch bros in bed with Trump.
Why?
The proprietary social networking services are the next biggest take-over of basic human communication tools, after simple messaging (like WhatsApp). And, again, they are all either property of The Zuck, or Elon Musk, or other such tech bros. Even small local businesses and organizations use them to provide links for our neighbors and friends to "follow" their activity. So to do so, you need to create an account and, even worse than WhatsApp, you not only expose your social networks and location information, but you also expose comments and communications. And let's say there is important information for my neighborhood, like a criminal on the loose, or a community event, or a favorite restaurant that you are waiting to be reopend - only people who have signed up for these platforms get that information, and all of that valuable social information is not only sucked up for free for marketing, it is also made available for government surveillance.
How?
Most folks seeking to get away from Facebook and Twitter/X will probably be most comfortable with Friendica. Unlike the proprietery and centralized services, you can sign up for Friendica anywhere! You can go to a major server like friendica.world, but in the spirit of decentralization, I encourage you to open an account on friendica.opensourceit.org. The interface may feel a bit foreign and require some getting used to - but I'm sure it's no different from when you first signed up for Facebook (if you can remember that far!).
For Instagram, there is Pixelfed, and major servers like pixelfed.social (I don't have my own server up - yet!).
Absolute garbage. Talk about two people who gave no shits about open communication and just said "sign up for our service, share your personal information, and only those on our service will ever be able to share in these experiences - even though it's the most basic thing ever". Look at these assholes. They're so happy they made bank off of their pet rock. I'll be posting a guide for how to set it up yourself soon.
People go to Nextdoor because they want to connect with their local community. And that's great! Nextdoor is generally awful in the same way as Facebook and and other ad-mongers. It's awful because the users who just want to connect and share with their neighbors are sucked into an ad platform which then winds up promoting larger businesses who can afford $1000/mo advertising costs for this ONE channel for ONE neighborhood. It is again an example of non-innovative tech which provides zero technical value while corralling communities and creating artifical value for themselves and larger companies, while diminishing the voices of smaller businesses.
So what's the alternative? Subscribing to local community blogs is a time-honored tradition since the 90's and there are still many good ones out there - but in the social networking age they can seem a bit limited, and they are. So the obvious alternative is focused social network tagging on open platforms. Just subscribe to #sacramento or #west-seattle or whatever your neighborhood interest is. That provides you the same feed view that you get on a Nextcloud neighborhood subscription. And if you start getting spammed by annoying advertisers, then block them! That way businesses are incentivized to advertise appropriately and local users can choose to lift up local businesses for nearly zero cost! And the cost is extremely marginal - all you need is a few federated social networking hubs (like mastodon.social or friendi.ca) to form a healthy network. Local governments could provide this for a paltry sum, but even simple users like you and me can afford to support it for ones of dollars a month. See my guides (coming soon!) on setting up your own social networking instances if you're interested in a little side-project, or just join one of the many out there.