At its core, Nostr is a protocol for broadcasting text across the internet. There are native concepts built into Nostr that lend it well to being a social network, but many popular apps and websites could be rebuild rebuilt on top of Nostr. So what SHOULD be built on Nostr?
I think the answer boils down to: social applications that will benefit from decentralization.
Why Decentralization Matters
Decentralized applications are inherently slower, more expensive, and have their own challenges; but there comes a point where decentralization's costs are outweighed by their benefits.
I wrote about this in more detail in a separate post, but in summary:
Decentralization doesn't help in every situation but it helps reduce abuses of power by spreading power into more hands, forcing consensus, and adding resilience to the system.
With the right technologies and seeded by a community of people who want to improve something, a decentralized version of a product can become more compelling (and therefore displace) the existing offering.
Apps that will thrive on Nostr
These are some of the applications that benefit from decentralization and will thrive on Nostr.
From the time of wax seals on letters to end to end encrypted messaging people have demanded privacy and security from their communications. Right now we have some secure solutions like Telegram and Signal but they're run by companies which can be coerced. Telegram will give information about you to law enforcement when asked (source).
Comms are end to end encrypted by default with Nostr, and so no actor on the network (other than the two people communicating) can share the content of your messages with authorities.
People will have the choice of where their communications are stored and transferred, which is very difficult now, even with the most security-minded products.
People are forced into seeing a feed that best aligns with maximizing the ad revenue of the company, not with the goals of the user. There is no way to opt into a different algorithm for curating your feed.
On top of that the moderation regime of every social media company is monolithic: you can either submit to their rules or not use the app. There is no way to opt into a different moderation strategy.
With Nostr you can choose your content moderation scheme and your feed's algorithm by choosing which relays and which clients you use. Switching clients takes seconds and you bring everything you, instead of now where you bring nothing and start over. (a reminder of how Nostr clients and relays work)
Journalism and publishing
A free press has always been integral to a free society. Having media centralized into a few major companies (source), owned and/or run by a few powerful people, is a tempting recipe for a deep relationship between government and the media. It all leads to a profound lack of accountability.
Podcasting has given the world a taste of the having a more decentralized source of news and information. (source)
Nostr can have a similar effect by allowing controversial media to remain available no matter the opinions of powerful people; and people will be able to choose what sources they consume instead of having their choices artificially limited.
Unsavory things that will thrive on Nostr
Every good system can be used for purposes it wasn't intended for, Nostr will be no different.
Whether you support the usage of Nostr for these purposes or not, it's good to recognize these will be the arguments people will have against Nostr being a force for good in the world.
I was using Nostr the day the porn bots started spamming the global channel on Damus, the popular Nostr iOS app. It was inevitable, and everyone using Nostr lauded it as a milestone for the maturity of the system! Porn is an immutable reality of the internet, and every internet social network will have to decide how it deals with porn.
All of the privacy, security, and lack of censorship that's good for everyday people will also be useful for criminals.
Drug traffickers, human traffickers, terrorists, pedophiles always flock to whatever system will enable them to operate using the easiest tool with the least risk to them.
Combatting bad usage
Usage of Nostr for unsavory activities is a risk that can and will be mitigated to protect people.
Shared and subscribable block lists
Immediately after the porn bots started spamming the Nostr network, relay providers banded together to generate a list of accounts and IPs that were the source of the porn spam.
We can implement something similar to how email reputation works to help people (and clients) decide how to filter out unwanted content.
Choice in algorithm
A robust market of Nostr clients will give users a choice of the algorithm that curates their feed. That way if a user wants to use Nostr for porn, they can do that. If another user wants all porn and violence removed, they can do that too.
Relays setting rules for who can use their services.
Relays can set rules for what content is allowed on their relay. They may do this to comply with the laws for their jurisdiction, or just because that's the kind of business they want to run. But users will be able to choose relays that agree with their sensibilities.
Nostr clients (apps) designed for children
These clients would be designed to filter out content that isn't safe for children. I'm sure a decentralized model for certifying content will emerge to help children access content that's age appropriate (according to their parents not a media company).
Nostr is a powerful, robust protocol that can be used for many things; it will be best suited for use cases where power imbalances cause real harm to people.
Social media that helps people stay informed, journalism that can't be censored, communications that can't intruded upon by authoritarian governments will all be use cases that will be served well by products built on Nostr.
There will be bad actors, but on balance Nostr will enable more good than bad. Besides, all the bad items can be addressed over time. People have been saying that social media was one of the great evils created by the internet; Nostr is proof that we can innovate our way out of problems we discover along the way.