what about an actually free alternative, like matrix + element?

I haven't tried any of the following, just my 0.02.

Idea0: is there any way to install your instance without using the setup wizard ?

Idea 1: installing and older version (below 6.x) and upgrading it to current version ?

The official documentation page about registration states:

When deploying a self managed Rocket.chat >=6.x workspace you are automatically required to register your workspace upon completing the Setup Wizard

According to the same page, for versions below 6.x you have to manually register your instance.

Idea 2: I noticed a few references to air-gapped installations, and I guess they can't be connected to anything from Rocket.chat HQ. Could Iistalling your server as air-gapped and completing a bogus registration work ?

Official documentation page about Air-gapped installs registration

Hope any of this helps. I'm quire surprised (and not in a good way) to see this mandatory requirement from Rocket.chat. Even if kt means functionality loss (access to their push notif framework for example) you should be able to decline it.

Not an answer, just a warning: This is par for the course when it comes to Rocketchat, every major version seems to come with another piece of nagware, another limit, another thing paywalled. I run a server for the non-profit I work for and they haven't even replied to my mails about maybe offering a more affordable licensing tier before Enterprise.

We don't need a lot, just push notifications (which they have to pay for, so absolutely fair to limit) and LDAP integration that isn't intentionally gimped. A supporter tier with no real extra features (we don't need their customer-facing-type features) and very limited tech support would be really nice, but I guess they don't want our poor people money. Gotta try just really hard to squeeze something from that stone instead.

Example: First they removed automatic LDAP syncing, then they blocked people from still doing it with cron. You now have to enter your admin password every time to sync "for security reasons" unless you pay at least $10 per user and month or something ridiculous (for a non-profit) like that. Not that you'd know from their website, they've removed all pricing information from there.

They've also limited the amount of (free, third-party) add-ons you can install while also adding a new feature that lets users see and request add-ons from admins. So many dark patterns.

Rocketchat narrowly won out over Matrix when Covid started but it sure as hell wouldn't now.

Yes, it's possible but this is not documented anywhere official from what I could tell

I found the following in a github issue comment chain: Assuming you have a container based deployment (which if you don't have, you should probably get), you can set the environment variable OVERWRITE_SETTING_Show_Setup_Wizard=completed to skip the registration. As far as I can tell this still works with the current rocketchat versions. A small additional complexity is that you then can't create your first admin user. This can be fixed by also setting other environment variables which create an administrator if no other admins are found on start:

    OVERWRITE_SETTING_Show_Setup_Wizard=completed
    ADMIN_USERNAME=example
    ADMIN_PASS=example
    ADMIN_EMAIL=example@localhost
    INITAL_USER=yes

The alternative is to register a user and then do some raw database manipulation as documented here and promote the new user; for this you need the mongosh shell in the mongodb container (i. e. something like docker exec -it mongodb mongosh):

use rocketchat                                                                  // switch to rocketchat db

db.getCollection('users').find()                                                // list users
db.users.update({username: "test"}, { $push: { roles: "admin"}})       // make user admin
db.users.update({username: "test"}, { $pull: { roles: "admin"}})       // remove admin role from user

As another user mentioned, the alternative is to deploy older versions and then upgrade. Old container images are available under registry.rocket.chat/rocketchat/rocket.chat:$ver. Versions as recent as 4.4.0 still allow setup without cloud registration. You just need to be a bit careful in the upgrade, as you need to do several smaller steps to reach the current version, so from 4.4.0 to the most recent 6.x would for example be:

4.4.0 -> latest 4.x -> 5.0 -> latest 5.x -> 6.0 -> latest version

(make backups of your db though with mongodump)

In my opinion, rocketchat has an easier deployment compared to matrix (only two containers, three if counting the reverse proxy), but the recent pushiness of the company with their paid services (the seemingly disabled registration, giant advertisements in the settings and most recently the forced depreciation of older instances for their official apps among other things) really makes me question whether that somewhat decreased complexity makes it worth investing time and effort into such a product.

I ran mine without registration. Can't remember if that changed the functionality at all.