The five names you will see most are Discourse, Flarum, NodeBB, phpBB, and MyBB. All five are free and open source, and all five are good software. Discourse is the fullest of the group and the heaviest to run. Flarum and NodeBB are lighter and feel more modern. phpBB and MyBB are the long-lived classics, and they run on cheap shared hosting. There is no single best one. The right pick depends on the job your forum has to do, and on who will keep it running after launch.
Here is the detail, one project at a time.
The five names you will keep seeing
Each of these is a real project with real people behind it. Some are run by companies, some by volunteers. All of them have carried large public communities for years.
Discourse
Discourse is a discussion platform made by the company of the same name. It is open source under the GNU GPL, so you can run it on your own server without paying for a license.
It runs on Ruby on Rails, with PostgreSQL as the database and Redis alongside it. The official way to install it uses Docker, which keeps those pieces together in one bundle.
Running it is the heaviest job of the five. It will not sit on a basic shared PHP host. You want a server you control, with enough memory for those services. In return you get a lot in the box, including trust levels that give steady members more ability over time, and email replies that work like a mailing list.
Discourse also sells official hosting for people who would rather not run it. Its pricing page listed plans starting at $100 per month when we checked in September 2026.
Teams tend to pick Discourse when they want a serious public community and have someone who can look after a server.
Flarum
Flarum is forum software written in PHP. It is free and open source, and the core is kept deliberately small. Extensions add the rest, so you choose what your board can do.
The reading experience is one flowing page. Discussions are flat rather than deeply nested, which keeps long threads easy to follow.
To run it you need PHP, a MySQL or MariaDB database, and a web server. Plenty of shared hosts can handle that. It asks for a current version of PHP, and it is usually installed with Composer, a package tool for PHP, so command line access helps.
People tend to pick Flarum when they want a clean, modern-looking community and do not mind adding extensions themselves.
NodeBB
NodeBB is forum software written in JavaScript and run with Node.js on the server. It is open source, and the company behind it also offers managed hosting for anyone who wants it done for them.
It can store its data in MongoDB, PostgreSQL, or Redis. That choice is unusual among forum projects and handy if you already run one of those.
Running it means having a server that can run Node.js and keep a process alive. Most cheap shared hosting cannot do that. Pages update live, so new posts show up without a refresh.
Teams tend to pick NodeBB when they are already comfortable with JavaScript on the server and want a board that feels quick and current.
phpBB
phpBB is one of the oldest forum projects still going, and it is still actively maintained by volunteers. It is free and open source, written in PHP, and it works with common databases such as MySQL.
This is the easy end of the range. It installs on ordinary shared hosting, the kind that costs a few dollars a month. The layout is the classic board: categories, then forums inside them, then topics, then posts in order.
People tend to pick phpBB when they want a familiar public board, cheap hosting, and software with a very long track record.
MyBB
MyBB is another classic PHP board, also free and open source, and also run by volunteers. It covers the same ground as phpBB: categories, forums, threads, and posts, with themes and plugins on top.
Like phpBB, it is happy on shared hosting and simple to install. It has a full admin control panel where most settings live, and a template system you can edit to change how the board looks.
People tend to pick MyBB when they want a straightforward board they can restyle, without much server work.
What actually separates them
Three things matter more than the rest when you are choosing.
The first is weight. Discourse and NodeBB need a real server with services running on it. Flarum, phpBB, and MyBB fit the plain PHP hosting most people already have. That one fact narrows the list faster than any feature comparison.
The second is the shape of the conversation. All five are built for open discussion first, not for questions and answers. There is no built-in idea of one correct reply that sits at the top of the page. Several can be pushed part of the way there with add-ons, but that is something you bolt on, not the core shape of the software.
The third is finding help when you are stuck. Each project runs its own public forum on its own software. That is the best place to ask a question, and it also shows you the software in real use before you commit.
The upkeep is the same job on all five
Self-hosting any of these means the same short list of chores becomes yours. You install updates, including security updates. You take backups, and you test one by restoring it. You keep your email landing in inboxes instead of spam folders. You also handle spam, because a public forum with open sign-up gets found by spammers quickly.
None of it is hard. It is just constant. Say it takes an hour in a normal month, and a slow afternoon when a major update lands. Over a year that is a real amount of someone's time. It has to be someone's job, or it stops happening.
That trade is worth thinking through before you install anything. We walk through the same decision in more detail on the page about forum hosting choices, including when paying someone else to run it is the cheaper answer.
How to choose, by the job you have
If you want an open community with depth, long threads, and strong moderation, Discourse is the natural pick, as long as you can carry the weight of running it.
If you want a lighter modern community and you like choosing your own parts, look at Flarum. If you want the same lightness but your team lives in JavaScript, look at NodeBB.
If you want a familiar board on cheap shared hosting, with almost no server work, phpBB and MyBB both do that well. Install both, look at each admin panel, and pick the one you prefer. You will be the one using it every week.
If you want the direct head-to-head detail, such as Flarum next to Discourse, we keep that on our page comparing open source forum options side by side.
When the job is customer questions and answers
There is one case worth pausing on. If the forum's real job is customers asking about your product and your team answering, a discussion platform may be more than you need. What you want is a question, a clear answer marked as the right one, and a page a search engine can find later. The rest of the discussion features will mostly go unused.
That is the job a customer support forum is shaped for, and it is what we built Forumcat to be. It is hosted, so there is nothing to install and no server to update. A portal is live in about five minutes. It is $9 one time on a Forumcat subdomain, or $99 a month with your own domain, and there is a 7-day free trial with no card.
For customer questions, a smaller tool can carry the whole job.
If your forum is really a community, ignore all of that and install one of the five above. They are built for community discussion, and that is not what Forumcat does.
Keep reading: our roundup of free forum software and a closer look at what Discourse hosting costs.