The question is not which platform is nicest to use
Every platform comparison we see is written for joiners: which one feels good, which one has nice threads, which one your audience already has installed. Those things matter for about three months. The decisions that actually bite an owner show up in year two, when you want new people to find the community without paying for them, when a member asks a question that was already answered eleven times, or when your costs start scaling with your success.
We maintain a hand-checked directory of 200 communities for people working in AI, software, data, no-code, SaaS, startups and growth. For each listing we record the platform, member count, activity level, pricing and joining rules. That gives us a useful vantage point: we can see which kinds of communities end up on which platforms, and which constraints they run into once the marketing page is behind them.
Six criteria that decide this, and one table
Below is how the main options compare on the things that get expensive to change later. Prices and limits are from each vendor’s own pages, linked in the sections that follow.
| Criteria | Discord | Slack | Skool | Facebook Groups | Hosted forum | |
|---|---|---|---|---|---|---|
| Found by non-members | In-app Discovery only, and it is gated | No native discovery at all | Skool’s own directory | Strong, inside and outside Reddit | Facebook search and recommendations | Search engines, if you let them index |
| Content compounds publicly | No | No | Mostly no | Yes | No for private groups | Yes, this is the point |
| History limits | Full history, poor retrieval | 90 days visible on free plan | Full history, in-app search | Permanent | Full, hard to search | Permanent and indexed |
| Cost as you scale | Free | Per user, per month | Flat monthly fee | Free | Free | Hosting or subscription |
| You own the member relationship | No emails | Emails, but inside Slack | Yes, with billing | No | No | Yes, fully |
| Structure | Channels plus threads | Channels plus threads | Feed, categories, courses | Threaded posts | Flat feed | Topics and categories |
| Onboarding friction | Low, account is common | Low, invite required | Low, one signup | Lowest | Lowest, account is common | Highest, new account |
The split that matters most: chat versus archive
Conversation inside Discord and Slack is essentially invisible to search engines. Nobody Googling your topic will land in your server. Every single member has to arrive through a channel you paid for or worked for, forever.
Public forums and Reddit work the opposite way. Every answered question becomes a page that can be found for years. Stack Overflow (11.7M) and DEV Community (~4.1M) did not reach that size through invite links; they reached it because a decade of answers kept pulling in the next person with the same problem. r/SaaS (~755K) grows on the same mechanic without its operators owning any of it.
In our experience this is the single biggest regret we hear about. A chat platform feels alive on day one because twenty people are talking. A forum feels dead on day one because three people posted and nobody replied. Two years later the forum has a thousand pages working for it and the chat server has a scrollback nobody reads. If organic growth is part of your plan rather than a nice-to-have, that asymmetry should dominate the decision.
Discord does have its own Server Discovery directory, but it is gated behind minimum size, age and activity requirements, so a new server is not findable there at all. Slack has no equivalent. That is part of why so many Discord and Slack communities end up listed in third-party directories like ours: it is one of the few discovery surfaces available to them.
Slack’s free plan quietly destroys your knowledge base
On the free version of Slack, members can only view and search messages and files from the last 90 days, and Slack states that messages and files more than one year old are permanently deleted. For a work team that is an annoyance. For a community it is structural: the best answer anyone ever wrote in your workspace has an expiry date, and new members cannot learn from what came before.
The obvious fix is a paid plan, and that is where the second trap sits. Slack is priced per user: Pro is $8.75 per user per month billed monthly, or $7.25 billed annually. That model was built for companies, where headcount is bounded and each seat produces revenue. In a community, every successful recruitment drive increases your bill. Run the arithmetic at a thousand members before you commit, then run it at ten thousand. Communities at the scale of dbt Community Slack (100K+) or Product School Slack (100K+) are not paying per-seat rates for a general membership, which tells you what the realistic configuration looks like, and what it costs you in history.
Our data still shows Slack holding a clear niche: it skews strongly to marketing and growth peer groups, where members are already in Slack all day for work and the value is the live conversation rather than the archive.
Cost, ownership, and what you are actually buying
Free is not free. Discord, Reddit and Facebook Groups cost nothing and give you nothing to own. On Reddit and Facebook you cannot export a member list, you cannot email your members, and a policy change or an algorithm change can remove your reach overnight. Discord is friendlier to operators but still gives you no email addresses. If your community exists to support a business, that matters a great deal, and it is worth reading alongside our guide to finding customers in communities.
Skool takes the opposite position: a flat fee rather than a per-member one, at $9 per month on Hobby with a 10% transaction fee, or $99 per month on Pro with a 2.9% fee. You get member records, payments and courses in one place. The tradeoff is that the content lives inside a platform you rent, and mostly does not compound in public search.
A hosted forum is the most work and the most ownership. Discourse’s managed hosting starts at $100 per month, and the software is free and open source if you self-host. You own the domain, the archive, the SEO value and the member data. You also own the moderation, the spam and the empty-room problem in month one.
What the distribution across 200 communities suggests
The patterns are consistent enough to be useful. Developer-tool communities skew to forums and Discord, because their members expect a searchable archive and real-time help. Marketing and growth communities skew to Slack. Course-and-cohort communities skew to Skool, and the strongest single category we track is no-code and AI automation on Skool (16 communities), where paid cohorts, a course library and a members-only feed fit the product exactly. AI Automation Society (~458K) is the scale example. Facebook Groups, at 15 of the 200, is the only platform we would actively steer most new operators away from.
We would suggest matching the platform to how your community creates value. If members mostly need each other in real time, a chat platform is correct and you should plan a separate discovery channel from day one. If members mostly need answers, a forum is correct and you should accept a slower start. If you are selling something with a curriculum, Skool or an equivalent is correct. And if you are still at the beginning, our guide on going from zero to a thousand members covers the part that platform choice cannot solve for you.
