Which subreddit should I start with?

None of the founder ones. Start in the room your buyer already sits in. Spend the first week only reading. If you sell to founders, r/SaaS and r/startups are your buyer subs. The whole split goes away. And that's where a lot of Reddit advice comes from. It's written by people who sell to founders.

Why do my posts in big founder subs get ignored?

Because you're up against everyone else who read the same list. The big subs get the most launch posts. That's why they also have the tightest rules. Smaller rooms get fewer posts a day, so a good one is still there tomorrow.

How do I find the subreddit my buyers are in?

Search Reddit for the words they'd use for the problem. Not the words you'd use for your product. Your buyer never types 'workflow automation platform'. They type 'every Friday I put this into a spreadsheet by hand'. Then look at which subreddit those complaints keep coming from. After twenty results or so, you'll see which room it is.

Is a small subreddit worth posting in?

Often it's the best one you have. A thousand people with the same job title beat a million. The million only share one thing. It's the word 'entrepreneur'. Judge a room by how many posts spell out your problem. Not by the number in the sidebar.

Can I post the same thing in ten subreddits?

That's the fastest way to a shadowban. And nobody tells you it happened. Your posts stop showing to anyone but you. Cross-posting the same text is the pattern spam filters are tuned for. One room, one post written for that room.

Best Subreddits for Founders (Your Customers Aren't in Them)

Sorted by job. For feedback, r/SideProject or r/roastmystartup. For testers, r/AlphaandBetausers. For advice from people who run things, r/startups and r/Entrepreneur. For peers in your trade, r/SaaS and r/smallbusiness. But the sub that gets you customers is almost never a founder sub. It’s wherever your buyer complains.

TL;DR

“Best subreddits for founders” hides two questions. Where do founders hang out? And where are my buyers? Those two lists barely match.
Founder subs are good at four jobs. They tear your idea apart. They find you testers. They get a launch seen. They pass on advice from people who run things. None of those is demand.
Pick the room by the job you have this week. Not by the number in the sidebar.
The room that matters is where people spell out your problem in their own words. Nobody asked them. It takes about twenty searches to find.

The question behind the search

Search for “best subreddits for founders”. You get back a ranked list of the biggest rooms where founders gather. That list is accurate. It is also not what you needed.

Two different jobs hide behind the same phrase. One is I want to talk to people like me. That’s fair, and the founder subs do it well. The other is I want customers. For that job, founder subs are close to the worst place you can stand. Everyone there is selling. Nobody there is buying. Unless, of course, you sell to founders. Then your buyer sub and your peer sub are the same room. You have it easy. And it’s why so much Reddit advice comes from people in that spot.

For everyone else, the useful move is to sort by job.

Best subreddits for founders, by job

The job this week	Where	What you’re walking into
Get the idea torn apart	r/roastmystartup	Roasting is the point, so nobody minds a link. Expect blunt words. That’s the trade.
Recruit early testers	r/AlphaandBetausers	Made for founders who need people to try unfinished things. Low volume, high fit.
Show a working thing	r/SideProject	Built for show-and-tell. The unwritten bar is that it has to work. A waitlist page reads as a pitch, not a project.
Learn from operators	r/startups, r/Entrepreneur	Promotion goes in one thread the moderators set up for it. Direct links get removed. Come for the reading and the comments.
Talk shop with peers	r/SaaS, r/smallbusiness, r/EntrepreneurRideAlong	People running the same shape of business as you. Best for questions about how, not for launches.

Two things to check before posting anywhere on that list. Read the sidebar first. These rooms change their rules. The version you read in a blog post is always a bit out of date. And check whether the sub runs a promotion thread. Several of the big ones do. Posting outside it is the top reason a first post vanishes.

You can get removed. You can get shadowbanned. You can get ignored. Each is its own subject. We covered all three in how to get users from Reddit. Inside: account age, the karma floor, and why the old 90/10 rule is dead. It also has a comment template that doesn’t read like marketing.

The subreddit no list can name

Now the part that matters.

Somewhere on Reddit, people are talking about your problem. They use their own words. They have no idea a founder is reading. They’re not asking for a product. They’re venting about a Friday afternoon. Or asking which of two bad workarounds is less bad. That room is worth more than all the subs in the table above put together. And it doesn’t have the word “startup” in its name.

Sell to managed service providers? Then it’s r/msp. Sell to bookkeepers? Then it’s r/accounting. Or r/photography and r/Frontend. Or r/HVAC and r/nonprofit. Or r/Etsy and r/paramedics. The list is as long as the economy. That is why no list can name yours.

It beats the founder subs for one reason. Nobody asked them. A complaint nobody asked for is as close to free evidence as you’ll get. Nobody is being polite to you. Nobody is guessing at what they might do in future. They already did the thing. And they were annoyed enough to type about it.

Find your buyer’s subreddit in an afternoon

Search their words, not yours. That’s the whole trick. Most founders get it backwards on the first try.

Write down the problem the way the person who has it would say it. Not “invoice reconciliation platform”. Try: “Every Friday I sit and match payments to invoices by hand.” Three or four phrasings.
Search Reddit for each phrasing. Read twenty results. Don’t click on anything of your own.
Note which subreddit keeps showing up. After twenty results, one or two rooms have come up again and again. That’s your answer, and it’s usually a surprise.
Read that room for a week before you say anything. You’re looking for three things. How do they name the problem? Which workarounds do they use? And how much money do they say it costs? Those phrases are your landing-page copy. The buyer wrote it for you.
Then go back to the founder subs for the job they do well. That job is having someone tell you the thing is confusing. Better a founder than a stranger.

Step 4 is the one people skip and the one that pays. What you collect here is evidence. It feeds a real test. It doesn’t replace one. The pass and fail marks are in our four-gate framework. Once you have the room, read getting your first users. It covers how to turn readers into people who show up.

When to stop reading and start testing

You’re done when you can predict what the next complaint will say. That takes about a week of reading. It beats counting posts. A count tells you that you hit a quota. This tells you the room has nothing new to say. Sorting what you read into venting, workarounds and people asking for a fix is its own job. That’s in how to find customer pain points on Reddit.

At that point you have three things: the room, the words, and a claim about what people want. Only the third one is a guess. A cheap test settles it. Put the promise on a page and see if strangers act. That’s about two weeks and under $200. Being wrong for three months costs more.

This is also the part we built a product around. Finding the rooms and pulling the exact complaints is slow work. And it’s the same twenty searches every time. If you’d rather not do it by hand, that’s what a ProofMachine run does. It finds the rooms and the complaints, and every quote links to its thread. But the method above works fine with a free afternoon. And you should know how it works either way.