A long time ago, before I did anything marketing related, I saw video about a guy who bought and sold cars.
The main idea was find out what the fastest selling car was (for under $3000).
It may seem obvious, but car-flipping is not much different than promoting on Reddit.
Everyone wants to post on the Reddits with large amount of users and activity. And, if your post can land well in them, great. You should still go for it (while following posting best practices.)
But, I can’t tell you how many times my posts did much better in a smaller subreddit.
So, in this post, we’re going to talk about why finding the FASTED GROWING subreddits, small, highly active, and almost no competition is the secret ingredient you need to be successful on Reddit.
Especially if you’re a founder, a marketing agency, or selling a niche brand.
But, how do you find these small, niche subreddits? They aren’t necessarily the ones immediately popping up when you do a search.
How Subriff changed my Reddit game
There are many Reddit search apps to help you find your Reddit Market Fit, but many of them (like Gummy Search) are only free to a certain extent.
And, if you’re reading this post, you’re probably not quite at the stage where you should be paying for any of these tools just yet.
I’ve been using a site called Subriff lately. It’s free, and can help you find a whole plethora of little-known subreddits.
But, my favorite feature from this tool?
It can tell you exactly what the fastest growing subreddits are in that niche.
And, it’s simple, easy to use, etc.
Oh, and did I mention…IT’S FREE.
How to use Subriff
Go to Subriff.com
Put in your filters and keyterms - I select ‘Monthly’ under ‘Order by growth rate’
The subreddits will appear. Whatever is at the top is the fastest growing.
Click on that, and you can see how many users are in that subreddit.
You’ll already see which ones are growing the fastest. But, what’s considered ‘small’? According to the AI Overview:
“Small (under ~25k) are niche with less moderation; Medium (~25k to 1M) have established topics with daily activity and some rules; Large (1M+) cover popular culture, brands, or big topics, requiring heavy moderation; while tiny ones (under 1k) are often inactive, but even a few thousand members can put you in the top half of active subreddits.”
So, in layman’s terms: If it’s under 25K members and in the three digits in terms of growth, it’s a goldmine.
Of course, after this you’ll still have to explore that subreddit to make sure its a good fit for you. But, taking into consideration that growth can give your post that it needs.
Understanding the logic
So why focus on the fastest-growing subreddits?
We’re not flipping cars but the same market dynamics apply.
Fast-growing subreddits give you asymmetric upside.
Here’s why 👇
You arrive before saturation
Fewer marketers
Fewer copycats
Less “Reddit fatigue” from users
Your posts get more visibility
Fewer posts competing for attention
Higher chance of hitting the front page of that subreddit
Engagement compounds faster when the community is small + active
You learn the culture early
You understand what gets upvoted before norms harden
You can shape tone, expectations, and standards
You’re not guessing, you’re observing in real time
You build reputation, not just reach
Early contributors stand out
Familiar usernames earn trust
Trust > traffic on Reddit
Growth does the work for you
As the subreddit grows, your past posts keep paying dividends
Comments, DMs, profile clicks stack over time
You ride the wave instead of chasing it
The Bottom Line
Big subreddits = Loud, crowded, competitive, fragile
Fast-growing small subreddits = Quiet, high-signal, forgiving, leverage-rich
The simple rule of thumb
Under 25K members
Consistent 3-digit monthly growth
Clear niche + active comments
And if you’re a founder, agency, or niche brand?
This is how you win on Reddit without ads, spam, or burning accounts.
Got it?
Now give it a try.
