How to find subreddits for any topic before you post

To find subreddits for a topic, search Reddit for the problem people have, not the product, then look at which communities the matching posts come from. Use r/findareddit for niche requests, and a related-subreddit map to move sideways from a sub you already know. If you need lists for many topics, or want an agent to do the work, a subreddit finder API returns names, sizes and descriptions as JSON.

Finding a subreddit is the easy part. Whether your first post survives depends on checking each one's rules, activity and posting settings before you join in. This guide covers both.

Four ways to find subreddits

Use at least two, because each one misses communities the others catch.

Find subreddits with Reddit search

Reddit's help center says to type into the search bar and "you’ll see suggestions for specific communities and profiles," then select "Search for [query]" to see full results including posts (Reddit Help, checked Oct 14, 2026).

The suggestions match on names. Search "crm" and most of what comes back is subreddits with CRM in the name. The post results are more useful. They show which communities discuss the topic, whatever those communities are called. Sort by Top with a past-year time filter to see where the well-received discussions happened. Reddit's sort and filter page lists the options.

How to find subreddits through r/findareddit

r/findareddit exists for this. It had 660,647 subscribers as of Oct 14, 2026, and its sidebar describes a directory that "indexes 1,000+ up-to-date subreddits, categorized into 50+ different categories." Post what you're looking for and someone usually replies with a community you'd never have searched for. It works best for personal and niche topics, where the right sub has a name you couldn't guess.

Related-subreddit maps

Tools like Andrei Kashcha's similar reddits answer "Redditors who read /r/X also read" from audience overlap. Start with one sub you know is right and you'll find its neighbors, including smaller ones that never show up in search.

Use a subreddit finder API

GET /v1/reddit/subreddits/search takes a topic and returns matching communities, each with its name, description, subscriber count, creation date and NSFW flag. Each page costs 2 credits.

curl "https://api.chatterapi.com/v1/reddit/subreddits/search?q=saas" \
  -H "Authorization: Bearer $CHATTERAPI_KEY"

{
  "data": [
    { "name": "SaaSMarketing", "subscribers": 37320, "nsfw": false },
    { "name": "B2BSaaS", "subscribers": 30565, "nsfw": false },
    { "name": "SaaS_Email_Marketing", "subscribers": 14215, "nsfw": false },
    { "name": "SaaS", "subscribers": 820451, "nsfw": false },
    { "name": "microsaas", "subscribers": 219914, "nsfw": false },
    { "name": "micro_saas", "subscribers": 140248, "nsfw": false },
    { "name": "SaasSelection", "subscribers": 4033, "nsfw": false },
    { "name": "SaaSMarketingHub", "subscribers": 116, "nsfw": false }
  ],
  "page": { "nextCursor": "ASezT4MJdOzO…", "hasMore": true },
  "credits": { "charged": 0, "remaining": 719 }
}

This sample comes from a test key, which returns one recorded real response per endpoint for free. It's trimmed to the useful fields. Subscriber counts run from 820,451 down to 116, and two results are near-duplicates (microsaas and micro_saas). You still have to check a raw list for fit, and that's the next step. The free subreddit finder runs the same search in a browser.

Rules and moderators aren't in the search results. You get those with a second call.

Check fit before you join

For each candidate, GET /v1/reddit/subreddits/{name} returns rules, moderators and posting settings for 2 credits. The script below finds communities for a topic and flags the ones whose rules restrict promotion:

import os, requests

KEY = os.environ["CHATTERAPI_KEY"]
H = {"Authorization": f"Bearer {KEY}"}
BASE = "https://api.chatterapi.com/v1/reddit/subreddits"
WATCH = ("promot", "spam", "self-promo", "selling", "advertis", "solicit")

def find_and_check(topic, min_subs=1000, limit=10):
    found = requests.get(f"{BASE}/search", headers=H,
                         params={"q": topic, "limit": 25}, timeout=30).json()["data"]
    found = [s for s in found if (s["subscribers"] or 0) >= min_subs and not s["nsfw"]]
    for s in found[:limit]:
        sub = requests.get(f"{BASE}/{s['name']}", headers=H, timeout=30).json()["data"]
        rules = sub["rules"] or []
        strict = [r["title"] for r in rules if any(w in r["title"].lower() for w in WATCH)]
        posting = sub["posting"] or {}
        print(f"r/{s['name']:<22} {s['subscribers']:>9,} subs  "
              f"{len(rules):>2} rules  restricted={posting.get('restrictPosting')}")
        for title in strict:
            print("    promo rule:", title)

find_and_check("saas")

A topic search plus ten fit checks costs 22 credits. On the r/SaaS profile alone, the check prints three promotion rules: "No Vendor Spam on posts or comments", "No selling, soliciting, or fundraising" and "No Promotional or Advertising SaaS". You can still post there. Read the full rule text first, and go in to answer questions rather than to link.

For activity numbers (posts per day, comments per post, what the top posts reward), see how to size up a community with subreddit stats.

New account restrictions

The most common reason people can't post in the subreddits they find is the account, not the sub. In r/findareddit, someone asked how to find niche communities "that don't have new account restrictions," because every comment "just gets auto-modded immediately" (u/StarRecur). The top reply: "Make friendly helpful comments on some new-user-friendly subreddits. Comment on existing discussions, rather than posting new ones" (u/SnooDonuts6494). Another reply suggested messaging the mods for permission if you're offering free help.

Find subreddits from where people already talk

The most reliable way to find the best subreddits for a niche is to search the posts and count where they live. GET /v1/reddit/search returns each post with its subreddit, at 2 credits per page:

curl "https://api.chatterapi.com/v1/reddit/search?q=best+crm+for+small+business" \
  -H "Authorization: Bearer $CHATTERAPI_KEY"

In our sample of 25 results for that query, the subreddits break down like this:

Searching communities for "crm" would have found the first two. It wouldn't have surfaced r/smallbusiness, where buyers ask the same question in a general setting. Run a few phrasings of the problem ("best X for Y", "alternative to Z", "how do you handle W") and tally the subreddits. The ones that keep appearing are your shortlist. For a full research loop built on this, see how to find customer pain points on Reddit.

Small subreddits often beat big ones

It's tempting to sort by subscribers and start at the top. People who've tried both sizes often report the opposite. In r/SaaS, one founder wrote that a post in a big entrepreneur sub got "20K+ views, 42 comments" and "not a single visitor," while "the posts that produced real leads... were in tiny niche subs. A few hundred views each" (u/decebaldecebal).

The same thread has a fair counterpoint. A commenter argued the big-sub post wasn't wasted, because "those 42 comments aren't missed leads, they're a language bank," and suggested: "use the big sub as research, not distribution" (u/Agitated_Offer_4343).

Both points hold. Large subs show you how people describe a problem. Small subs are where people still have it. So treat them differently: read the big ones and take part in the small ones.

Find subreddits now

Try the free subreddit finder, then check your shortlist with subreddit stats. If you're working from code or an agent, the same endpoints are available over REST or the hosted MCP server. Our Reddit API guide covers the rest. Once you know where your buyers talk, build a lead finder agent to watch those communities.

ChatterAPI gives your code and your agents Reddit and X data through one key, over REST or MCP, and you don't have to apply for a developer account. Sign up with Google to get 100 free credits without a card. Plans start at $19/month for 25,000 credits.