Reddit Niche Subreddit Scraper (Auto-Tagged)

Scrape posts from a curated list of niche subreddits, with optional keyword search and automatic content tagging. Built for ML/LLM training pipelines, social listening, brand monitoring, and trend detection on niche communities that generic scrapers miss.

What it does

• Pulls posts from any list of subreddits (no auth, no API key)
• Filters by sort order (hot/new/top/rising), time window, min upvotes, min comments
• Optional within-subreddit keyword search
• Auto-tags every post with your custom keyword list — search the body+title for terms you care about, output them as a tags array
• Returns clean structured JSON, ready to drop into ML pipelines or Slack/Notion automations

Use cases

LLM training data — Curate subreddit-specific corpora for fine-tuning domain models (e.g. r/MachineLearning + r/LocalLLaMA + r/datascience for AI dev models).

Social listening (niche) — Track brand mentions or competitor names across vertical subreddits without paying enterprise tools.

Trend detection — Auto-tag posts in r/startups, r/SaaS, r/Entrepreneur for emerging product categories or pain points.

Content discovery — Find high-engagement posts (>100 score, >50 comments) in your niche for content marketing inspiration.

Input

{
  "subreddits": ["MachineLearning", "datascience", "LocalLLaMA"],
  "sort": "hot",
  "searchQuery": "RAG",
  "tagKeywords": ["RAG", "fine-tuning", "Llama", "evaluation", "agent", "embedding"],
  "maxPostsPerSubreddit": 25,
  "minScore": 5,
  "minComments": 0,
  "includeBody": true
}

Field	Type	Default	Description
subreddits	array	required	Subreddit names (without /r/)
sort	enum	hot	hot / new / top / rising
timeFilter	enum	week	hour / day / week / month / year / all (only for sort=top)
searchQuery	string	(none)	Optional keyword search inside each subreddit
tagKeywords	array	[]	Auto-tag keywords applied to title+body
maxPostsPerSubreddit	int (1-500)	25	Cap per subreddit
minScore	int	5	Skip posts below this upvote count
minComments	int	0	Skip posts below this comment count
includeBody	bool	true	Include selftext body in output

Output

One dataset item per post:

{
  "id": "1abcxyz",
  "subreddit": "MachineLearning",
  "title": "[D] Best practices for evaluating RAG systems in production",
  "body": "...",
  "author": "user123",
  "url": "https://www.reddit.com/r/MachineLearning/comments/1abcxyz/...",
  "linkUrl": "https://arxiv.org/abs/...",
  "score": 234,
  "upvoteRatio": 0.97,
  "numComments": 56,
  "createdUtc": 1730000000,
  "createdAt": "2026-04-29T10:00:00Z",
  "isSelf": true,
  "flair": "Discussion",
  "domain": "self.MachineLearning",
  "tags": ["RAG", "evaluation"]
}

Pricing

Currently FREE during the launch preview — no per-result charges, no monthly cap.

When paid pricing rolls out (notice will be posted at least 14 days in advance):

Event	Price
Actor start	$0.01 (one-time per run)
Result item	$0.001 (per post)

Cost examples (post-launch):

• 100 posts: ~$0.11
• 1.000 posts: ~$1.01
• 10.000 posts: ~$10.01

Limits

• Source: Reddit public JSON API (no auth required, no API key)
• Rate limit: ~1 req/sec (politely paced internally with 0.6s sleep)
• Max posts per subreddit: 500 per run (cumulative pagination)
• No private subreddits, no NSFW filtering bypass
• No comment scraping in v1 (planned for v2)

Source attribution

Data comes from Reddit's public JSON endpoint (/r/{sub}/.json), which does not require authentication. Subject to Reddit's Public Content Policy.

Author

Polara Data — niche scrapers for Italy, EU & global markets.