Reddit Viral Radar — Trending Posts

Find Reddit posts that stand out in the communities you follow. Compare each post with a sample of similarly aged posts from the same subreddit, then export ranked discussion links and metrics.

Use it for content research, community monitoring, campaign ideas and finding discussions worth reviewing.

Quick start

1. Enter subreddit names, such as hiking and camping.
2. Choose a maximum number of results and optional score, comment or approval filters.
3. Set a spending limit. For two communities, start with an $8 maximum charge and a 480-second collection budget.
4. Run the Actor and open Overview. Check the run summary for coverage before treating the scan as complete.

{
  "subreddits": ["hiking", "camping"],
  "maxResults": 25,
  "maxBaselinePerSubreddit": 60,
  "maxCandidatesPerSubreddit": 30,
  "minScorePercentile": 0.7,
  "maxRunSeconds": 480,
  "region": "US"
}

maxResults is a maximum, not a guaranteed count. Availability, filters, the baseline sample and your limits affect the result.

What the scores mean

Field	Meaning
scorePercentile	Relative score among similarly aged baseline posts in the same community
commentsPercentile	Relative comment count among that baseline
resonanceScore	Mean of the available percentiles, from 0 to 1
upvoteRatio	Approval ratio, used as an optional independent filter
confidence	ok, insufficient or degenerate
scoreSampleSize, commentSampleSize	Available baseline observations for each metric

The baseline comes from the community's new listing; candidates come from hot, rising and top. Comparisons use age groups: under 1 hour, 1–6 hours, 6–24 hours, 24–72 hours and over 72 hours.

Each metric needs at least 10 baseline observations with some variation. Unsupported percentiles remain null. Posts with insufficient baselines may still appear with raw metrics when no percentile threshold excludes them; they rank after supported scores.

A high score indicates relative community resonance at this observation. It does not establish future growth or count views. Reddit score is upvotes minus downvotes; comment count measures volume, not reply-tree depth.

Inputs

Input	Default	Purpose
subreddits	Required	Communities, with or without r/; duplicates are removed
maxResults	50	Maximum saved posts, up to 200
maxBaselinePerSubreddit	120	Baseline sample cap
maxCandidatesPerSubreddit	60	Candidate cap per community
minScorePercentile	0	Optional minimum, 0–1
minCommentsPercentile	0	Optional minimum, 0–1
minUpvoteRatio	0	Optional minimum approval ratio, 0–1
maxRunSeconds	480	Collection budget, 30–900 seconds
region	US	Access location; it does not filter posts by author country

The time budget starts after initialization. Startup, cleanup and an active page can extend total run time. Collection also stops when the spending limit prevents further work.

Output and coverage

Each row includes the post ID, subreddit, author, title, absolute postUrl, content url, raw metrics, age, percentile scores, confidence, sample sizes and observedAt.

• Overview: ranked posts, strongest supported scores first.
• Metrics: approval, activity and sample sizes.
• Links & authors: original discussion/content links and identifiers.

The OUTPUT key-value record reports totals, applied filters, excluded counts, source outcomes, billing counters and any stopped reason. PARTIAL means the selected time or spending limit stopped collection; saved rows remain available. The platform can show a successful run while this summary correctly reports partial coverage.

Recognized blocks or exhausted request errors are reported. If all candidate sources are unavailable, the Actor fails clearly. A valid search with candidates excluded by filters can succeed with zero rows. Some communities can be inaccessible or have too few baseline posts.

Pricing

Event	Price
Run start	$0.05 per started GB of memory, minimum one GB
Reddit listing-page attempt	$0.65
Unique post saved to the run dataset	$0.02

At the default 2 GB, the start fee is $0.10. Listing attempts include baseline, hot/rising/top pages and retries, including blocked pages or work that yields no matching posts. Browser resource files are not separate events. Results are charged once per saved dataset row; a post saved in a later run is charged again.

Examples without retries:

• One community, four listing pages and 20 saved posts: $3.10.
• Two communities, eight listing pages and 25 saved posts: $5.80.
• Four listing pages and no saved posts: $2.70.

These are billing examples, not promises of page coverage or result count. A short budget can stop the run before a candidate listing is read. A $1.45 maximum charge is supported for a small attempt; $8 gives more room for the two-community example. The Actor checks spending before navigation and output writes.

API and integrations

Use Actor ID j46hGtiSapQuIqF31 so your integration remains stable if the Store name changes:

POST https://api.apify.com/v2/actors/j46hGtiSapQuIqF31/runs?maxTotalChargeUsd=8
Authorization: Bearer YOUR_APIFY_TOKEN
Content-Type: application/json

Send the JSON input above as the request body. Poll the returned run ID:

GET https://api.apify.com/v2/actor-runs/RUN_ID
Authorization: Bearer YOUR_APIFY_TOKEN

Read rows from the returned default dataset and coverage from the default key-value store:

GET https://api.apify.com/v2/datasets/DATASET_ID/items?clean=true&format=json
GET https://api.apify.com/v2/key-value-stores/KEY_VALUE_STORE_ID/records/OUTPUT
Authorization: Bearer YOUR_APIFY_TOKEN

Schedule recurring snapshots in Apify or connect results to your automation tools and database. Compare separately stored runs if you need changes over time.

This Actor is an independent research tool and is not affiliated with Reddit.