mark the answer
When a duplicate is actually the best existing answer, flag it as canonical instead of treating every repeat the same.
dupe-detector.
A Reddit-native duplicate-review tool with a simple promise: show repeat posts before they become moderator cleanup, then redirect the right ones toward a canonical thread instead of just removing them. This page turns the app listing, Devpost submission, demo video, and feedback threads into one shareable proof surface.
public project
Devpost live
walkthrough
43.88 sec
proof set
4 screenshots
community pulse
2 live threads
redirect is better than remove.
The strongest mod-tool version of duplicate detection does not end at a takedown. dupe-detector now lets moderators mark a repeat post as the canonical answer thread for that topic, so the precheck can point future users at the place where the conversation already exists.
surface it early
The poster precheck can show that canonical thread before the next duplicate gets posted, which saves mod time and user friction.
keep the queue explainable
Mods still keep discretion. The app just makes the redirect path obvious when removal would be the wrong first move.
walkthrough
The demo moves through the two real surfaces that matter: a poster-side precheck that catches likely repeats before submission, and a moderator queue that keeps duplicate cleanup fast and explainable.
the two workflows, shown cleanly.
This is the shareable artifact missing from the main Reddit hub: a judge-safe and mod-safe place that shows exactly what the tool does without forcing someone to dig through a raw asset directory.
poster precheck
Show the likely repeats before the user hits submit. The point is not to police intent. The point is to surface the closest threads early enough to save mod time.
moderator queue
Keep the cleanup lane boring: see the strongest suspects, compare them fast, then lock, remove, or leave without queue archaeology.
clean state
The tool should also know when to get out of the way. A clean board matters as much as a flashy catch if the app is going to earn moderator trust.
live-data proof
The support set includes a live public-data render, not just mocked states. That matters for Devpost judges and for any mod deciding whether the app feels real.
Three steps, no external API, no LLM.
If you moderate a subreddit where repeats are a recurring cleanup tax, dupe-detector is meant to install in minutes. It runs entirely inside Devvit — no off-platform data, no scheduler, no `http` permission. Mods see a duplicates queue; posters see a precheck.
open the listing
Go to developers.reddit.com/apps/dupe-detector and press Install. Reddit will ask which subreddit you want to add it to — pick the one you mod.
open the mod queue
From your subreddit's mod tools, open dupe-detector → duplicates queue. The first scan pulls recent posts and groups likely repeats with similarity scores.
tune and forget
Adjust the similarity threshold once for your sub's tone, then leave it. Posters get the precheck card automatically; mods only see suspects, not the rest of the feed.
good fit
Q&A subs, news subs, deals/coupons, fandoms with recurring questions, anything where the same thread keeps coming back.
not the fit
Pure discussion subs where similar topics are by design, or subs where post volume is too low to need a queue. The app silently stays out of the way.
paste this into your mod-team chat
found a mod tool that might cut our duplicate cleanup work: dupe-detector — Devvit-native, no external API, no LLM. posters get a precheck card before submitting; mods get a duplicates queue for the last 7 days with similarity scores and one-click lock/remove/leave. listing: https://developers.reddit.com/apps/dupe-detector proof page (video + screenshots): https://voiddo.com/reddit/dupe-detector/ devpost: https://devpost.com/software/dupe-detector install takes a couple of minutes. worth a 1-week trial?
Recent public feedback threads, not reposted spam.
We already used the dev subreddit for small feedback asks. The next move is not another duplicate post in the same community. It is sharing this cleaner proof surface in mod-tool contexts where rules allow and the problem is already visible.
the false positive museum is open
This is the current live thread asking for ugly near-duplicates and edge cases. It follows the Reddit rule set: ask for examples, not installs; tune around moderator pain, not contest bragging.
small duplicate-hunting check-in
The earlier check-in stays relevant as a baseline reference: where did the tool feel useful, and where did it feel annoying? Keeping both threads public helps future outreach stay specific instead of repetitive.