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Home / Wiki / Contacts & Data Quality

Run a duplicate detection sweep

Updated May 2026

You'll learn how to: Trigger a fresh duplicate detection scan across all your contacts, without waiting for the next scheduled background run.

Time: 10 seconds to start. Results return in 1-5 minutes depending on network size.

Prereqs: Your plan includes data-quality tools. You have at least a few hundred contacts (sweeps on tiny networks aren't useful).

When to use

Nynch's background dedupe job runs on a schedule. You don't normally need to think about it. Run a manual sweep when:

  • You just finished a big import (CSV, LinkedIn export, Gmail history).
  • You merged a teammate's contacts into your workspace.
  • You suspect duplicates exist that aren't appearing on the Possible Duplicates page yet.
  • You changed contact email or LinkedIn URL values in bulk and want to re-check.

Steps

  1. Open the Possible Duplicates page directly: paste this URL into your browser address bar while signed in to Nynch.

    https://app.nynch.com/possible-duplicates

  2. Look in the top-right of the page for the Run scan action (or equivalent refresh button).

  3. Click it.

  4. A toast confirms "Scan started" or similar.

  5. The page shows a loading state while the sweep runs.

  6. New duplicate pairs appear as they're found, up to 50 at a time, sorted by match confidence.

What the sweep checks

  • Email address (exact match).
  • LinkedIn URL (exact match after canonicalisation).
  • Name similarity (fuzzy matching for close variations).

Each candidate pair gets a confidence score. High confidence pairs are typically exact email or LinkedIn matches. Lower confidence is name-similarity only.

After the sweep

For each pair, the same actions as always: Merge (opens the 3-step merge wizard) or Dismiss (permanently silences that pair).

See Find and fix duplicate contacts for the full merge walkthrough.

If something goes wrong

  • Symptom: "Run scan button isn't there." → Fix: Your plan may not include manual sweep, just background sweeps. Contact support if you need it.
  • Symptom: "Sweep finished but no new pairs appeared." → Fix: No new duplicates were detected. This is the expected result if your network is already clean. Re-run after the next big import.
  • Symptom: "Same pair keeps reappearing after I dismiss it." → Fix: Dismissals are permanent for the exact pair. If they reappear, one of the underlying records may have changed (e.g. you updated the email). The "new" pair is technically different from the dismissed one.
  • Symptom: "Sweep takes forever." → Fix: Networks with 10,000+ contacts can take several minutes. Close the tab and come back; the sweep runs in the background regardless.

Related: Find and fix duplicate contacts | CSV import step by step.