Salesforce Lead vs Contact Preflight Matcher

Nothing uploadedTested up to 200 MB

Check incoming Salesforce Leads against an existing Contact export by Email or another exact key, review collisions, and download only new Leads.

Compare exactly 2 Salesforce CSV exports locally in your browser: an incoming Lead list and an existing Contact export. Email is selected automatically when both files contain it, or you can choose another shared exact key. Leads whose key already exists in Contacts are flagged for review; only new Leads are written to the downloadable Salesforce-ready CSV. Each file can be up to 200 MB, with 400 MB total. Files are not uploaded to Nablyx.

Processed locally in your browser

Salesforce Lead-to-Contact preflight

Use the incoming Leads CSV as the candidate list and a current Contacts export as the collision check. Matching is exact after surrounding whitespace is trimmed.

Incoming Leads CSVDrop CSV hereor choose a fileCSV up to 200 MB · processed locally

Existing Contacts CSVDrop CSV hereor choose a fileCSV up to 200 MB · processed locally

Preflight results will appear here

Choose Leads and Contacts CSV files, confirm the exact match key, and run the preflight.

Check Salesforce Leads against existing Contacts before import

1
Choose the incoming Leads CSV and the existing Contacts CSV export.
2
Confirm Email or select another exact key present in both files.
3
Run the preflight to separate Contact collisions from new Leads.
4
Review every matched Lead before deciding how it should be handled in Salesforce.
5
Download the new-only Lead CSV and use it in your normal Salesforce import workflow.

Built for the real task

Email default with any shared exact key selectable
Matched Leads separated from genuinely new Leads
New-only CSV export keeps the original Lead columns
Browser-local processing up to 200 MiB per file

See the transformation

A useful diff separates every kind of change.

See changed, added, and removed rows separately so you know exactly what needs attention.

Result

Changed1001, starter1001, pro

Removed1004, pro

Added1006, pro

Changed rows1

Added rows1

Removed rows1

Browser limits

Files are limited to 200 MB to protect browser stability, especially on phones. Processing stays on this device.

Email default with any shared exact key selectable

Check incoming Salesforce Leads against an existing Contact export by Email or another exact key, review collisions, and download only new Leads.

Private by design

The selected file is not uploaded to Nablyx.

Processed locally in your browser

No. This tool reads and transforms the file locally in your browser.

Common uses

Email default with any shared exact key selectable
Matched Leads separated from genuinely new Leads
New-only CSV export keeps the original Lead columns
Browser-local processing up to 200 MiB per file

Does a match mean the Lead and Contact are definitely the same person?

No. An exact key match means the selected value already exists in the Contact export you supplied. Review the collision before deciding whether to skip, update, convert, merge, or otherwise handle the record in Salesforce.

How to Match Salesforce Leads Against Existing Contacts

Common Salesforce Lead Import Collisions with Existing Contacts

Salesforce Lead Import Best Practices Before You Upload a CSV