Prepare a HubSpot contacts CSV: checks before import

Check current official requirements first

HubSpot’s official import file guidance explains headers, properties and unique identifiers. Its import overview distinguishes creating, updating and associating records. Requirements depend on the objects and operation you choose. Review them in the account before exporting live data. Sources reviewed 5 October 2026.

For this exercise use a simple contacts-only file and map Email, First Name and Last Name to the corresponding contact properties. Download the synthetic contacts example. These example.com addresses demonstrate structure; they are not real recipients or a mailing list.

Run limited local checks

1. Load the example in the CSV Cleaner & Import Checker. Confirm three headers and two data records with a comma delimiter.
2. Set destination headers to Email,First Name,Last Name. Prepare mapping and inspect every source selection.
3. For this example, mark Email as required and select it as the repeated-key check. That expresses the review rule for this exercise, not a universal rule for every HubSpot import.
4. Run the check, review output and download a small test file. The checker tests nonblank fields and within-file repeated keys, not email deliverability, custom property types or existing account records.
5. In HubSpot, inspect the actual import mode, mapping and warnings. Start with an approved test set; verify which records were created or updated and retain any error report.

Understand common boundaries

Do not collapse account decisions into cleanup

Changing a header does not establish an association. A nonblank email string can still be malformed. A clean file may contain an existing contact that would be updated unexpectedly. Coordinate import permissions, backups and review with the account owner; the browser tool cannot undo a CRM import.

If the workflow repeats, plan custom data import and integration development with explicit source identifiers, destination permissions and recoverable errors. Read the conflicting-ID example before choosing any automated deduplication rule. This page is an independent preparation guide, not a HubSpot affiliation or integration already built into the tool.