Clean a CSV before a HubSpot import
To clean a CSV for a HubSpot import, fix the phone column to E.164, lowercase and validate the email column, then remove duplicate rows by email — in that order. Sigmera does all three in your browser, so your contact list is never uploaded to a server and stays GDPR-safe by design.
Last updated: June 2026
Why messy exports break the import
A CSV exported from a webform, an old spreadsheet, or another CRM almost never lines up with what HubSpot expects. Phone numbers arrive as (415) 555-0132, 415.555.0132, and +1 415 555 0132 all in the same column. Emails have stray capitals and trailing spaces. The same person appears three times. When you push that into HubSpot, the import either fails outright, silently drops rows, or — worse — creates duplicate contacts that pollute your database and inflate your seat count. Cleaning up afterwards inside HubSpot is slow and error-prone. It is far cheaper to fix the file first.
If your list is still an Excel workbook, save it as a CSV first — HubSpot imports comma-separated files, and working in plain text keeps every cleanup step below predictable.
Step by step: prep your CSV for HubSpot
- 1. Clean the phone-number column. Open the phone-number cleaner and convert the whole column to E.164 (
+14155550132) so HubSpot stores it as a valid phone property. - 2. Normalise the email column. Open the email-column cleaner to lowercase, trim, and validate addresses, dropping the ones HubSpot would reject.
- 3. Remove duplicate contacts. Open the duplicate remover and match on the email column so each contact appears once.
- 4. Preview, download, and import. Check the cleaned preview, download the file, and map the columns in HubSpot’s import wizard.
Before and after
| Field | Messy export | HubSpot-ready |
|---|---|---|
| Phone | (415) 555-0132 | +14155550132 |
| [email protected] | [email protected] | |
| Duplicate rows | 3 rows, same email | 1 row |
| Import result | Errors / duplicate contacts | Clean import, no duplicates |
🔒 Your contact list stays on your device. Every step runs in your browser’s memory — no file is uploaded, which keeps customer PII GDPR-safe by design.
Frequently asked questions
- Why does my HubSpot import keep failing?
- The most common causes are phone numbers in inconsistent formats, invalid or blank email addresses, and duplicate rows that collide on the same email. Cleaning the phone column to E.164, validating emails, and removing duplicates before you upload fixes the majority of failed HubSpot imports.
- What phone format does HubSpot expect?
- HubSpot stores and validates phone numbers best in E.164 format — a plus sign, country code, then the number with no spaces or brackets, like +14155550132. Sigmera's phone cleaner converts a messy column to E.164 in your browser before you import.
- Will this upload my contact list anywhere?
- No. Every step runs inside your web browser using client-side JavaScript. Your contact CSV is never sent to a server and never leaves your device, so handling customer PII this way is GDPR-safe by design.
- Should I deduplicate on email or on the whole row?
- For a HubSpot import, deduplicate on the email column. HubSpot uses email as the primary key for contacts, so two rows with the same email are the same contact even if other fields differ. Matching on email removes the duplicates HubSpot would otherwise merge or reject.