Clean up a CSV or Excel contact list before your next import. Trim whitespace, normalize emails and merge compatible duplicates while keeping conflicts and invalid addresses visible for review.
Clean your contact list
Runs in your browser. Contact files and pasted rows are not uploaded. Up to 2 MB, 5,000 rows and 40 columns.
What does a contact list cleaner check?
This tool trims leading and trailing whitespace, lowercases the selected email column and checks common email syntax. Rows with the same valid email merge only when all other nonempty fields agree. Empty cells can be filled from a compatible duplicate, with the source row numbers retained.
Conflicting names, companies or other fields keep their separate records and receive a review flag. A row that could match several conflicting records stays separate too. Missing and invalid emails also stay in the output. Phone numbers retain their format because a country code cannot be safely inferred from the number alone.
How to clean a contact list
No account or file upload to a server is needed for the local tool.
01
Load your list
Choose CSV, TSV or XLSX, or paste comma- or tab-separated rows with a header. Select a worksheet when the workbook has several.
02
Choose the email column
Confirm which column identifies duplicates. Clean the list and inspect the before-and-after row counts.
03
Review and export
Check the flagged conflicts and email syntax issues. Download CSV or XLSX with all output records and audit columns.
What contact lists can you prepare?
Keep the original business context alongside the cleaned fields.
Event contacts
Consolidate compatible rows while preserving event names, source and consent fields.
CRM imports
Standardize emails and identify conflicts before mapping the columns to your CRM.
Team spreadsheets
Review overlapping lists without discarding incompatible company or person details.
How does prospect research become a usable list?
Start with source-linked prospect research, then clean and review the resulting records before an import.
Local cleanup is free. This optional next step opens Okou after sign-in and uses credits. Attach your reviewed file there; the local list is not sent automatically.Prepare a CRM import
Start med:
Merge the agreement, keep the conflict
Illustrative example. Use the fictional sample button above to run an actual local cleanup.
Yes. Local cleanup and CSV/XLSX downloads run in your browser without an account. The optional follow-up task in Okou requires sign-in and uses credits.
Are my contact files uploaded?
No. The local cleaner reads and processes files in this browser. It does not upload contacts or send them to Okou. If you choose a follow-up task, attach the reviewed file yourself after sign-in.
Which formats and sizes are supported?
Use CSV, TSV or XLSX files up to 2 MB, with up to 5,000 data rows and 40 uniquely named columns. A workbook is processed one selected worksheet at a time. Save older XLS files as XLSX first.
Does it check whether emails can receive mail?
No. It checks common address syntax only. A syntactically valid address can still bounce or belong to someone else.
What is included in the downloaded file?
All output records, including flagged ones, plus status, source rows, issues and changes. CSV exports prefix formula-like text with an apostrophe. Excel exports store cells as text to preserve identifiers and avoid formula execution.
