Odoo has a built-in import tool for CSV and Excel files that maps columns to fields and validates the data before importing.

Recommended order

• Clean the data first: remove duplicates, unify names and fix missing codes.
• Import master data in dependency order: categories, products, customers and vendors, then employees.
• Use External IDs so related records link correctly and re-imports update instead of duplicating.
• Import opening balances and open invoices at a clear cut-off date.
• Test the import on a copy database and reconcile totals with the old system.

Keep the import files as part of the project records; they are useful for audits and for repeating the migration if needed.