Hi, @ShimritLevy - Congrats on choosing monday․com as your new CRM! You may want to set something up with Zapier. You’d need to find a way to trigger each of the objects in Salesforce that you want to move for Zapier to force Zapier to pick it up, however, once you have it triggering in Zapier, you can then create thpse items on the appropriate boards and send it all seamlessly to monday․com (including linkages between items if necessary).
There is an integration limit of 10,000 items per board, so you may still have to do a bit of temporary splitting and merging to handle moving 20k contacts. But it’s definitely a better system to do it with Zapier than manual exports and imports via Excel.