List of free data-importer stuff for developerππ½
If you're looking for all programming tools around data-importer (not just free). Check this page List of data-importer Programming Tools

Flatirons Fuse
An easy to install, customizable CSV and spreadsheet importer that makes customer onboarding and data imports a breeze.
Tag: customer-onboarding, csv-importer, spreadsheet-importer, data-importer
Embeddable spreadsheet importer Import up to 10,000 records per month Frontend data validation and cleaning Backend data validation support 1 Template