The service looks interesting, but I'm wondering if there's a technical reason why it's a SaaS. CSVs could be parsed entirely on the client, and it should be possible for .XLS/.XLSX as well. If not with pure JavaScript+Web Workers then surely with WebAssembly.
Doing this traditionally on the backend is fine of course, but as others have mentioned, trusting you with potentially sensitive data is a hurdle for many companies and individuals.
To be honest, we haven't thought about the possibility to work everything client side. Its an idea worth exploring.
Our aim is to integrate the importer with multiple destinations such as databases (MySQL, PostgreSQL, S3 etc), APIs (custom, Zapier, GSheets, Airtable) and others (FTP, Email etc). Coding server side would be easier and faster.
Moreover we plan to introduce on-premise deployment options in the future.
Then again, enterprises that deal with sensitive data don’t just allow employees to access that data via a web browser (or should not) and especially not through a modern one. So it would be a huge pain to figure out which browsers are capable of even supporting Wasm and other modern tech.