Build basic API & file uploader for email finder

Here's the general job description:

- We have a lot of .csv files we need to enrich with work emails in bulk
- For this enrichment we're using a 3rd-party API
- We need you to build an API we can POST either a file to or a file_url (S3 hosted file), or a list of files
- These files are enriched with emails using the 3rd-party API, emails are then validated using another API, and files are merged into one final
- Once finished, the results are posted to a webhook

Please let me know if you have experience with:
- Email finding APIs in general
- Requests throttling / paralelization
- CSV data parsing en reconstructing