[snom380]

Our startup needed to automate our invoicing process. Back in the day there were only a couple of reasonably priced, web based ERP systems in our country.

The one we picked had good API docs, but we didn't read the fine print - API access was a high yearly fee, costing almost as much as the regular subscription fee.

Their web interface functionality for importing orders/invoices from a CSV file, and looking at the browser requests I could see they were simply using the API in their frontend. A couple of hours later, and we had our invoice import job doing POST requests to their login page, getting the right cookies back and uploading invoice files.

Worked fine for years, only requiring a couple of updates when they changed their login page.

[bluelightning2k]

I've done a lot of this type of thing! Great example.