Hello,
If I understood correctly, you need a solution to verify that the login credentials provided by your customers are valid for other utility companies.
I'm an experienced software developer, been working on PHP and NodeJS for over 5 years. Web automation and bots is my passion, and I really mean this.
Sounds like you really need someone who can deliver this, I fully understand your requirements so let me tell you how I'd approach this project.
1. Research - try to group similar authorization-system websites together, find out which ones have captcha and which ones need a full headless browser automation.
2. Preparing testing for each website. On such a complex and varied HTTP calls, it's very important to be able to be able to test the code, so I'd spend quite some time on building unit tests for each login form.
3. Write website-agnostic code for each kind of authorization system, this is where the actual code is written, I'd strongly follow TDD approach because of the nature of this project. A bit easier solution would be to use headless browser option (something like PhantomJS), it will shave-off tens of hours in development but the performance and reliability will suffer. My recommendation would be to do POST request when possible. GET (for csrf token) + POST if required and only after this look into headless browsers.
have to stop here as I'm out of characters limit lol.
Let's have a call and discuss this in more details.
Best,
Nick.