How to work with browsers (N: fill out the form) in Java or Python?

Question

Python

Hello!
How to work (manipulation, interaction) with browsers ( fill out a form ) in Java or Python languages ?
Imagine there is a program with a customer database. This program should fill out the form of the site opened in a browser (Internet Explorer, Mozilla FireFox, Opera, Chrome). That is in another program! The site does not have an API, so you can send current data through the site form.
How to do it? :

• How to work with other windows (programs) and fill out the form opened in the browser?
• Are there libraries?
• What should I study (give a link)!?

Answer 1

Grab is a simple and clear way.
Selenium - using the browser.
If there is JS in the forms, then the second option will do.
Recently, it was necessary to parse certain information from a page that was loaded using JavaScript. Selenium helped, PhantomJS was indicated by the browser.

Answer 2

Selenium Webdriver
Here is the documentation page. But in general, and Google to help.
docs.seleniumhq.org/docs