How do you measure the willingness to pay of users & the price sensitivity?

Hello all, As we are now growing, we are looking into monetizing our solution. We provide a platform for software developers and tech leads that helps streamline development workflows and automate team cooperation (keypup.io). On the developers market, there is a well known business model, which is fremium: essentially, the platform comes with a free-forever base offer, and then there are paid plans for some "advanced" or "premium" features. The question we have to tackle is 2-folds: 1 - How do you measure the willingness to pay of your users ahead of launching the monetization? Is there a tool you can use or what would be a good way to go about it? 2 - How do you measure the price sensitivity? Of course, there is always looking at what the competition or similar services do. But is there a way to "test" the market? Thanks in advance for your inputs!