This is one of the key tools I can't leave out when I'm working on a project, basically it is mandatory for me to use it on my Ruby on Rails projects. I think the price is a little expensive for a "Solo plan" but if you can get your client to pay, it's definitely worth it. You or the future developers that will continue with the project will thank you!

I've been using Heroku for 3 years now, they have grown super fast and each time they're improving their services. What I really like the most is how easily you can show to your client the advances on you project, it would take you maximum 15 minutes to configure two environments (Staging/Production). It is simply essential and fantastic!

I had the opportunity to integrate Braintree as a new gateway on a project I worked on last year (RoR project), the change from PayPal to Braintree was smooth and now it's really easy to maintain. The documentation for the API was super easy to follow. Really enjoyed using Braintree.

I really like HipChat, not only because it's available on whatever "machine/device" you use but it has a ton of add-ons that you can integrate in you chat room that keep you and your team constantly aware of what's happening with your business.

It's incredible how much this service has increased my productivity when it comes to testing new features in multiple browsers. And not only multiple browsers, multiple operating systems as well! And really LOVE that you can run it locally.

Twilio is by far the most complete solution for SMS, its API is extremely well structured. And its integration with rails is pretty straight forward.