In Uploadcare we like to write internal documentation and instructions for all occasions. We used Confluence before, but strong and very slow UI fall us to frustration. We start to research alternative and met slite. The ability to quickly create notes and search, great onboarding, the familiar interface in Slack style, useful shortcuts, nice code snippets, support of Markdown. Now writing instructions and team notes have become much more pleasant.
We use AWS Lambda mainly in combination with Amazon S3 to resize the images that our clients upload in our platform. Working with real estate agents means lots and lots of photos that need to be resized when they are on a website so that the visitors of our clients can navigate on a website that it's fast and beautiful at the same time.
We make sure to implement only the functionalities that are specific to our business domain (Beauty & Wellness) & use other services for functionalities we find generic or secondary (they do not make us stand out). We've picked the most stable & popular ones we could find for such purposes: Google Maps (for salon location maps), Mandrill (sending mail notifications), Twilio (sending SMS notifications) or Braintree (for payments).
If jQuery or vanilla are the only two options available, then use the library that's available when its features will avoid having to reinvent wheels. Look at what jQuery offers, and look at the things you want to do. If a handmade solution doesn't require a lot of extra effort, then don't bother.
Most of CircleCI is written in Clojure and it has been this way since almost the beginning. Early development included Rails, but by the time that CircleCI was released to the public, it was written entirely in Clojure. Clojure is still at our platform’s core. It helps having a common language across much of our stack to allow for our engineers to move between layers of the stack without much overhead.