We use Oban for background job processing, and we couldn’t be happier. It’s extremely easy to setup as it uses Postgres as its backend, so there is no need to add any external dependencies like Redis.It’s also very powerful and feature-rich. We’re currently using it for sending notifications, but we’ll soon start replacing other custom-made GenServer based background jobs, thus simplifying our codebase.We heavily use HTTPoison for interacting with external services. Elixir doesn’t have as many libraries as Ruby, so there’s not always a mature client library for every service. HTTPoison allows us to quickly build a client for any service – we can have the endpoints we need put together in a module in a few minutes.We also use Trans to power our multi-language capabilities, which has made our life easier and our customers very happy since they can seamlessly communicate in multiple languages.