Our stack Collaboration tools

Here's a list of technologies that we prefer to use based on this scale:

Experimental - We're still playing around with this, and we feel very optimistic about it. Try it out!
Recommended - We'd use this hotness on all projects if we can!
Good - It's still a good choice, but consider better solutions for newer projects.
Sunsetting - We maintain projects with these, but don't start new projects with this anymore.
Avoid - Our poor experience with this tell us to stay away unless absolutely necessary.

Project management

Jira

Jira is a project management tool that's flexible enough to accomode just about every project's needs. It's a great choice for managing sprints.

Trello

Trello is good for very small projects. However, consider Jira if you're going to do sprints—Trello's limited featureset can be difficult to scale with.

Pivotal Tracker

We've used Pivotal Tracker in the past, but we've come to outgrow many of its features. Jira is a more flexible choice for us.

Communication

Slack

We've been using Slack to facilitate our communication, both in-the-office and remote. It's an indispensable tool for our day-to-day work.