HubSpot - Cambridge/Boston, MA
<a href="http://hubs.ly/y0zbwS0" >
HubSpot is a great place to work with a great culture of getting things done and delighting our customers.  HubSpot loves investing in Engineering as a way to build a world-class product.
On the front-end, we use technologies like CoffeeScript and React to create a wonderful experience for our users interacting with the system.
On the back-end, we use technologies like HBase, Kafka, MySQL, Elasticsearch, ZooKeeper, and Dropwizard.  If you haven't looked at Dropwizard, it's actually a really nice way to develop web services in Java: you can annotate paths like you would do in Python and Flask and just return a Java object that will be serialised into JSON for you by Jackson.
Engineering is organised into small teams (usually around 3 people) where you can have a big impact on the product.  We deploy hundreds of times per day and use GitHub Enterprise for SCM, Jenkins to build, and an internally developed open-source system built on top of Mesos called Singularity to deploy app instance containers.  Your changes won't be languishing in git waiting for a major release.  Because deploys are so painless, we're able to deploy small changes.
If Google's catch-phrase is "Don't be evil" ours is "use good judgement".  Check out our Culture Code for more information: <a href="http://www.culturecode.com" >.  Also take a look at our 2014 Year in Review if you're interested: <a href="http://hubs.ly/y0zbyd0" >.
Work schedules are flexible, though most engineers get in around 10am.  You get to make a meaningful difference in a product with loads of paying customers and a ton of traffic. Best of all, you get to work with loads of smart and fun people. That's the best thing about HubSpot: the people are great people that you can rely on, learn from, and have a great time getting things done with.
Ask HN: Who is hiring? (March 2015)