Sr. Software Engineer, Realtime Services, Core Infrastructure


Slack enables people all over the world to communicate and collaborate together. Teams of all scales — from the world’s largest public companies to the smallest of startups — use Slack to get work done, so we take performance and reliability very seriously. A taste of our scale:

  • During the week, our users spend over a billion minutes a day active in our product.
  • At peak usage, a million messages a minute passed through Slack.
  • Every day we see over 15 million simultaneously connected users


For millions of people, Slack is the primary communication tool they use at work all day long. They expect it to be exceptionally reliable and fast, all the time.

About our team

The Realtime Services Team is a small team making a huge impact. We rapidly iterate and work closely with other teams in engineering to ensure we build resilient systems that scale. We are ambitious, independent, and pragmatic. We build and maintain the messaging layer at Slack to ensure that all messages are routed to users as fast and as reliably as possibly. Our services are written in Java and hosted on AWS infrastructure. We build and deploy using Jenkins, and we provision infrastructure using Chef and Terraform. We are a globally distributed team with members in the Bay Area, Canada, and Tahoe, and we’ve been using Slack heavily to collaborate on our work even before it became THE thing to do. 


We know we’ve done our jobs well when none of our users think about us. We don’t typically ship shiny, new, user-facing features, but rather ensure our systems are incredibly performant, highly available, reliable, secure and scalable. 


If you were to join the team, here the types of things you would do over the course of a typical week:

  • Design, build, ship and maintain the messaging infrastructure that is at the core of Slack
  • Collaborate with peers across Engineering  to triage bugs and troubleshoot complex production issues across the stack, especially with respect to performance or scale.
  • Whiteboard a fix to a reliability problem — and then make it happen!
  • Write, review, or provide feedback on a technical design proposal


You may be a fit for this role if you:

  • Have a Bachelor's degree in Computer Science, Engineering or related field, or equivalent training, fellowship, or work experience.
  • Possess strong Computer Science fundamentals: data structures, algorithms, programming languages, operating system, distributed systems, and information retrieval.
  • Been building large scale systems professionally for 5+ years and can point to things you’ve worked on.
  • Have experience building reliable and safe distributed systems and understand the trade-offs made when engineering a feature.
  • Have experience deploying and operating services in a Cloud environment.
  • Can jump into situations with few guardrails and make things better.
  • Write code that can be easily understood by others with an eye towards clarity and maintainability.
  • Are a very strong communicator. You’re excited to explain complex technical concepts and share your knowledge with different audiences.
  • Are curious how things work and when things break you are eager and able to help fix them.
  • Hold lawful permanent residency within the US


Realtime Services Team is a diverse and inclusive team that is building the future of Slack’s infrastructure. We are happy to help you learn what you need to know; we encourage and support each other’s growth and it’s not expected that you would have expertise across all of these areas from the beginning.


Come join us!


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