The interview process was as follows:

• Referred by a friend
• Recruiter contact (email)
• Recruiter phone call
• Engineer phone call (mostly conversational about the company)
• Take-home project (1 week for completion)
• Engineer phone call (more detailed questions about specific work)
• Onsite #1 (~4 hours)
• Onsite #2 (coffee with manager and director, more casual)
• Offer received within a few days of the last onsite.

The recruiter was great throughout the entire process. She kept me updated on Slack's expectations and was supportive and responsive the whole way. Overall, it was a positive experience.

Onsites at Slack are not traditional; you won't waste time balancing trees or desperately trying to recall Dijkstra's Algorithm. Instead, you'll tackle a challenging take-home project and answer high-level questions that genuinely assess your engineering skills.

1. Take-home Project

For the front-end project, I was given a skeleton in React and told to build upon it, given the provided instructions and product requirements. They estimated about 3 hours, but considering its importance for the pay/offer, I ended up spending a whole weekend on it, likely around 15 hours.

1. Onsite Interviews

I had four separate talks/interviews:

• I met with a Director of Engineering. The questions were casual and focused more on my career goals.
• Secondly, I talked with some FE engineers. We reviewed my project, discussing its pros, cons, and potential improvements. Afterwards, we had a high-level architecture discussion about creating a vaguely described web page.
• Thirdly, I spoke with more senior FE engineers. One asked me how I would build Slack from scratch. This was an obviously open-ended question, likely intended to gauge the depth of my product design knowledge and how far I would explore the concept.
• The last interview was more of a social/cultural fit assessment, where we discussed my working style and personal attributes.