The interview takes far too long at between 8 to 13 hours to complete. This is disrespectful to applicants and is the reason I withdrew my application once I had another offer.
First is a 1 hour phone screen with the recruiter. It's called a phone screen but they come with questions from the hiring manager, so it's basically a light interview. You can be cancelled from the process here.
Then there is a 1 hour interview with the hiring manager.
Then there is a 2 - 6 hour take home assignment. The time to complete varies on what assignment you get, how proficient you are in the given languages, etc.
Then there is a 4.5 hour in person assessment.
There is no need for interviews to be so long. Interviews with Amazon and Google only take 6 hours and are heavily criticized for being too long. There is no reason to have an interview process longer then Amazon and Google.
Interview questions [1]
Question 1
I withdrew early so was only asked questions about my prior experience, why slack, etc.
I applied online. The process took 4 weeks. I interviewed at Slack (Seattle, WA) in Aug 2025
Interview
The worst interview experience I ever had. The recruiter reached out to me for this position and after recruiter call, I had one Hiring manager call and I had to follow up couple of days later and was responded in a minute about next steps i.e. Take home Code Review. The take home assignment is a complete waste of your time, they allow you 24 hours and even if you followed all good code review practices, you have no idea about the interviewer is expecting. Then comes the most frustrating part, until this time the recruiter was very responsive and providing detailed answers for queries but after this round, no response even after I had followed up twice. I was ghosted without even a result. At least in normal interviews you can get a sense of whether interviewer was happy with you. Giving take home test and wasting 3-4 hours on their buggy code is useless.
Interview questions [1]
Question 1
How would you debug if a service starts delaying responses suddenly.
I applied through an employee referral. The process took 3 weeks. I interviewed at Slack in Aug 2025
Interview
Long interview process. Recruiter screen, manager screen, code review take home (I spent 1.5 hours). Then a final loop with system design, coding (1.5 hours), and 2 behaviorals. The managers I talked to were great, but none of the engineers seemed engaged at all or like they wanted to be there. After the final loop (which I thought went well) I was ghosted by the recruiter, he didn't even respond after I followed up a couple times asking for status. It's unacceptable to not even get a generic rejection email considering all the time I put into this interview process. Complete waste of time.
Interview questions [1]
Question 1
Coding - download real codebase with a Slack-like chat app using Sqlite DB. Had a list of prompts to add a feature (private channels)
System design - Design system to injest commands/keywords given in Slack messages, call 3rd party APIs based on them
Behavioral - mostly standard questions, also asked some vague open ended technical questions like "how would you think about the API for user search suggestions in Slack"
I applied through a recruiter. The process took 4 weeks. I interviewed at Slack (Atlanta, GA) in Nov 2024
Interview
First Round: Recruiter Screening
Second Round: Chat with Staff Engineer
Third Round: Technical Challenge; build a mini-app
Fourth Round: 4 separate interviews with the team, 2 of which were system design