Coding fluency
Implement an LRU cache. Explain your data structures, test capacity one, and walk through an eviction.
What a strong answer demonstrates
Correctness, edge cases, and time / space complexity.
Prepare for Slack with a focused mix of coding, design, and communication. Start with your job description and confirm the interview loop with your recruiter.
6 Question notes
6 Practice picks
1 Interview reports
5 Levels mapped
01 / MAKE YOUR NEXT SESSION COUNT
Your preparation, made concrete.
System design
Design a notification service. Clarify delivery guarantees, model the data, then handle retries and duplicate events.
What a strong answer demonstrates
Clear requirements, a working baseline, and explicit trade-offs.
Behavioral storytelling
Describe a technical decision you changed after receiving feedback. Explain your contribution and the outcome.
What a strong answer demonstrates
Specific actions, honest reflection, and measurable impact.
BEFORE YOU PRACTICE
Ask your recruiter.
Get the details that a generic company guide cannot know.
- Which team and level is this opening for, and what does success look like?
- What rounds, durations, and evaluation criteria should I prepare for?
- Which languages, tools, and AI assistance are permitted?
- Will design focus on frontend, backend, infrastructure, or another specialty?
- Are there accommodations or preparation materials I should request?
Slack practice problems
Company-linked challenges and related lessons from our library. Not a prediction of your interview.
Challenge
Difficulty 4/10
Max of Min Pairs
Challenge
Difficulty 4/10
Max Per Level
Challenge
Difficulty 6/10
Two Stack Queue
Challenge
Difficulty 4/10
Find the Intersection of Two Linked Lists
Challenge
Difficulty 8/10
Convert Number to Words
Challenge
Difficulty 3/10
Binary Tree Inorder Traversal
Questions candidates have reported
Aggregated from candidate submissions and public sources.
Q1
Write some code to get the number of tags on the any website given a url.
Q2
Review a pull request on github.
Q3
1 week take-home exercise: build a single page application image gallery, connecting to a public image api, and add lightbox functionality. make it performant and cross-browser compatible.
Q4
Create a twitter client architecture. must have persistent storage; explain that architecture.
Q5
Given a quick whiteboard mock of a web app, discuss how you would design and implement it.
Q6
Build a ui with javascript.
Engineering levels & compensation
Historical figures from existing records; date and location may be unspecified. Verify current ranges on Levels.fyi.
Level 1
Associate Engineer · G03
Not Available
Level 2
Engineer · G04
Not Available
Level 3
Senior Engineer · G05
Not Available
Level 4
Staff Engineer · G06
Not Available
Level 5
Senior Staff Engineer · G07
Not Available
Real interview experiences
1 report from candidates who interviewed at Slack.
What people at Slack say
Reviews originally posted on Glassdoor.
Strong executive leadership pointing the company in the right direction. Best culture I've experienced so far -- the people I work with are driven yet compassionate. We are expected to work hard and smart for 8 hours a day, then go home. Building a product that I use on a daily basis is exciting. Frequent reorganizations and process changes, not surprising for a fast-growing company but could be annoying. On certain teams, there's a lot of tribal knowledge that makes it difficult for a newcomer to start contributing right away. People can be too nice to the point where difficult topics are avoided.
Wonderful culture: humility, empathy and just plain good natured personalities abound. Having worked at many large, high profile internet companies the hardest thing to get used to is: yes, these people are also very very smart and talented.
Work with some of the brightest and diverse people in tech. A lot of the engineers at Slack were previously at Facebook, Google, etc. and helped build out those companies. Awesome perks, good, food, great snacks, amazing founders very transparent work place. The people at Slack are very emphatic and help you when you need it. Oh yeah, free weekly massages are pretty awesome. Tough deadlines can be stressful at times. Slack doesn't have catered food all days of the week. Some teams definitely have more work to do than others. If you're an engineer on one of these teams life can be a little stressful.
Lots of openness & communication from the executive,Good focus on work/life balance. Everyone leaves at a reasonable hour and you aren't expected to work outside of work hours. Everyone takes vacation. We get ownership of our projects and get a say in what we work on. Pay is decent but not the best you can get in the industry.
Growing pains, sometimes things are changing so fast that is hard to catch up with everything going on. Keep focus on fostering the culture that has helped succeed. Working on the same product you use on a daily basis is extremely motivating and fun. Lots of technical and professional challenges. Great opportunity to grow in your career. Great salaries and benefits.
Inside the workplace
About Slack
A day at Slack