Slack Frontend Interview
What frontend candidates typically face at Slack — realtime messaging UI, coding, design, and prep. Composite/unofficial.
- interview-experience
- slack
Composite, unofficial guidance based on publicly shared candidate reports and common Slack (Salesforce) hiring patterns for frontend / client engineering. Processes vary by team and level — confirm with your recruiter. Not affiliated with Slack or Salesforce.
Typical loop
| Stage | Focus | Format |
|---|---|---|
| Recruiter | Role, level | Call |
| Technical screen | Coding | Shared editor |
| Onsite / virtual loop | Coding, system/UI design, behavioral | 4–5 interviews |
| Decision | Packet | Internal |
Slack is a realtime, keyboard-heavy, long-session SPA. Design answers should include presence, ordering, and performance of long message histories.
Coding rounds
Medium(+) DSA; JS/TS common:
- Strings, arrays, hashes
- Graphs/trees
- Practical async problems
Practice: Valid Parentheses, LRU Cache, Merge Intervals, Number of Islands, Binary Search.
Frontend focus
- Virtualized message lists
- Composer + shortcuts
- Unread markers and scroll anchoring
- Typeahead for emoji/people/channels (Autocomplete)
- Accessibility for dense productivity UI
System design
- Channel message view with history pagination
- Thread panel
- Global search
- Notification preferences
Discuss: websocket reconnect, message idempotency/ordering at UI layer, cache of channels, keyboard UX, memory over multi-day sessions.
Related: Design a News Feed, Infinite Scroll Feed.
Preparation plan (6–8 weeks)
- JS async + React perf
- DSA
- Chat-list machine coding
- Realtime design outlines
- Mocks
Takeaways
- Realtime + virtualization + keyboard craft differentiate candidates.
- Still clear algorithms.
- Slack may share process elements with Salesforce — verify.