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Discord interview notes, page 3 of 4

Mid-sized

Most of these Discord write-ups come from Software Engineers (35), then Product Managers (3) and Backend Engineers (1). The most reported rounds are the technical phone screen (23), the system design round (8), the recruiter screen (3) and the behavioral / leadership round (2).

40 interview notes · updated Jul 2026

Discord·Software Engineer·Onsite - System Design / Architecture

May 2026
Discord system design round for what felt like a senior-to-staff level engineering role. The whole thing was one big question about building a Slack-like messaging system, but they made it clear upfront that the real test was in the follow-up rabbit holes on indexing, storage choices, and fan-out. Walked out not totally sure how I did.
  • Design a Slack-style messaging platform supporting workspaces, public and private channels, DMs, threaded messages, mentions, search, presence indicators, and notifications.
  • How would you index messages to support fast channel scrolling, full-text search, and unread counts?
  • Walk through your database choice for storing messages: relational, NoSQL, or a log-plus-KV split. How would you partition by workspace or channel?
  • Describe the fan-out path for a sent message: how does it reach all channel members, including offline users and mobile push, and how do unread counts get updated along the way?

“The surface area is massive so I tried to scope it fast and pick a few pillars to go deep on.”

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Discord·Software Engineer·Onsite - System Design / Architecture

Jun 2026
System design round at Discord for a software engineer role. The prompt was to build a Discord-like TCP chat server from scratch, which felt a little meta. A lot of ground to cover in one question.
  • Design a Discord-like chat server that supports multiple concurrent clients over raw TCP, including slash commands, chat rooms, message history, reconnection, and persistence across server restarts.

“This is a big one.”

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Discord·Data Scientist·Technical Phone Screen

Jun 2026
Product DS interview at Discord with two case studies back to back. Both were experimentation-heavy and required thinking through metrics, randomization, and edge cases. Pretty involved for a single session.
  • How would you define a 'power user' or 'high-intent user' for a subscription notification targeting use case?
  • How would you design an experiment to test whether sending a subscription notification to high-intent users is beneficial?
  • If the subscription notification experiment succeeds, what should the team investigate next?
  • How would you run an A/B test for an autocomplete feature on the 'Add Friend' page in a mobile app?
  • What metrics would you use to evaluate whether the autocomplete feature on the 'Add Friend' page is working?

“This felt deceptively easy and I kind of fumbled it.”

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Discord·Software Engineer·Technical Phone Screen

Jun 2026
Discord SWE interview round where they pulled up PuTTY live and walked through AI-generated code I'd written earlier. Less about coding from scratch and more about defending your choices, which I was not fully prepared for.
  • Why did you write your AI prompt the way you did?
  • Are the libraries the AI selected appropriate for this use case, and why or why not?
  • Is the extra functionality the AI added beyond what you asked for actually useful, or is it unnecessary?
  • How would you go about testing this code?
  • If you needed to add a new feature, how would you prompt the AI to write it and how would you verify the result?

“This one tripped me up more than I expected.”

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Discord·Backend Engineer·Onsite - System Design / Architecture

Jun 2026
Discord system design round, deep dive into distributed replication. They wanted a real implementation-level discussion, not just hand-waving at Raft. Harder than I expected and I definitely left some things on the table around split-brain prevention.
  • Design a leader-follower replication system similar to what etcd or Redis uses. Cover leader election, log replication, consistency semantics, failure detection, follower catch-up, split-brain prevention, and read paths. Show enough of the data plane to demonstrate writes propagating from leader to follower and surviving a leader failover.

“I went with Redis-style async replication because I could actually defend it, and pivoted to Raft semantics when they pushed on consistency guarantees.”

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Discord·Software Engineer·Technical Phone Screen

Jun 2026
Discord technical screen for a software engineer role, basically one meaty coding problem about stream processing and session detection. No behavioral stuff, just the problem and a lot of follow-up edge cases.
  • You're building a backend component that reads a continuous stream of newline-delimited JSON events, each representing a user sending a message to a channel. Define a user session as a sequence of events from the same user where no two consecutive events are more than 30 minutes apart. Implement something that parses this stream and emits a completed session record (with user ID, start/end timestamps, message count, and top channel) whenever a session can be finalized. The stream is potentially infinite, so you can't buffer everything.

“The 'infinite stream' constraint is what makes this non-trivial.”

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Discord·Software Engineer·Technical Phone Screen

Jun 2026
Discord SWE interview with a pretty gnarly systems question about race conditions. Not a lot of hand-holding, they wanted a real example not a textbook answer.
  • How do you debug race conditions in production? Walk through your strategy and describe a specific race condition you actually found and fixed.

“This one stung a little because I started with the generic answer (logging, thread sanitizers, etc.) and they just waited.”

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Discord·Software Engineer·Technical Phone Screen

Jun 2026
Discord data engineering interview with a SQL-heavy technical screen. One main problem covering multi-table aggregation, not too much else to report.
  • Given tables for servers, server views, server joins, and messages, write a SQL query that returns one row per server with the total all-time count of views, joins, and messages. How do you handle servers that have zero events in any of those categories?

“This one took me a minute to settle on an approach.”

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Discord·Software Engineer·Technical Phone Screen

Jun 2026
Discord SWE interview with a question focused on operational experience. Pretty specific and not the kind of thing you can bluff your way through if you haven't actually been on-call before.
  • Do you have on-call experience? Walk through the rotations you've been part of, the kinds of incidents you've handled, the runbooks and tooling your team used, and a specific incident you either led or learned something meaningful from.

“This question has a lot of parts and it's easy to just list things without actually saying anything.”

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Discord·Software Engineer·Onsite - Coding / Algorithms

Jun 2026
Discord SWE interview where I prepped the wrong thing entirely. The coding round was way more hands-on than I expected, basically pair programming a distributed systems problem from scratch with the interviewer sitting next to you (virtually) the whole time.
  • Implement a leader-follower distributed system locally. Nodes should know who the current leader is, support new nodes joining, and handle automatic failover with leader re-election when the leader goes down.

“I had spent a solid chunk of prep time on a chat server design I'd seen floating around, so when this came up I had to context-switch pretty fast.”

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