Just finished my DoorDash SWE onsite last month. L4 / mid-senior mobile track. Got the offer. Before the memory fades I want to write the prep guide I wish existed when I started.
Spoiler: I wasted probably 60% of my prep time on the wrong stuff.
What the loop actually looks like (2026)
For mobile/iOS at L4: recruiter screen, one technical phone screen (45 min, coding), then onsite with four rounds. Mine were: two coding, one system design, one behavioral. Behavioral was with a senior EM not my potential direct manager, which I didn't expect.
Total time from first recruiter message to offer: 5 weeks. That's fast compared to what I've heard from friends doing the loop 18 months ago.
The coding rounds
Both were on CoderPad. Problems were medium-difficulty, graph and sliding window. Nothing that would stump someone who's been grinding consistently. The trick: they watch you think out loud the whole time. I've done interviews where you can sit quietly and think. Not here. If you go quiet for more than 30 seconds the interviewer gets visibly uncomfortable. Practice talking while coding, it's a separate skill from solving.
System design
For mobile they asked about designing an offline-capable order tracking system. Pretty relevant to the actual product. Know your local storage options, conflict resolution when reconnecting, how you'd handle a dropped connection mid-delivery. The interviewer pushed back on my first approach and wanted to see how I handled the revision. That's the real test.
What I'd change about my prep
I spent three weeks on LeetCode hard problems. Should have spent those three weeks doing mock interviews out loud. The hard problems didn't come up. Thinking out loud under someone watching you did.
I also ignored the behavioral prep almost entirely. I figured six years of experience would carry me through. The behavioral round had nuanced questions about handling cross-functional conflict and prioritizing eng debt vs. product work. Have actual prepared stories for those, not vibes.
The last thing: read about DoorDash's actual engineering challenges. They publish eng blog posts. The system design round is way more grounded if you understand their real-world scale constraints.