Crowdstrike·Software Engineer·Onsite - System Design / Architecture
Apr 2026
Crowdstrike system design round, clearly aimed at senior-level folks. The whole session was one big question about building a file upload and scanning platform, and they wanted you to go deep on basically everything: storage, async pipelines, security, scale. Felt like they were stress-testing how far you could go before you started hand-waving.
- Design a file upload and scanning system where users upload files, those files get scanned (for malware, sensitive content, or validity), and a report is delivered back to the user.
- How would you handle the upload side for very large files, including resumable uploads and integration with object storage?
- Walk through the asynchronous scan pipeline. How do workers pick up jobs, and how do you manage a pool of pluggable scanners with different latency profiles?
- How do you deliver scan results back to users? Cover polling, webhooks, and email notifications.
- How do you handle retries and ensure idempotency when parts of the pipeline fail?
- What are the security considerations: authentication, encryption, and quarantining files that fail malware scans?
- How does this system scale as upload volume grows and as scan latency increases?
“This is a big one.” The rest of the author's notes on Software Engineer interview at Crowdstrike, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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