Candidates report Zscaler software engineer interviews that pair medium-level DSA with operating systems, networking and OOP fundamentals, often starting with an online assessment and ending with an HR or managerial conversation.
$138K
Avg. Base Comp
$215K
Avg. Total Comp
Not reported
Typical Rounds
Not reported
Process Length
Candidates who interviewed for Zscaler software engineer roles describe a loop that goes well beyond algorithm practice. Reports mention medium-level DSA across graphs, dynamic programming and trees. They also mention prompts such as a min stack and an LRU cache in O(1), and implementing a linked list from scratch with OOP principles. The same accounts also stress operating systems and computer networking fundamentals.
The fundamentals questions reported are specific: round robin scheduling, IPv4 headers, collision avoidance, DNS, the TCP three-way handshake, and protocols such as SSH and HTTPS, plus basic OOP concepts. One candidate also faced database-oriented design prompts, including TTL, loading CSV data into a database, and rate limiting database queries. Rehearse explaining concepts in plain English with trade-offs rather than reciting definitions.
Language expectations can matter. One candidate's coding test allowed any common language. Another had a backend section limited to C, C++, Java or Golang and a separate Python-only section. Check with your recruiter which language your team expects.
The format varies by candidate. Reports include a multi-question coding test, a pre-interview session about the company, a 75-minute technical interview, and a final HR or managerial round. One candidate described three technical interviews on site followed by a round with the R&D director and HR. Outcomes were mixed: some candidates received offers and others did not. One candidate said communication after the final round was slow and needed follow-up, so plan to check in with your recruiter. Treat the round order as typical rather than fixed, since it differs between candidates.
Synthesized from 21 candidate reports by our editorial team.
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Real interview reports from people who went through the Zscaler process.
I didn't get an offer, but the on-site loop taught me more about where to focus than any prep guide did. It had two technical parts. The first was designing an LRU cache, and the interviewer wanted it in high-level pseudo-code rather than a full implementation. I had to explain how I'd track recency, which operations needed to stay fast, and how the pieces fit together, without getting pulled into language-specific syntax.
The second part was where the conversation really happened. The scenario was a service that handles synchronous queries from multiple tenants, and each query hits a database. The database can run only 10 queries at a time, and it can't be replicated, sharded, or cached. On top of that, tenants send requests at different rates, so one busy tenant can crowd out the others. My task was to optimize the system within those hard constraints.
The follow-ups moved into queues, topics and partitions, retries, and trade-offs. The interviewer pushed on how I'd decouple the synchronous callers from the database, how I'd keep a heavy tenant from blocking everyone else, and what retries would do to a database that's already at its concurrency ceiling. These questions weren't really about naming a technology. They were about justifying each choice under a fixed limit.
Looking back, I'd spend less time polishing the LRU details and more time stating my assumptions about the database cap and tenant fairness before proposing anything, since that's where the discussion actually went.
Prep tip from this candidate
Practice designing under a hard concurrency cap of 10 database queries with uneven tenant request rates, and be ready to defend your choices of queues, partitions, and retry behavior. Spend as much prep time on that scenario as on the LRU cache.
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Topics based on recent interview experiences.
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| String Subsequence | |
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| LRU Cache 1 | |
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| Top Three Salaries | |
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| Customer Orders | |
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| Comments Histogram | |
| Raining in Seattle | |
| Minimum Change | |
| Find the First Non-Repeating Character in a String | |
| Bagging vs Boosting | |
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Synthesized from candidate reports. Individual experiences may vary.
Candidates report resume shortlisting followed by an online coding test. One described 3-4 medium-to-hard questions spanning graphs, dynamic programming and trees. Another described two 90-minute sections, one backend-focused and one Python-only. Expect the format to vary by role and team.
Some candidates report an early conversation before the technical loop. One described a Zoom chat with a team lead, and another described sessions covering Zscaler's journey and the interview flow. Use it to ask about the expected language and round structure, since reports vary.
Candidates typically describe medium-level DSA mixed with fundamentals. Reported topics include LRU cache, min stack, a linked list built with OOP principles, round robin scheduling, IPv4 headers, DNS, the three-way handshake and OOP concepts. One candidate reported a 75-minute round; another reported three on-site technical interviews.
One candidate reported database-oriented design prompts rather than classic system design, including TTL, loading CSV data into a database and rate limiting database queries. Prepare to talk through trade-offs, though not every loop includes this.
Candidates report a final HR or managerial conversation covering past situations, challenges, projects and motivation for joining. One described a round with the R&D director and HR. One candidate reported slow communication afterward, so following up with your recruiter may be necessary.
