Top 19
Prep plan
Updated weekly · Last refresh Aug 30

Substack Software Engineer Interview Questions

The questions to prepare for a Substack Software Engineer interview. Questions from real interview reports rank first. Updated weekly.

19questions
~3htotal time
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1
CodingStart here. 5 questions · ~46 min
Key-Value Store ImplementationMedium
Practice

Implement Substack's in-memory key value store with separate chaining for average O(1) updates, lookups, and deletes.

Data StructuresSubstack
Range Updates Data StructureHard
Recently asked

Tests ability to design efficient data structures for range operations.

efficiencySubstack
Non-Linear Range Set StructureHard
Recently asked

Tests ability to implement efficient range update and query data structures.

efficiencySubstack
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2
System Design7 questions · ~64 min
Email Throughput vs Real-TimeHard
Recently asked

Evaluates system design trade-offs for throughput, latency, and reliability.

Trade-offsdata processingSubstack
Caching and PrecomputationMedium
Recently asked

Evaluates ability to improve performance using caching strategies and precomputation.

cachingoptimizationSubstack
Varying Loads and Time-Sensitive EventsMedium
Recently asked

Evaluates design decisions for scalability, latency, and event handling under load.

system designSubstack
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3
Behavioral & Leadership6 questions · ~55 min
React Class Components ConsiderationsMedium
Recently asked

Assesses understanding of React component architecture and lifecycle trade-offs.

reactSubstack
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4
More topics1 question · ~9 min
SQL for Subscription TransitionsMedium
Recently asked

Tests ability to model subscription state transitions and data integrity in SQL.

sqlSubstack
Hands-on SQL practiceWrite and run real queries in the editor. 3 drills · ~30 min
The finish line: interview-readyComplete all 19 questions plus 3 hands-on drills to finish this plan.