Backend Engineer Interview Questions

Showing 1–5 of 5 results

• InstacartMedium·Backend Engineer
  Debug Metrics Computed Before Filtering

  Debug a metrics endpoint whose summary is calculated before user filters are applied even though its rows are filtered correctly. Trace the data lineage, aggregate over the full matched population before pagination, preserve security scoping, and add unit and endpoint regression tests.

  Software Engineering FundamentalsOnline Assessment
• InstacartMedium·Backend Engineer
  Design Idempotent Due-Date and Hold Notifications

  Design idempotent library notifications for upcoming and current due dates plus FIFO hold availability. Use stable business-event identities, transactional scheduling, atomic recipient claims, state rechecks, retries, reconciliation, and clear frontend distinctions among holds, offers, and checkouts.

  System DesignOnline Assessment
• InstacartMedium·Backend Engineer
  Fix the Broken Search Filter in a Book Catalog API

  This problem tests your ability to sanitize inputs and implement robust filtering logic on a collection of structured objects using multiple criteria.

  Coding & AlgorithmsOnline AssessmentFilteringStringsBackend
• TTargetMedium·Backend Engineer
  Find the Closest Candidate String by Edit Distance

  This problem tests the implementation of the Levenshtein distance algorithm (Edit Distance) and the ability to manage tie-breaking logic when comparing multiple strings against a query.

  Coding & AlgorithmsOnline AssessmentDynamic ProgrammingStringsOptimization
• TTargetMedium·Backend Engineer
  Implement a Synchronized First-Available Seat Allocator

  This problem tests your ability to design a thread-safe allocator that manages a finite resource pool under high concurrency, focusing on atomic updates and race condition prevention.

  Software Engineering FundamentalsOnline AssessmentConcurrencyAtomic OperationsThread Safety