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Top 50 Backend Engineer Interview Questions

The 50 most important questions to prepare for Backend Engineer interviews. Questions from real interview reports rank first. Updated daily.

50questions
~20htotal time
2,263companies covered
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1
SQL & Data ManipulationStart here. 12 questions · ~286 min
Checked vs Unchecked ExceptionsEasy
Practice
Recently asked

Compare checked and unchecked Java exceptions by retrieving their compile-time handling requirements and representative examples.

error handlingjavadatabase conceptsTThe CardWalmart Labs
SQL Query OptimizationMedium
Practice
Recently asked

Optimize a slow PostgreSQL query that aggregates completed transactions while preserving customers with no matching activity.

Performance Tuningdatabase optimizationindexesDDroisysCapgeminiNomura
Second Highest Trader SalaryEasy
Practice
Recently asked

Find the second highest distinct salary from a single table using basic PostgreSQL ordering and limiting.

SubqueriesRankingSortingeClinicalWorksNNeenOpal CanadaInformatica
SQL vs NoSQL DifferencesEasy
Practice
Recently asked

Query a comparison table to present the key structural and operational differences between SQL and NoSQL databases.

nosqlJoinsData WranglingCogitoRamsey SolutionsIInnovaccer
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2
Coding38 questions · ~904 min
Maximum Sum Contiguous SubarrayEasy
Practice
Recently asked

Use Kadane's algorithm to find the contiguous subarray with the largest sum in linear time.

Dynamic ProgrammingArraysGreedyMetaPublicis GroupeSmbc Global Foundation
Maintainable and Scalable CodeMedium
Practice
Recently asked

Implement a modular top-k frequency algorithm that scales with input size and preserves deterministic tie ordering.

clean codecode qualityDynamic ProgrammingJohnson & JohnsonTwitchL3Harris Technologies
Longest Subarray Sum Equals KMedium
Practice
Recently asked

Find the longest contiguous subarray whose sum equals K using prefix sums and a hash map.

ArraysEloeloTikTokGroupon
Detect Cycle in Linked ListEasy
Practice
Recently asked

Use Floyd’s two-pointer algorithm to determine whether a singly linked list contains a cycle.

Hash TablesLinked ListsTwo PointersSigmoidAMD Construction GroupInformatica
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