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Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
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Showing 3211–3240 of 3640 results
- SpotifyMediumBackend EngineerHow You Use AI Tools as an Engineer and Drive Their Adoption on Your Team
A Spotify behavioral question in two parts: how you use AI tools in your engineering work and side projects, and how you have pushed for AI adoption on your team. It tests judgment about AI output, verification habits, data safety, and influencing teammates.
Behavioral & LeadershipOnsite - SpotifyMediumMachine Learning EngineerJoin Tables and Rank Users
This question evaluates proficiency in SQL and data-engineering skills—specifically joins, aggregation and ranking via window functions, event deduplication, and query performance considerations across analytics tables.
Coding & AlgorithmsOnsite - SpotifyMediumBackend EngineerOn-Call Case Study: Debugging a Misbehaving Production Server
A Spotify on-call case study: as the engineer paged about a misbehaving production server, investigate by asking for metrics, logs and command output. It tests triage, impact assessment, systematic host and service diagnostics, mitigation trade-offs and incident follow-through.
Software Engineering FundamentalsOnsite - SpotifyHardMachine Learning EngineerPredict Next-Week Streaming Engagement at Event Scale
This question tests the ability to design an end-to-end ML system for user retention prediction, focusing on feature engineering, model scalability for massive user bases, and real-time inference latency.
ML System DesignOnsiteSystem DesignMLOpsRecommendation Systems - SpotifyMediumBackend EngineerVisit-Pattern Counter: Multi-Input Runtime Analysis and Production Hardening
A Spotify backend coding follow-up: for a function that finds the three-website visit pattern followed by the most distinct users, analyze time and memory using separate input dimensions such as records, users, longest per-user history and distinct sites. It also asks which functional and style changes the code needs before it ships in production.
Software Engineering FundamentalsOnsite - Sprinter HealthMediumSoftware EngineerDesign a scalable game app store
This question evaluates a candidate's ability to design a scalable backend system, covering competencies in system architecture, data modeling, distributed services, media asset delivery, secure transactional flows, and operational trade-offs around scalability, availability, and consistency.
System DesignOnsite - SquareMediumSoftware EngineerBuild a Trust-Aware BIN Database
Build an in-memory card-prefix database that resolves brand and card type independently across overlapping writes. Practice combining longest-prefix matching with trust and recency rules while preserving omitted fields and supporting heavy lookup traffic.
Coding & AlgorithmsOnsite - SquareMediumSoftware EngineerExplain an AI-Assisted Engineering Workflow You Can Defend
Use one real project to explain the path from ambiguous requirements through design, implementation, launch, and maintenance, with AI assistance treated as a bounded tool. Show stakeholder alignment, decision trade-offs, independent verification, rejected output, and post-launch learning.
Behavioral & LeadershipOnsite - SquareMediumSoftware EngineerLead a High-Leverage Project in a Regulated Legacy System
Prepare a senior project deep dive spanning business leverage, personal ownership, delegation, architecture, migration, performance, reliability, and cost. Extend the analysis to regulated legacy systems where reconciliation, auditability, controlled rollout, and silent correctness failures matter.
Behavioral & LeadershipOnsite - SquarepointEasySoftware EngineerApply Insert, Update, and Remove Operations to a Keyed Store
Implement an in-memory key-value store processor that executes insert, update, and remove commands with strict handling for missing or duplicate keys, returning the final state in deterministic order.
Coding & AlgorithmsOnsiteHash MapDesignString - SquarepointEasySoftware EngineerExplain Database Indexes and Why Every Column Should Not Be Indexed
Explain database indexes, selective lookups, write overhead, composite keys, and why indexing every column can hurt a mixed workload.
Software Engineering FundamentalsOnsite - SquarepointEasySoftware EngineerExplain Python Immutability, Tuples, Hash Tables, and Caller-Level Errors
Practice Python tuple rebinding, shallow immutability, hash-table insertion and complexity, and caller-level handling of record-operation errors.
Software Engineering FundamentalsOnsite - StackAdaptMediumMachine Learning EngineerCamel and Bananas: Maximize Bananas Delivered Across the Desert
Classic camel-and-bananas brainteaser: a camel that carries at most 1,000 bananas and eats one per kilometer must move 3,000 bananas to a market 1,000 km away. Find the maximum number that can arrive, testing piecewise cost reasoning, depot planning, and a proof of optimality.
Statistics & MathOnsite - StackAdaptMediumMachine Learning EngineerFind the Flaws in an End-to-End ML Pipeline Case Study Report
Review a condensed end-to-end machine learning case study, from its goal and labels through normalization, evaluation, and deployment, and point out what is wrong with it. Tests systematic pipeline review, reasoning about what data each step uses, and ranking problems by how much they undermine the conclusions.
Machine LearningOnsite - StackAdaptMediumMachine Learning EngineerRebuild a Binary Tree From Preorder and Inorder Sequences, Returned in Level Order
Reconstruct a binary tree with distinct values from its preorder and inorder traversals and return it in level-order form with null markers. Tests how the two traversal orders pin down structure, careful index bookkeeping, and efficient handling of deep, skewed trees.
Coding & AlgorithmsOnsite - StackAdaptMediumMachine Learning EngineerReservoir Sampling: Uniform k-of-n Sample From a Stream of Unknown Length
Design a one-pass algorithm that keeps a uniform random sample of k items from a stream whose length is unknown in advance, using memory proportional to k. Tests the replacement rule, an inductive proof that every item is kept with equal probability, complexity, and edge cases.
Statistics & MathOnsite - Startups.ComMediumMachine Learning EngineerDebug and scale a PyTorch training loop
This question evaluates debugging and performance engineering skills for deep learning training pipelines, including diagnosing convergence and instability issues in PyTorch, scaling training with Fully Sharded Data Parallel (FSDP), designing sparse gradient all-reduce communication patterns, and judging when to implement custom CUDA/Triton kernels. Commonly asked for Machine Learning Engineer roles within the Software Engineering Fundamentals domain, it assesses both conceptual understanding of numerical stability and distributed systems and practical application skills in configuring multi-GPU training, communication trade-offs, and low-level performance and correctness validation.
Software Engineering FundamentalsOnsite - Startups.ComMediumMachine Learning EngineerDesign efficient Transformer inference with KV cache
This question evaluates an engineer's competency in ML systems engineering, specifically understanding of decoder-only Transformer inference, KV cache semantics and which tensors are cached per layer, attention mechanics, memory layout, and correctness under branching and long-context workloads.
ML System DesignOnsite - Startups.ComMediumMachine Learning EngineerImplement common neural network layers in PyTorch
This question evaluates proficiency in implementing core neural-network primitives (ReLU, numerically-stable Softmax, LayerNorm, BatchNorm with running statistics, and RMSNorm), numerical stability and normalization concepts, and understanding of autograd-compatible tensor operations.
Coding & AlgorithmsOnsite - StripeMediumSoftware EngineerAssign Reviewers from Changed Files
This question evaluates proficiency with version control diffs, repository library APIs, file I/O and CSV parsing, and data aggregation to map changed files to their owners.
Coding & AlgorithmsOnsite - StripeMediumSoftware EngineerBuild an Account Transfer Ledger
Design and implement an in-memory account ledger that supports deposits, transfers, and platform-backed lending with automatic debt repayment.
Coding & AlgorithmsOnsitedesignhash-tablestate-machine - StripeMediumFrontend EngineerBuild and Optimize a React Interface Against an Undocumented API
Tests your ability to inspect an opaque or changing backend endpoint, build a resilient React component with typed normalization and client-side caching, and handle edge cases gracefully.
Software Engineering FundamentalsOnsitereacttypescriptcaching - StripeMediumData ScientistChoose target customers and define success metrics
This question tests the ability to design an experimental rollout strategy for a new financial product, requiring a balance between revenue growth, risk mitigation, and statistical validity.
Analytics & ExperimentationOnsiteExperimentationRisk ModelingProduct Analytics - StripeMediumSoftware EngineerCompute account balances with rejection and overdraft
This question evaluates stateful transaction processing and aggregation skills, including per-(account,currency) balance maintenance, timestamp-based ordering, rejection rules, and overdraft coverage via a platform account.
Coding & AlgorithmsOnsite - StripeMediumSoftware EngineerCompute balances with transaction fees and rejections
This problem tests the ability to manage stateful financial records while enforcing conditional logic, fee structures, and balance validation.
Coding & AlgorithmsOnsiteHash MapData ProcessingFinancial Logic - StripeMediumSoftware EngineerCompute currency conversions with graph algorithms
Stripe software-engineer onsite coding question: design data structures and algorithms to compute currency conversions from pairwise exchange rates. It tests modeling currencies as a weighted directed graph, chaining rates with BFS/DFS to answer queries (or -1 when unknown), supporting online updates and many queries efficiently, detecting contradictions and arbitrage in cycles, and computing all rates against a base via topological sort on a DAG, with time and space complexity analysis.
Coding & AlgorithmsOnsite - StripeMediumSoftware EngineerConnect JSON Coordinates Through a Documented Drawing API
Plan coordinate parsing and drawing-API integration with explicit geometry semantics, request mapping, error handling, and idempotent recovery.
Software Engineering FundamentalsOnsite - StripeMediumSoftware EngineerConvert bitmap into ASCII characters
This question evaluates skills in binary-to-text data representation, bitmap rendering, and efficient string and array manipulation for output formatting.
Coding & AlgorithmsOnsite - StripeHardSoftware EngineerDebug Validation Error Aggregation
Tests the ability to traverse nested validation error trees and normalize them into a flattened dictionary mapping dotted-path keys to aggregated lists of error messages.
Software Engineering FundamentalsOnsiteTree TraversalRecursionData Structures - StripeMediumSoftware EngineerDesign a Count-Metrics Monitoring Platform
Design a scalable count-metrics monitoring and alerting platform capable of tracking real-time event counts and rates, grouping by dimensional labels, handling duplicate/late events, and enforcing cardinality limits.
System DesignOnsiteDistributed SystemsObservabilityStream Processing
Spotify
Square
Squarepoint
StackAdapt
Stripe