The Interview Loop
Recruiter Screen (30 min)
Standard fit check, behavioral questions, and resume overview.
Technical Loop (3-4 Rounds)
Deep dive into domain knowledge, coding, and system design.
Interview Question Bank
Software Engineer
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Behavioral
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medium
Tell me about a time you had to 'Act Like an Owner' and take over a failing project or a project without clear leadership.
#Ownership
#Leadership
#Initiative
Software Engineer
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Behavioral
•
medium
Describe a time you had a disagreement with a colleague or manager on a technical design. How did you resolve it?
#Clear Communication
#Conflict Resolution
#Collaboration
Software Engineer
•
Behavioral
•
medium
Tell me about a time you had to learn a new technology or domain completely from scratch under a tight deadline.
#Continuous Learning
#Adaptability
#Problem Solving
Software Engineer
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Behavioral
•
medium
Describe a production incident you caused or were heavily involved in resolving. What was the post-mortem?
#Accountability
#System Reliability
#Learning from Failure
Software Engineer
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Behavioral
•
easy
How do you prioritize your tasks when multiple projects seem to be high priority and deadlines are conflicting?
#Time Management
#Prioritization
#Communication
Software Engineer
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Behavioral
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medium
Tell me about a time you simplified a complex process, architecture, or piece of code. What was the impact?
#Simplification
#Code Quality
#Efficiency
Software Engineer
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Behavioral
•
medium
Describe a situation where you had to communicate a highly complex technical issue to a non-technical stakeholder.
#Clear Communication
#Empathy
#Stakeholder Management
Software Engineer
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Behavioral
•
medium
Coinbase values 'Clear Communication'. Tell me about a time you had a significant technical disagreement with a colleague. How did you resolve it?
#Conflict Resolution
#Communication
#Collaboration
Software Engineer
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Behavioral
•
medium
One of our core values is 'Act Like an Owner'. Describe a time you took ownership of a project or problem that was technically outside your job description.
#Ownership
#Leadership
#Initiative
Software Engineer
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Behavioral
•
easy
Tell me about a time you had to learn a new technology or programming language completely from scratch under a tight deadline.
#Adaptability
#Continuous Learning
Software Engineer
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Behavioral
•
medium
Give an example of a time you simplified a complex technical process or architecture. What was the impact?
#Simplification
#Process Improvement
#Execution
Software Engineer
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Behavioral
•
medium
Tell me about a technical project you worked on that failed or didn't meet expectations. What did you learn from it?
#Resilience
#Growth Mindset
#Accountability
Software Engineer
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Behavioral
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hard
Describe a situation where you had to make a critical architectural decision with incomplete information or high ambiguity.
#Ambiguity
#Decision Making
#Risk Management
Software Engineer
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Behavioral
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hard
Imagine you are on call and multiple critical systems (e.g., user logins and crypto withdrawals) start failing simultaneously. How do you prioritize and handle the situation?
#Incident Management
#Prioritization
#Under Pressure
Software Engineer
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Behavioral
•
medium
Tell me about a time you had to give difficult, constructive feedback to a peer or a manager.
#Feedback
#Communication
#Empathy
Software Engineer
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Coding
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hard
Implement an in-memory limit order book. It should support adding a buy/sell order, canceling an order, and executing trades when buy and sell prices match.
#Data Structures
#Priority Queue
#TreeMap
#Trading Systems
Software Engineer
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Coding
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medium
Given a list of cryptocurrency exchange rates (e.g., BTC-USD, ETH-BTC), write a function to find the best conversion rate between two specific currencies.
#Graphs
#BFS
#Dijkstra's Algorithm
#Math
Software Engineer
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Coding
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medium
Implement a Rate Limiter using the Token Bucket algorithm to restrict the number of API requests a user can make to a trading endpoint.
#Concurrency
#System Design Implementation
#Object-Oriented Design
Software Engineer
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Coding
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hard
Design an in-memory Key-Value store that supports nested transactions with BEGIN, COMMIT, and ROLLBACK operations.
#Data Structures
#State Management
#Stacks
#Hash Maps
Software Engineer
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Coding
•
medium
Parse a real-time stream of trade executions and calculate the Volume Weighted Average Price (VWAP) over a rolling 5-minute window.
#Sliding Window
#Queues
#Stream Processing
Software Engineer
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Coding
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medium
Implement a Connect 4 game. Provide a method to drop a token into a column and a method to check if a player has won.
#2D Arrays
#Matrix
#Game Logic
#Pair Programming
Software Engineer
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Coding
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medium
Write a thread-safe class to manage a user's cryptocurrency wallet balance, supporting concurrent deposits and withdrawals.
#Concurrency
#Mutex
#Locks
#Race Conditions
Software Engineer
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Coding
•
easy
Given an array of historical prices for a cryptocurrency, find the maximum profit you can achieve from a single buy and sell transaction.
#Arrays
#Dynamic Programming
#Two Pointers
Software Engineer
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Coding
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medium
Implement a pagination system for a REST API that returns a user's transaction history, supporting cursor-based pagination.
#API
#Data Manipulation
#Sorting
Software Engineer
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Coding
•
medium
Implement an LRU (Least Recently Used) Cache to store the most recently queried cryptocurrency prices.
#Linked Lists
#Hash Maps
#Caching
Software Engineer
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Coding
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easy
Write a function to validate if a given string is a valid Bitcoin or Ethereum address based on specific length and character set rules.
#Strings
#Regular Expressions
#Validation
Software Engineer
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Coding
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medium
Implement a text editor core engine that supports typing text, deleting text, and undo/redo functionality.
#Stacks
#Design Patterns
#Command Pattern
Software Engineer
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Coding
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hard
Design an alert system that triggers when a specific coin's price drops by more than X percent within a Y minute rolling window.
#Sliding Window
#Monotonic Queue
#Time Series
Software Engineer
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Coding
•
medium
Given a list of server downtime intervals (start_time, end_time), merge all overlapping intervals to find the total downtime.
#Sorting
#Intervals
#Arrays
Software Engineer
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Coding
•
medium
Implement a function to verify a transaction's inclusion in a Merkle Tree given the transaction hash, the Merkle Root, and the proof path.
#Trees
#Hashing
#Cryptography
Software Engineer
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Coding
•
hard
Implement an in-memory order book matching engine for a single trading pair (e.g., BTC-USD). It should support adding limit buy/sell orders and market orders, and execute trades when prices cross.
#Data Structures
#Priority Queues
#OOP
Software Engineer
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Coding
•
medium
Given a list of cryptocurrency exchange rates (e.g., BTC-USD = 60000, ETH-BTC = 0.05), write a function to find the best conversion rate between any two given currencies.
#Graphs
#BFS/DFS
#Shortest Path
Software Engineer
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Coding
•
hard
Implement an in-memory Key-Value store that supports nested transactions with BEGIN, COMMIT, and ROLLBACK operations.
#Data Structures
#State Management
#Stacks
Software Engineer
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Coding
•
medium
Design and implement a sliding window rate limiter for our public API to prevent abuse.
#Concurrency
#Queues
#System Design
Software Engineer
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Coding
•
easy
Given a user's current crypto portfolio balances and a target percentage allocation, write a function to calculate the minimum number of buy/sell trades required to rebalance the portfolio.
#Arrays
#Math
#Logic
Software Engineer
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Coding
•
medium
Write a function to merge K sorted streams of order book data into a single sorted stream.
#Heaps
#Pointers
#Sorting
Software Engineer
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Coding
•
medium
Write a program that connects to a mock WebSocket streaming JSON trade data, parses the messages, and maintains a rolling 1-minute average price for Ethereum.
#Streaming
#JSON Parsing
#Queues
Software Engineer
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Coding
•
medium
Implement an API wrapper that fetches a user's entire transaction history from a paginated endpoint, automatically handling rate limits and retries.
#API Integration
#Pagination
#Error Handling
Software Engineer
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Coding
•
medium
Design a simple blockchain data structure in code. Implement blocks, cryptographic hashing (SHA-256), and a function to validate the integrity of the chain.
#Cryptography
#Hashing
#Linked Lists
Software Engineer
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Coding
•
medium
Implement an LRU (Least Recently Used) Cache to store recent API responses for crypto price queries.
#Linked Lists
#Hash Maps
#Data Structures
Software Engineer
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Coding
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hard
Given an array of historical prices for a crypto asset, find the maximum profit you can achieve with at most two transactions (buy and sell).
#Dynamic Programming
#Arrays
Software Engineer
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Coding
•
medium
Write a parser for a simplified version of the FIX (Financial Information eXchange) protocol. Convert a raw FIX string into a structured dictionary/map.
#Strings
#Parsing
#Hash Maps
Software Engineer
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System Design
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hard
Design a cryptocurrency exchange matching engine capable of handling millions of orders per second.
#High Throughput
#Low Latency
#Event Sourcing
#Microservices
Software Engineer
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System Design
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medium
Design a real-time price ticker dashboard for millions of concurrent web and mobile clients.
#WebSockets
#Pub/Sub
#Redis
#Scalability
Software Engineer
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System Design
•
hard
Design the infrastructure for a secure cryptocurrency wallet system, including hot and cold storage management.
#Security
#Cryptography
#Key Management
#Distributed Systems
Software Engineer
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System Design
•
medium
Design a highly available API rate limiting service for Coinbase's public API.
#Redis
#Distributed Caching
#API Gateway
Software Engineer
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System Design
•
hard
Design a blockchain indexer that reads blocks from an Ethereum node and makes transaction histories searchable by user address.
#Data Pipelines
#ETL
#Databases
#Blockchain
Software Engineer
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System Design
•
medium
Design a notification system to send price alerts (Push, SMS, Email) to millions of users with low latency.
#Asynchronous Processing
#Message Queues
#Microservices
Software Engineer
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System Design
•
hard
Design a system to handle a massive airdrop of a new token to 10 million eligible users at a specific time.
#Batch Processing
#Scalability
#Database Locking
Software Engineer
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System Design
•
hard
Design a fiat-to-crypto payment gateway that integrates with traditional banks and blockchain networks.
#Payment Systems
#State Machines
#Third-party Integration
Software Engineer
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System Design
•
hard
Design a scalable ledger database system to track user fiat and crypto balances securely.
#Databases
#ACID
#Immutability
#Double Entry Accounting
Software Engineer
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System Design
•
medium
Design a real-time fraud detection system to flag suspicious cryptocurrency withdrawals.
#Stream Processing
#Machine Learning
#Rules Engine
Software Engineer
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System Design
•
hard
Design the backend architecture for a cryptocurrency exchange. Focus on the order matching engine and how it interacts with user balances.
#Microservices
#Concurrency
#Matching Engine
#ACID
Software Engineer
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System Design
•
medium
Design a real-time price ticker dashboard for Coinbase's homepage that serves millions of concurrent users.
#WebSockets
#Pub/Sub
#Caching
#Scalability
Software Engineer
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System Design
•
hard
Design a reliable fiat-to-crypto payment gateway that integrates with third-party banks and handles deposits and withdrawals.
#Idempotency
#Payment Gateways
#Distributed Systems
Software Engineer
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System Design
•
hard
Design Coinbase's wallet infrastructure, specifically focusing on how to securely manage hot and cold wallets.
#Security
#Cryptography
#Key Management
#Air-gapping
Software Engineer
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System Design
•
medium
Design a system to execute a token airdrop to 10 million eligible users within a 24-hour window.
#Batch Processing
#Scalability
#Message Queues
Software Engineer
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System Design
•
hard
Design a distributed double-entry accounting ledger for internal user balances.
#Databases
#ACID
#Distributed Systems
#Event Sourcing
Software Engineer
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System Design
•
medium
Design a global rate-limiting service for Coinbase's public API that can handle millions of requests per second.
#Redis
#Distributed Systems
#API Gateway
Software Engineer
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System Design
•
medium
Design a notification system that allows users to set custom price alerts (e.g., 'Email me when BTC drops below $60k').
#Stream Processing
#Notifications
#Databases
Software Engineer
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System Design
•
hard
Design a system to monitor multiple blockchains and alert internal systems of chain reorganizations (reorgs) or orphaned blocks.
#Blockchain
#Event Sourcing
#Monitoring
Software Engineer
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System Design
•
hard
Design a real-time fraud detection system for users purchasing crypto with credit cards.
#Machine Learning Infrastructure
#Real-time Processing
#Data Pipelines
Software Engineer
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Technical
•
medium
In a backend system, how do you handle arithmetic operations for cryptocurrency balances to avoid floating-point precision loss?
#Data Types
#Precision
#Backend Engineering
Software Engineer
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Technical
•
medium
Given a 'trades' table with columns (trade_id, user_id, amount, price, created_at), write a SQL query to find the top 5 users by total trading volume in USD over the last 7 days.
#SQL
#Aggregations
#Data Analysis
Software Engineer
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Technical
•
hard
Explain how you would design a database schema and transaction flow to prevent double-spending when a user initiates two simultaneous withdrawal requests.
#Databases
#Concurrency
#Transactions
#Locking
Software Engineer
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Technical
•
hard
Explain how you would ensure idempotency in a distributed microservices architecture handling financial transactions.
#Distributed Systems
#Idempotency
#Microservices
Software Engineer
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Technical
•
medium
How do you handle database schema migrations with zero downtime in a high-traffic, 24/7 environment like Coinbase?
#Databases
#DevOps
#Deployment
Software Engineer
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Technical
•
medium
Explain the fundamental differences between Proof of Work (PoW) and Proof of Stake (PoS), and discuss the engineering trade-offs when building services that interact with them.
#Blockchain
#Consensus Mechanisms
#Crypto
Software Engineer
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Technical
•
hard
How would you secure a microservice architecture that processes and stores highly sensitive financial and PII data?
#Microservices
#Encryption
#Authentication
Software Engineer
•
Technical
•
medium
Discuss the trade-offs between using a Relational Database (like PostgreSQL) versus a NoSQL Database (like DynamoDB) for storing a user's cryptocurrency transaction history.
#Databases
#Trade-offs
#Data Modeling
Difficulty Radar
Based on recent AI-sourced data.
Meet Your Interviewers
The "Standard" Interviewer
Senior EngineerFocuses on core competencies, system constraints, and clear communication.
SimulateUnwritten Rules
Think Out Loud
Always explain your thought process before writing code or drawing architecture.