Skills
507 skills, each with practice questions and problems. Pick one to see its questions, the roles that need it and related skills.
Data Structures & Algorithms
Statistics 45Arrays 33Strings 29Hash Map 29Math 23Sorting 20Simulation 16Dynamic Programming 16Greedy 15Two Pointers 13Sliding Window 13Matrix 13Graph 13Heap 12Binary Search 11Parsing 11System Design 10Bit Manipulation 10DevOps 10Tree 10Stack 9Linked List 9Bfs 9Fintech 8Frontend 8Dfs 7Prefix Sum 6Counting 6Machine Learning 6Data Processing 6Recursion 6Backtracking 6Dates 5Intervals 5Queue 5Union Find 4Divide And Conquer 4Topological Sort 4
Software Engineering
Performance 82Security 45Reliability 38JavaScript 31Debugging 31Smart Contract Security 29Networking 28Unity 28HTTP 27Web Security 25Solidity 25Cryptography 23Embedded C 23API Design 22Concurrency 21Deployment 21Authentication 19Rendering 18EVM Fundamentals 17Node.js 16Distributed Systems 16Caching 15Android 14Interrupts 14Next.js 13Databases 13CSS 12Web Performance 12Memory 12React 11Multiplayer 11Physics 10Architecture 9Token Standards 9RTOS 9React Hooks 8Testing 8Redis 8Mobile Security 8Jetpack Compose 8Memory Management 8Communication Protocols 8TypeScript 7Message Queues 7Swift 7Flutter 7React Native 7Game Loop 7Vector Math 7DEFI 7Event Loop 6Responsive Design 6Async Javascript 6Error Handling 6Kotlin Coroutines 6Game Math 6Unreal 6Upgradeability 6Blockchain Fundamentals 6Layer 2 6Openzeppelin 6Gpio 6FreeRTOS 6State 5HTTP Caching 5Authorization 5JWT 5Async Programming 5Data Structures 5API Security 5Feature Flags 5iOS 5Swift Concurrency 5Background Work 5Animation 5Gas 5Dapp Frontend 5Testing And Fuzzing 5Foundry 5Bitwise Operations 5Memory Layout 5Hardware Debugging 5Semantic HTML 4HTML 4React State 4React Server Components 4State Management 4REST API Design 4Rate Limiting 4Database Performance 4Async Await 4Swiftui 4Push Notifications 4Kotlin Flow 43d Transforms 4Game AI 4Gas Optimisation 4Timers 4Integer Types 4I2C 4Mcu Architecture 4Low Power Design 4
Data, AI & Machine Learning
SQL 115A/B Testing 36Monitoring 31Evaluation 31RAG 29Metrics 28Joins 17Classification Metrics 17Data Quality 17Window Functions 15Data Modeling 15Python 14LLM Serving 14Aggregation 13Embeddings 13Pandas 13Agents 13Structured Output 12Tool Calling 12Null Handling 12Kafka 11Model Serving 11Drift 11Data Leakage 10Descriptive Statistics 10Excel 10Spark 10Idempotency 9Model Evaluation 9Feature Engineering 9LLM Safety 9Probability 9Distributed Training 9Fine Tuning 9Sampling 9Causal Inference 9Orchestration 9Transformers 8Vector Search 8LLM As Judge 8Linear Algebra 7PyTorch 7Time Series 7LLM Basics 7Streaming 7Guardrails 7Prompt Injection 7Data Visualisation 7Airflow 7Instruction Design 7Data Visualization 7Training 6Deep Learning 6Feature Store 6Product Analytics 6Reproducibility 6Few Shot Prompting 6LLM Fundamentals 6Dbt 6Tokens 5Calibration 5Attention 5GPU Memory 5Bias 5Prompt Design 5Hypothesis Testing 5Missing Data 5Linear Regression 5Cost Management 5Prompt Debugging 5Business Math 5Incremental Loads 5Feature Scaling 4Clustering 4Tokenization 4Data Cleaning 4Lora 4Class Imbalance 4ML Basics 4Retrieval Metrics 4Context Window 4Causal Thinking 4Multiple Testing 4Model Monitoring 4Inference Optimisation 4GPU 4Chain Of Thought 4Cohort Analysis 4Power BI 4Scd 4Lakehouse 4
Cloud, DevOps & Security
Kubernetes 59PostgreSQL 57Incident Response 27Terraform 25Observability 24Indexing 24Infrastructure As Code 24Cost Optimization 23Troubleshooting 22Docker 20Prometheus 20Data Modelling 18Transactions 17Cloud Security 17High Availability 16Latency 15IAM 14VPC Networking 14Secrets Management 12Deployment Strategies 12Replication 12Alert Triage 12Linux 11Cloud Storage 11Query Tuning 11Alerting 9Backup Recovery 9MySQL 9Network Security 9Detection Engineering 9Git 8Scalability 8GitHub Actions 8Devsecops 8Slos 8Database Security 8DNS 7Resource Management 7Phishing Analysis 7Windows Event Logs 7Mitre Attack 7EDR 7Serverless 6Autoscaling 6On Call 6Opentelemetry 6Cloud Databases 6K6 6Capacity Planning 6Partitioning 6Log Analysis 6Identity Security 6Threat Intelligence 6Vulnerability Management 6Threat Hunting 6Logging 5Tracing 5Resilience 5AWS 5Container Security 5Supply Chain Security 5Automation 5Linux Performance 5Mvcc 5Security Fundamentals 5Cloud Identity 5Gitops 4Cloud Fundamentals 4Compute 4Encryption 4Disaster Recovery 4Messaging 4Network Design 4Error Budgets 4Slis 4Promql 4Locking 4Malware Triage 4Email Security 4Windows Logs 4Network Fundamentals 4Active Directory Security 4
Quality & Testing
CI/CD 37API Testing 24Test Design 23Playwright 17Test Strategy 14Flaky Tests 13Performance Testing 10Security Testing 9Selenium 7Framework Design 7Locators 6Mobile Testing 6Reporting 6Test Types 5Accessibility Testing 5Test Automation 5Contract Testing 5Waits 5Readability 5Test Data 5Mocking 4Bug Reporting 4Testing Fundamentals 4Boundary Value Analysis 4Test Scenarios 4UI Automation 4Parallel Testing 4Test Isolation 4
Design
Accessibility 42Print Production 25Typography 17File Formats 12Layout 9Interaction Design 9Branding 9Colour Management 9User Research 8Client Communication 8WCAG 7Usability Testing 7Colour Theory 7Logo Design 7Research Methods 6Forms 5Design Systems 5UX Metrics 5Collaboration 4Visual Hierarchy 4Information Architecture 4Heuristics 4Research Bias 4Image Quality 4Design Principles 4Adobe Photoshop 4Digital Design 4Adobe Indesign 4
Product & Project
Stakeholder Management 53Prioritisation 24Experimentation 20Discovery 20Product Metrics 18Risk Management 15Scheduling 14Governance 12Business Case 12Strategy 11Scrum 11Earned Value 11Elicitation 11BPMN 10Agile 9User Stories 9Data Analysis 9Critical Path 8Financial Analysis 7Scope Management 6Acceptance Criteria 6Procurement 6Retention 5Backlog Management 5Launch 5Business Metrics 5Agile Metrics 5Cost Forecasting 5Requirements Quality 5Process Modelling 5Estimation 4Growth 4Quality Management 4Status Reporting 4Change Control 4Team Leadership 4UML 4
Marketing, Sales & People
Ethics 35Compliance 31Negotiation 27Unit Economics 22Pipeline Management 21Prospecting 19Analytics 18Contracts 17Recruiting Metrics 17Forecasting 16Technical SEO 16Core Web Vitals 15Pricing 15Grammar 15Fair Hiring 13Communication 12Editing 12Qualification 12Partnerships 12Objection Handling 12Interviewing 11CRM 11Renewals 11Onboarding 10Content Analytics 10Sourcing 10Offers 10Marketing Metrics 9Google Ads 9Copywriting 9Sales Analytics 9Closing 9Candidate Experience 9Churn Prevention 9Retention Metrics 9Measurement 8Privacy 8Customer Feedback 8Spam Policies 8SEO Writing 8Value Selling 8Email Marketing 7GA4 7Internal Linking 7Content Strategy 7Punctuation 7Funnel Metrics 7Deal Strategy 7Data Privacy 7Segmentation 6Attribution 6On Page SEO 6Redirects 6Clear Writing 6SEO Basics 6Research 6Fact Checking 6Sales Metrics 6Job Descriptions 6Escalation Management 6UX Writing 5Copyright 5Structured Data 5Data Literacy 5Channel Sales 5Enterprise Sales 5Deal Structuring 5Account Management 5Boolean Search 5Compensation 5Health Scores 5SAAS Metrics 5Customer Communication 5Cs Operations 5Freelancing 4Conversion Tracking 4Cro 4Meta Ads 4ROAS 4Smart Bidding 4Email Deliverability 4Incrementality 4Search Intent 4Robots Txt 4Status Codes 4Content Structure 4Link Building 4E-E-A-T 4Content Quality 4International SEO 4Javascript SEO 4AI Overviews 4Style Guides 4Sales Tools 4Proposals 4Handoff 4Sales Compensation 4Structured Interviews 4Product Adoption 4Digital Cs 4Churn Analysis 4