Review: File Download Route Written by an AI Assistant
Your team asked an AI coding assistant to let users download the files they have uploaded to a document-sharing app. It opened this pull r...
Interview practice for the AI era
Practise the interview that exists now.
Interviews now test how you work alongside AI: reviewing code an assistant wrote, fixing what it broke and designing the systems around it. Practise every round in your browser, scored exactly, with AI feedback that stays on your device.
Also: SQL · Specialist tracks · Study plan
- 6Interview rounds, including AI code review
- 169Coding and DSA problems
- 140SQL and system design problems
- FreeNo account, nothing to install
Interview rounds
Every round you will face, in one workspace
Classic rounds are still asked. The new ones test the work you actually do with AI tools.
New
Review AI code
An assistant opened a pull request. Flag the bugs, security holes and race conditions before it merges. Scored line by line against an answer key.
In development
Fix and extend AI code
Working code with failing tests. Find what the assistant got wrong, fix it, then add a feature without breaking anything.
Coding and DSA
Problems grouped into 17 patterns, from arrays to dynamic programming. Python, JavaScript and TypeScript are judged automatically.
System design
From a URL shortener to payments, including AI systems such as RAG, inference serving and agents, with a whiteboard and estimator.
SQL
Queries run on a real database in your browser: joins, window functions, funnels and retention, checked on hidden data.
Low-level design
Object-oriented design with class diagrams and runnable code: parking lot, elevator, expense sharing, chess and more.
How you are judged
Exact scores first. AI feedback on top.
A score you can trust comes from checks, not opinions. AI then explains what a strong candidate would have said.
Exact checks, every time
Hidden tests for code, hidden datasets for SQL, and a line-by-line answer key for reviews. Missing a critical bug fails the round, as it would in a real loop.
AI feedback on your device
In Chrome, a built-in model reads your review and coaches you on clarity and seniority. Nothing leaves your device and it costs nothing.
No keys, no accounts
Nothing to sign up for and no API keys. Scoring and feedback run in your browser, and your answers never leave your device.
Interview conditions
Mock timers lock hints and answers, and progress, streaks and spaced reviews stay in your browser with nothing to sign up for.
Specialist tracks
For the roles generic prep ignores
Each track has a full roadmap and interview guide, and a question bank with model answers, coding exercises with tested solutions, design and debugging scenarios and a mock interview plan.
Algo trading
Alpha research, backtesting without bias, market microstructure, execution and low-latency C++, plus the probability puzzles quant firms ask.
Device driver developer
Linux kernel drivers: probe and remove, interrupts, locking, DMA, PCIe, USB, device tree and kernel debugging.
Firmware developer
Bare-metal microcontrollers: startup code, linker scripts, bootloaders, OTA updates, RTOS, low power and fault analysis.
Embedded programmer
C for embedded, volatile and bit manipulation, interrupts, RTOS, buses, embedded Linux and device design.
Robotics engineer
ROS 2, transforms, kinematics, control, Kalman filters, SLAM, motion planning and perception.
Coming next: FPGA engineer and framework developer tracks.
Roadmaps
A roadmap for every role
The full path for each job, from first topic to interview loop, with linked skill roadmaps.
Software
- Software EngineerDSA, system design, LLD
- Front End EngineerJavaScript, UI, web performance
- Back End EngineerAPIs, databases, scaling
- Full Stack DeveloperEnd-to-end product rounds
- Mobile DeveloperCross-platform apps
- Android DeveloperKotlin, Jetpack Compose
- iOS DeveloperSwift, SwiftUI, UIKit
- Software ArchitectArchitecture and trade-offs
- QA and SDET EngineerTest design, automation
- Blockchain DeveloperSmart contracts, security
Data and AI
- Data AnalystSQL, metrics, product sense
- BI AnalystSQL, modelling, dashboards
- Data ScientistSQL, statistics, ML
- Data EngineerSQL, pipelines, warehouses
- Machine Learning EngineerML coding, ML system design
- MLOps EngineerTraining, serving, monitoring
- AI EngineerLLMs, RAG, agents, evaluation
- Forward Deployed EngineerAI deployments with customers
- Inference EngineerServing models fast and cheaply
- AI Product BuilderShipping AI features end to end
Infrastructure and systems
- DevOps and SRE EngineerLinux, cloud, reliability
- DevSecOps EngineerSecurity in the delivery pipeline
- Cloud EngineerArchitecture, networking, cost
- Security EngineerAppSec, threat modelling
- Network EngineerRouting, switching, automation
- Database AdministratorPostgreSQL, backups, tuning
- Embedded Systems EngineerC, RTOS, drivers, memory
- Robotics Software EngineerC++, ROS, control, perception
- Game DeveloperC++, engines, maths
- Server Side Game DeveloperMultiplayer backends
Study plan
A plan that works for any role
Five steps, in order. Most people need four to eight weeks.
- Pick one languageGet fluent with its collections, strings and recursion.
- Learn the patternsWork through the Pattern Path one topic at a time, easy to hard.
- Add SQL and designMost interview loops include a data or design round.
- Run mock interviewsUse the timer with hints locked, and explain your thinking out loud.
- Review on scheduleRe-solve problems from memory when the review queue asks.
Articles
Latest interview guides
FAQ
Frequently asked questions
How the site works, and how to use it to prepare.
Is CodingInterview.net really free?
Yes. Every problem, hint, solution, the code editor, the SQL database, the system design whiteboard and the progress tracker are free, with no account and no paywall.
Which interview rounds can I practise here?
Coding and data structures & algorithms, SQL, high-level system design (including AI and LLM systems such as RAG, inference serving and AI agents) and low-level object-oriented design. Role guides cover what each role is asked, from software and data to embedded, robotics, DevOps and mobile.
Which programming languages are supported?
Python, JavaScript and TypeScript are judged automatically in your browser. Java, C++, C, C#, Go, Kotlin, Rust, Swift, Ruby, PHP and Scala run in the built-in online compiler.
Do I need to sign up or install anything?
No. Everything runs in your browser. Your progress, code and notes are saved privately on your device, and you can export a backup from the progress page.
How should I prepare for a coding interview in 4 to 8 weeks?
Pick one language, then work through the Pattern Path one technique at a time, two to four problems a day. Add a SQL or system design session twice a week, do a timed mock interview every weekend, and clear your review queue daily.
Is this useful for interviews at any company, in any country?
Yes. The questions cover the patterns and design topics that technical interviews use worldwide, from large tech companies to startups, and everything is written in clear international English.
Start with one problem today.
Pick a round, solve one problem, and let the review queue bring it back when it is due.