Find out what you'd fail on before the interviewer does.
Practice the questions you'll actually be asked, get graded on what you actually wrote, and see exactly which subtopics would sink you.
Free plan, no card. Ten real questions and a real score.
Try it now — no account
What do generic constraints do? Walk me through where T : class,
where T : struct, where T : new() and
where T : IComparable<T>, and say what you can do inside the method
once each is applied.
- reviewed questions
- 1,160
- tracks, 5 fully live
- 12
- subtopics scored separately
- 490
- tests vs code review
- 70/30
reviewed questions
tracks, 5 fully live
subtopics scored separately
tests vs code review
Learn the basics first, with a real compiler
Six reference courses on the languages people actually get hired in, each lesson with an example you run for real and a task you have to solve — graded by the same sandbox that grades an interview answer, with your own mistakes underlined on the line they happened.
Browse the coursesclass Point {
final int x, y;
Point(int x, int y) { this.x = x this.y = y; }
}';' expected — line 3
Why not just ask a chatbot?
Four things a chat window cannot do, and a question bank alone will not give you.
Graded on what you actually wrote
Every theory answer is scored against a fixed rubric. Each bullet shows whether you covered it, and quotes the phrase from your own answer that earned the mark. The percentage is arithmetic on that list, never a model's guess at a number.
IQueryable builds an expression tree the provider translates to SQL
From your answer:
IQueryable keeps an expression tree that EF turns into SQL
Covered30Filtering an IQueryable happens in the database
From your answer:
the where goes to the database I think
Partial25Both are deferred until enumeration
Not mentioned
Missing10
Your code actually runs
Tests decide whether it works, in a throwaway sandbox. Seventy per cent of a coding score is tests passing; the review only judges quality.
- counts_multiple_ordersPassed
- ignores_cancelledFailed
input: 3 orders, 1 cancelled actual: 3
- hidden_1 Hidden testPassed
It remembers what you got wrong
Weak subtopics come back on a schedule until they stop being weak. Strong ones retire. No grinding the same question you already know.
- 85–100+21d, then +45d, then retired
- 70–84+14d
- 50–69+5d
- 0–49+2d
A score that means something to a hiring manager
Every score is labelled with the level it was measured against, because “68” on its own is meaningless. Questions are hand-written and reviewed, so a wrong premise never wastes your time.
68 / 100 — Needs work for Junior
Know exactly where you would fail
Every answer rolls into a subtopic heatmap. Teal is fine, amber is shaky, coral is the question that ends the interview.
Indexes & execution plans — 31%. You wrote working queries but could not explain why a leading wildcard prevents an index seek. Expect a follow-up on this in any SQL round.
C#
- Value vs reference types82%
- Collections & LINQ74%
- async/await & Task61%
- Generics70%
- Exceptions45%
- Delegates & events38%
SQL Server
- Joins74%
- Window functions52%
- Indexes & seeks vs scans31%
- Execution plans28%
- Transactions & isolation44%
- Deadlocks—
- 0–39
- 40–69
- 70–100
- Not yet assessed
Questions
- Is this just another question list?
- No. You answer, and every answer is graded: theory against a fixed rubric that quotes your own words back to you, code by actually running it against hidden tests.
- Which stacks are covered?
- Languages, frameworks, databases and cross-cutting skills. One plan covers every live and beta track, because full-stack developers should not pay four times.
- How long does a session take?
- Ten questions is about 25 minutes. Twenty is the usual choice the week before an interview. Thirty is a full loop simulation.
- What if the grade is wrong?
- Every attempt has a dispute button. A person reads it, and your score is corrected when the grader got it wrong.
Your next interview is a week away.
Ten questions, a real score, and a list of what to fix. Free, no card.