TypeScript
606TypeScript adds a structural type system on top of JavaScript. Most of the difficulty sits in what the compiler infers, not in what you wrote.
125 easy · 219 medium · 262 hard
Browse 9,481 coding interview questions
Seventeen languages, each with its own topic list and a code snippet on every question. Pick a language to read through it, a difficulty to run a mixed set, or a curated test for a timed paper.
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This is the practice bank. The questions we send to candidates in a recruiter test come from a separate sealed set that is never published here, and each candidate gets a different draw.
By language
MongoDB
589MongoDB is a document database. Its interviews are about data modelling and index design far more than about query syntax.
99 easy · 246 medium · 244 hard
SQL
587SQL is the query language every relational database speaks. Interviews test whether you can reason about set semantics, not just write SELECTs.
105 easy · 236 medium · 246 hard
JavaScript
580JavaScript runs in every browser and, through Node, on most back ends too. It is the language with the widest reach and the most edge cases.
110 easy · 221 medium · 249 hard
C#
580C# is the .NET language for services, desktop apps and games. Its interviews go deep on value versus reference semantics.
76 easy · 258 medium · 246 hard
Go
576Go is built for concurrent network services. The runtime is small enough that interviews expect you to know how it behaves.
89 easy · 244 medium · 243 hard
HTML
574HTML is the document layer of the web. Getting it right is most of accessibility and a surprising amount of SEO.
124 easy · 225 medium · 225 hard
Python
570Python is the default language for scripting, data work, and back-end services that value readability over raw speed.
115 easy · 211 medium · 244 hard
Rust
566Rust enforces memory safety at compile time. Interviews mostly test whether the borrow checker's model is in your head.
75 easy · 241 medium · 250 hard
Ruby
557Ruby is a dynamic, deeply reflective language best known through Rails. Its metaprogramming is both the draw and the trap.
50 easy · 247 medium · 260 hard
Swift
549Swift is Apple's language for iOS and macOS. Reference-counting behaviour and value semantics drive most of its gotchas.
60 easy · 245 medium · 244 hard
Java
541Java runs a very large share of enterprise back ends. Its interviews reward knowing the memory model as well as the syntax.
112 easy · 211 medium · 218 hard
React
536React is the dominant way to build user interfaces on the web. The hard parts are re-render timing, identity, and effect cleanup.
120 easy · 218 medium · 198 hard
CSS
527CSS decides layout and paint. Most bugs come from the cascade, stacking contexts, and containing blocks rather than from the properties themselves.
128 easy · 198 medium · 201 hard
C++
523C++ gives direct control over memory and object lifetime. Almost every interview question is really a lifetime question.
82 easy · 235 medium · 206 hard
NodeJS
519Node puts JavaScript on the server with a single-threaded event loop and a large streaming and process API surface.
103 easy · 216 medium · 200 hard
Kotlin
505Kotlin is the default language for Android and a common Java replacement on the JVM. Coroutines are its defining feature.
63 easy · 218 medium · 224 hard
By difficulty
Curated timed tests
11 fixed papers with a deliberate difficulty mix, from 10 to 20 minutes each.