Senior Frontend Practice Platform
Deep practice for Senior, Lead & Staff engineers.
Coding problems, architecture drills, and internals-heavy quizzes — calibrated for real interviews.
// Hard · ~60 min · Meta, Vercel
type VNode = {
tag: string;
props: Record<string, unknown>;
children: VNode[];
}
export function diff(
oldTree: VNode,
newTree: VNode
): Patch[] {
// your implementation
}
5+
Coding Problems
2
Quiz Packs
3
Deep Guides
2
System Design
Practice modes
Four surfaces. One mission: advancing careers through deliberate depth.
Coding Problems
Implementation and debugging rounds with visible I/O examples and hidden edge-case test suites. Pass all to move on.
5+ problems · Easy / Medium / Hard
Internals Quizzes
MCQ and spot-the-bug questions that test event loop ordering, reconciler phases, and scheduler priority — with deep explanations.
2 quizzes · MCQ / Spot-the-bug
Deep-Dive Guides
Long-form architecture and performance reference on React Fiber, TypeScript type system internals, and the browser rendering pipeline.
3 guides · Long-form
System Design
Architecture drills: design a component library, spec a real-time collaboration editor, plan a design system API from scratch.
2 scenarios · Frontend Architecture
Built for the 5+ year engineer
Every design decision optimised for depth, not completion rate.
Three difficulty levels
From fundamentals to advanced — Easy, Medium, and Hard problems calibrated for real interview rounds.
Hidden test cases
Visible tests show I/O examples. Hidden tests validate edge cases — just like real technical interviews.
React internals coverage
Fiber, lanes, reconciler phases, Suspense boundaries — with test cases that prove deep understanding.
Performance debugging
Layout, reflow, and compositor drills that mirror real production performance incidents.
Spot-the-bug problems
Identify subtle bugs in production-realistic code snippets, then explain why and how to fix correctly.
In-browser test runner
Your code runs against real test suites with instant pass/fail feedback per case — no waiting.