Actually understand it.
Three structured tracks: master JavaScript exceptions with the WHY, learn DSA patterns with in-browser coding, and design systems with diagrams and real challenges.
Caching stores frequently accessed data in fast storage so future requests skip the slow source โ cutting latency and reducing DB load at scale.
Most engineers need all three. TechCookies covers them together so you don't have to juggle five different resources.
Learn JavaScript the right way โ not just syntax, but the engine mechanics behind type coercion, closures, async, and 316 documented exceptions, each with the WHY.
Master algorithmic patterns (two-pointer, sliding window, BFS, dynamic programmingโฆ) with guided concept sections, then practice in-browser with real test cases โ no setup needed.
Learn caching, databases, load balancers, queues, and more through structured concept pages with inline architecture diagrams. Then apply everything in real end-to-end system design challenges.
Not just content. A structured path from understanding a concept to using it โ whether that's predicting JS output, solving a coding problem, or designing a real system.
Two free concepts to start. Upgrade to unlock the full curriculum.
6 free patterns to start, covering the foundational techniques every interview tests.
13 free concepts to start. Every concept explains not just what JavaScript does, but why the engine behaves that way.
No credit card required. All three tracks included on every plan.
Yes. Caching and load balancing are among the most commonly tested system design concepts. You also get the URL shortener SD challenge, practice tests, and full notes/flashcard functionality.
36 JS concepts ยท 316 exceptions ยท 17 DSA patterns ยท 39 problems ยท 94 SD concepts. Free to start.