Work in three phases over 6–8 weeks. First, learn the building blocks — load balancing, caching, SQL vs NoSQL databases, sharding, replication, message queues and CAP trade-offs. Next, study classic designs such as a URL shortener, chat app, news feed, rate limiter and payment system, always attempting the design yourself before reading a reference solution. Finally, do timed mock sessions where you talk through the design out loud, since interviewers score your clarifying questions and trade-off reasoning as much as the final architecture.

Use a repeatable framework instead of jumping to a solution: clarify functional and non-functional requirements, estimate the scale (users, requests per second, storage), sketch a high-level design, deep-dive into two or three components the interviewer cares about, and close with bottlenecks, failure handling and trade-offs. Keep narrating your thinking throughout — staying silent while drawing is the most common reason otherwise strong candidates fail design rounds.

The most common system design interview questions repeat across almost every company: design a URL shortener, a WhatsApp-style chat system, an Instagram-style feed, a rate limiter, a notification service, a distributed key-value store, a parking lot system and a payment or wallet system. Don't memorise individual answers — learn one framework and practice remapping it to each scenario, because interviewers routinely tweak the problem to test whether you genuinely understand the trade-offs.

The System Design Interview book by Alex Xu (Volume 1 and Volume 2) is one of the best starting resources — it explains the standard building blocks and walks through the most frequently asked designs in simple language. On its own, though, it is not enough for mid-level or top-company loops. Combine it with hands-on practice, real-world engineering blogs and a few live mock discussions, because these interviews test how you reason under pressure rather than what you have memorised.

Grokking the System Design Interview is a widely used online course that teaches design through a step-by-step framework with worked examples such as TinyURL, Dropbox and a Twitter timeline. It is genuinely helpful if you are starting from zero and don't know how to structure an answer. Use it to internalise the method, then move on to tougher, less familiar problems and live practice, since relying only on its standard examples can make your answers feel rehearsed to experienced interviewers.

A LeetCode interview is a coding round built around data structures and algorithms problems of the type you practice on LeetCode — arrays, strings, hashmaps, trees, graphs and dynamic programming — usually solved in 30–45 minutes while explaining your approach out loud. Most product companies in India use this format for at least one or two rounds, typically on a shared code editor, so practicing timed, talked-out problem solving matters more than just knowing the solutions.

Yes — LeetCode is still the most effective tool for building pattern recognition for DSA rounds, and most questions asked at product companies map to a limited set of patterns. The key is quality over quantity: roughly 150–200 problems solved with full understanding, organised by topic and pattern, beats grinding 800 random problems. Just remember LeetCode alone won't cover system design, projects or behavioral rounds, so treat it as one pillar of your preparation, not the whole plan.

Company-wise LeetCode interview questions are best sourced from LeetCode's company-tagged problem lists and its Discuss section, where candidates post the exact questions they were asked, sorted by recency. Crowd-sourced sheets for specific companies — Meta/Facebook, Uber, Amazon, Google, Flipkart and others — also circulate widely and are often more current than anything else. Focus on the last 3–6 months of reported questions, since companies rotate their question banks frequently.

Treat it as three parallel tracks: DSA (patterns over raw volume, with consistent daily practice), system design (a clear framework plus the classic problems, once you're past entry level), and your own projects plus behavioral stories in STAR format. Before each company's loop, research its interview style and recent questions, and do at least three to five mock interviews with a friend or mentor — articulating your thought process out loud is often the difference between a strong candidate and a rejection, even with identical coding skills.

Software engineer interview questions for freshers typically fall into four buckets: DSA basics (arrays, strings, linked lists, recursion and simple dynamic programming), core CS subjects like OOP, DBMS, operating systems and networks, deep questions on the projects listed on your résumé, and sometimes aptitude or pseudocode rounds, especially at services companies. Build one or two projects you can defend in depth and practice explaining your decisions clearly — for freshers, interviewers test fundamentals and clarity of thought far more than scale experience.

Google's process usually starts with one or two coding screens followed by a loop covering coding, system design (for L4 and above) and Googleyness/behavioral rounds. The bar sits on problem-solving depth: clarifying questions before coding, clean and correct code, complexity analysis and edge cases all matter, along with clear communication throughout. Plan three to four months of preparation, practice medium-to-hard problems under timed conditions, revise core design fundamentals, and rehearse thinking aloud, because Google explicitly scores how you collaborate with the interviewer.