Build the fundamentals first — scalability, load balancing, caching, SQL vs NoSQL, sharding, replication, message queues, and consistency. Study 8–10 standard designs like a URL shortener, chat app, and news feed instead of memorising dozens, and lock a consistent answering framework: requirements, estimations, high-level design, deep dive, trade-offs. The best way to practice for a system design interview is doing timed mock designs — pick a prompt, design out loud for 40 minutes, and get feedback from an experienced mentor or peer.

Follow a clear structure: clarify functional and non-functional requirements, do quick back-of-the-envelope estimates, define the API, sketch the high-level architecture, then deep-dive into one or two components such as database schema, caching, or partitioning. Close by discussing bottlenecks and trade-offs. Interviewers evaluate how you think and justify decisions, so keep talking through your reasoning instead of jumping straight to a diagram.

The classics include designing a URL shortener, a WhatsApp-style chat app, an Instagram or Twitter feed, a video platform like YouTube, a ride-sharing app like Uber, a payment wallet, cloud storage like Google Drive, a rate limiter, and a notification system. Most of these test the same underlying concepts, so mastering 8–10 designs thoroughly covers the majority of what actually shows up in real rounds.

The System Design Interview book is one of the best starting points — Volume 1 and Volume 2 explain core concepts like consistency, caching, and sharding through well-known problems with clear diagrams. But reading alone rarely gets you through, because these rounds test live articulation under time pressure. Use the book for concepts, then supplement with hands-on problem practice and timed mock design rounds with feedback.

Grokking the System Design Interview is a widely used interactive online course that teaches system design through frequently asked problems, such as designing a URL shortener or a chat system, in a repeatable case-study format. It is helpful for beginners who need a structured starting framework, but like any single resource, it should be combined with self-driven practice and mock design interviews rather than treated as a complete solution.

Prepare topic by topic — arrays, strings, hashing, two pointers, sliding window, stacks, linked lists, binary search, trees, heaps, graphs, recursion, and dynamic programming. Solve a focused set of quality problems in each pattern instead of randomly attempting hundreds, maintain revision notes, and analyse time and space complexity for every solution. In the final weeks, shift to timed problem-solving and mock interviews to simulate real interview pressure.

Start by restating the problem and clarifying constraints, then state the brute-force approach with its complexity before optimising step by step. Think out loud throughout — interviewers assess your reasoning and communication as much as your final code. Write clean code with meaningful variable names, dry-run it against edge cases, and finish by clearly stating the overall time and space complexity.

There is a reason portals maintain separate DSA interview questions and answers for experienced candidates and freshers. Fresher rounds focus on fundamentals — arrays, strings, linked lists, basic recursion, and easy-to-medium problems with more hints allowed. For experienced candidates, expectations jump sharply: medium-to-hard DP and graph problems, optimal solutions expected quickly, follow-ups on scaling your approach, and additional LLD or system design rounds in the same interview.

Along with standard problems on arrays, strings, and trees, Java-focused rounds often probe HashMap and HashSet internals, ArrayList vs LinkedList, String immutability, and equals/hashCode. Classic implementation questions include LRU cache, merge intervals, and trie-based problems. Since Java dominates most Indian service-based companies and is common in product companies too, pick one language, master its collections, and solve every practice problem in it consistently.

GeeksforGeeks is a strong free resource, especially for company-wise question archives and placement-focused theory. But reading solutions is not the same as solving under pressure. Use it to shortlist frequently asked questions for your target companies, then actually solve them on a practice platform, add LeetCode for depth, and finish with timed mock interviews and feedback. The combination, not any single site, gets results.

Keep it to one page early in your career, with clear sections: contact details with GitHub and LinkedIn links, technical skills, experience or projects, and education. Write every bullet as action + technology + measurable outcome — "reduced API latency by 40%" beats "worked on backend". Mirror keywords from the job description so it clears ATS filters, and cut generic objective statements and long skill dumps.

Use a clean, single-column, ATS-friendly layout in reverse-chronological order, a readable 10–12 pt font, consistent spacing, and clear section headings. Replace paragraphs with short bullet points, keep margins around 0.5–1 inch, and save the file as a PDF named like FirstName_LastName_Resume.pdf. Recruiters spend only a few seconds on the first scan, so your strongest points should sit in the top third.

A software engineer resume PDF is the default choice because it preserves formatting on every device and most ATS platforms parse it well — just make sure the text is selectable, not a scanned image. Send Word only when a job portal or recruiter explicitly asks for .docx. Whatever the format, avoid photo-heavy or design-heavy files that parsing tools cannot read.

Google Docs, Microsoft Word, and Canva offer quick ready-made layouts, while many developers prefer building a software engineer resume on Overleaf for its clean LaTeX output and version control. Whichever source you pick, make sure the template is single-column, ATS-readable, and easy to edit. Remember, a template only fixes the layout — shortlisting still depends on the impact and relevance of your content.

With no full-time experience, projects carry the resume: two or three strong projects with tech stack, GitHub links, and measurable outcomes. Add internships, hackathon wins, competitive programming profiles such as LeetCode or Codeforces, grouped technical skills, and education with CGPA if it is strong. Keep it strictly to one page, and skip objective statements and irrelevant coursework.