Technology
18 min read
Why load balancers exist, how they spread traffic across servers, and what makes that possible: stateless services. Covers Layer 4 versus Layer 7, reverse proxies, round robin, weighted, least connections and hashing, health checks, draining, sticky sessions, redundancy of the load balancer itself, and autoscaling.
Technology
15 min read
Turn request rates into the numbers that shape an architecture: storage per day and per year with replication and retention, ingress and egress bandwidth in Gbps, cache memory from the working set, database write limits, and a first server count with headroom and zone failure. Includes a full worked example and a calculator.
Technology
16 min read
Capacity estimation from absolute basics: units and powers of two, seconds in a day, and the funnel from total users to MAU, DAU, requests per day, average QPS and peak QPS. Includes peak factors you can derive, read and write splits, fan-out, three worked examples and a small calculator.
Technology
17 min read
When should a caller wait for an answer, and when should work happen later? Learn the costs and benefits of synchronous calls and asynchronous processing, the patterns for returning results later (202 and status polling, webhooks, push), and how to choose between short polling, long polling, Server-Sent Events, WebSockets and mobile push.
Technology
19 min read
Design APIs that clients can rely on: resources and URLs, HTTP methods and which are safe to retry, status codes, validation, error formats, cursor pagination, filtering, idempotency keys, rate-limit responses, versioning, and when gRPC or GraphQL fit better than REST.
Technology
17 min read
Follow one request from a phone to a database and back: DNS lookup, TCP and TLS handshakes, HTTP, the edge, the load balancer, the application and the data stores. Learn where the time goes, why round trips and distance dominate latency, and where requests fail.
Technology
19 min read
How to turn a vague prompt such as "design a photo app" into requirements you can design for: functional requirements, clarifying questions, and non-functional requirements stated as numbers, including latency percentiles, throughput, availability nines, durability and consistency.
Technology
18 min read
What system design actually is, why interviews test it, the components you will meet and the problem each one solves, and the seven-phase method this 45-article course uses for every design, from a first single-server app to large distributed systems.
CourseTechnology
6 min read
A free, 45-article course that takes you from basic web and backend ideas to designing and defending real systems in SDE-1 and SDE-2 interviews. It teaches a repeatable method (requirements, estimation, APIs, data, baseline, scaling, hardening), the building blocks and distributed-systems fundamentals behind it, and 15 progressively harder case studies.
Technology
19 min read
How to prepare for campus placements and fresher hiring in India: aptitude rounds, online coding assessments with fast input and output, technical interviews, CS fundamentals, explaining trade-offs, debugging under pressure and discussing projects honestly.
Technology
18 min read
A realistic week-by-week plan for working through this course around college or a job: what to learn, implement, practise and revise each week, with timed sessions, mock interviews, a spaced-revision schedule, and lighter and more intensive alternatives.
Technology
24 min read
Build a small, complete Java project that uses many data structures together: a practice tracker with spaced-repetition reviews, undo, title autocomplete and a prerequisite-based study order. Requirements, design, milestones, test cases and extension ideas, with no paid services.
Technology
23 min read
A step-by-step routine for coding interviews: clarify, work examples, state a brute force, optimize, agree on a plan, code, test and analyze. Includes a full sample dialogue, advice on getting unstuck, and checklists you can use in mock interviews.
Technology
22 min read
What to do when prefix sums are not enough: Fenwick and segment trees for range queries with updates (optional depth), and disjoint set union with path compression and union by size for connectivity, cycles and Kruskal's algorithm (the part worth knowing).
Technology
19 min read
A trie stores words so that shared prefixes share nodes, making insert, exact search and prefix search take time proportional to the word length. Build one in Java, compare array and map nodes, and use it for autocomplete, wildcards and shortest-prefix replacement.
Technology
21 min read
Apply the six-step DP workflow to climbing stairs, house robber, grid paths and the longest common subsequence. For each: state, transition, base cases, evaluation order, complexity and why it is correct, with full tables and reconstruction.
Technology
20 min read
Dynamic programming is recursion that remembers. Learn overlapping subproblems and optimal substructure, memoization and tabulation on Fibonacci, a repeatable six-step formulation workflow, and the coin change problem that greedy cannot solve.
Technology
24 min read
When BFS is enough and when it is not, Dijkstra's algorithm with a priority queue and its non-negative-weight limit, a glance at Bellman-Ford, and topological sorting with Kahn's algorithm and DFS for dependency order, including how to detect impossible orders.
