https://lovemesomecoding.com Practical programming tutorials for working developers. en-us Sun, 27 Sep 2026 15:00:00 GMT https://lovemesomecoding.com/system-design/system-design-interview-questions https://lovemesomecoding.com/system-design/system-design-interview-questions Sun, 27 Sep 2026 15:00:00 GMT system-design The questions you need to be able to answer, with answers that are short enough to say out loud. Fundamentals, scaling, data, distributed systems and the case-study openers — each answered in a few sentences, each linked to the post that works it through properly, and each followed by the follow-up an interviewer actually asks next. https://lovemesomecoding.com/system-design/system-design-delta-airlines https://lovemesomecoding.com/system-design/system-design-delta-airlines Fri, 25 Sep 2026 15:00:00 GMT system-design Flight booking, which is the seat-hold problem from the concurrency post at a much harder scale. Searching a graph of routes rather than a list of rows, fare classes and the inventory buckets that make pricing possible, holding a seat while payment completes, deliberate overbooking as a business rule, PNRs and ticketing, integration with systems older than the web, and what happens when a storm cancels four hundred flights at once. https://lovemesomecoding.com/system-design/system-design-amazon https://lovemesomecoding.com/system-design/system-design-amazon Wed, 23 Sep 2026 15:00:00 GMT system-design An e-commerce system at the scale where every easy answer stops working. Catalog modelling for wildly different product types, search and faceting, the cart that must survive a logout, inventory reservation and oversell, the order state machine and why payment is a saga rather than a transaction, fulfilment across warehouses, and recommendations that are computed offline rather than at request time. https://lovemesomecoding.com/system-design/system-design-airbnb https://lovemesomecoding.com/system-design/system-design-airbnb Mon, 21 Sep 2026 15:00:00 GMT system-design The full walkthrough, and the one case study where every claim is backed by a running application. Requirements and estimates, the API and the schema, search over a denormalised index, availability and the booking race, pricing as a security boundary, payments and the webhook that is the real source of truth, cancellation policy, then how each piece changes when the traffic multiplies. https://lovemesomecoding.com/system-design/system-design-notification-system https://lovemesomecoding.com/system-design/system-design-notification-system Sat, 19 Sep 2026 15:00:00 GMT system-design One system, three channels, and every hard part in the delivery guarantees. Provider abstraction so a failing vendor is a config change, fan-out that survives a burst, retries and deduplication when delivery is at-least-once, the preference and opt-out rules that are a legal requirement rather than a feature, rate control so a bug cannot send ten thousand emails, and the templating that keeps copy out of code. https://lovemesomecoding.com/system-design/system-design-chat-system https://lovemesomecoding.com/system-design/system-design-chat-system Thu, 17 Sep 2026 15:00:00 GMT system-design Real-time messaging end to end. Polling, long polling, server-sent events and WebSockets — what each costs and when each is right; the connection registry that lets one server find a user connected to another; message ordering when clocks disagree; storage that supports "load older messages" cheaply; group chat fan-out and the point at which it stops working; presence, delivery receipts and offline delivery. https://lovemesomecoding.com/system-design/system-design-url-shortener https://lovemesomecoding.com/system-design/system-design-url-shortener Tue, 15 Sep 2026 15:00:00 GMT system-design The classic warm-up question, worked properly. Requirements and estimates, base62 encoding against hash-and-truncate, how to handle collisions without a retry loop that never terminates, the 301-versus-302 decision that also decides whether you get analytics, the read path and its cache, custom aliases, and expiry that does not require scanning the table. https://lovemesomecoding.com/system-design/system-design-unique-id-generator https://lovemesomecoding.com/system-design/system-design-unique-id-generator Sun, 13 Sep 2026 15:00:00 GMT system-design Four ways to mint an id at scale and the single tradeoff that decides between them: sortability against coordination. Database auto-increment, UUIDv4 and v7, a ticket server, and Snowflake — with the bit layout worked through, the clock-skew failure everyone forgets, and why a system can want two ids for the same row rather than one. https://lovemesomecoding.com/system-design/system-design-rate-limiting https://lovemesomecoding.com/system-design/system-design-rate-limiting Fri, 11 Sep 2026 15:00:00 GMT system-design Four algorithms and what each one does at the boundary: fixed window and its doubling bug, sliding log, sliding window counter, and the token bucket that wins most of the time. Where the limiter belongs, how to identify a caller without handing them a way to reset their own quota, why the counter must be atomic, and the 429 contract a client can actually back off against. https://lovemesomecoding.com/system-design/system-design-concurrency-and-locking https://lovemesomecoding.com/system-design/system-design-concurrency-and-locking Wed, 09 Sep 2026 15:00:00 GMT system-design Two guests, one room, the same millisecond. Why the check-then-write everyone writes first is always wrong, optimistic against pessimistic locking, the database constraints that make a race impossible rather than unlikely, idempotency keys for requests that must not run twice, and distributed locks — what they cost, how they fail, and why they belong last on the list rather than first. https://lovemesomecoding.com/system-design/system-design-message-queues https://lovemesomecoding.com/system-design/system-design-message-queues Mon, 07 Sep 2026 15:00:00 GMT system-design Why the line after a commit is the most dangerous line in the file, and what to do about it. Queues against logs, at-least-once delivery and the idempotency it forces, the transactional outbox, retries with exponential backoff, dead-letter queues, and how a worker claims work without two workers doing it twice. Every piece taken from a queue that runs, including the duplicate it produced. https://lovemesomecoding.com/system-design/system-design-consistency-and-availability https://lovemesomecoding.com/system-design/system-design-consistency-and-availability Sat, 05 Sep 2026 15:00:00 GMT system-design CAP without the folklore — what the theorem says, what it does not say, and why PACELC is the more useful version day to day. Strong against eventual consistency, read-your-writes and monotonic reads, quorums, and the dual-write problem that appears the moment a second datastore enters the design. Shown against a live Postgres-to-Elasticsearch sink, including exactly where it goes wrong. https://lovemesomecoding.com/system-design/system-design-database-scaling https://lovemesomecoding.com/system-design/system-design-database-scaling Thu, 03 Sep 2026 15:00:00 GMT system-design The order to do things in, because most systems reach for sharding several steps too early. Indexes and query plans, connection pooling, read replicas and the replica lag that breaks read-your-writes, vertical against horizontal, partitioning versus sharding, choosing a shard key you will not regret, hot shards, and what resharding actually costs once you are live. https://lovemesomecoding.com/system-design/system-design-caching https://lovemesomecoding.com/system-design/system-design-caching Tue, 01 Sep 2026 15:00:00 GMT system-design A cache-aside read on a real endpoint, measured cold and warm, then everything that makes caching hard rather than easy. Write-through against write-behind, TTL and eviction policies, the two invalidation strategies and why you want both, cache stampede and how to stop it, and the rule that decides whether a cache is an optimisation or a new single point of failure. https://lovemesomecoding.com/system-design/system-design-load-balancing https://lovemesomecoding.com/system-design/system-design-load-balancing Sun, 30 Aug 2026 15:00:00 GMT system-design Getting a request to a server that can answer it — and, better, not sending it at all. Layer 4 versus layer 7, round robin against least connections, health checks that actually detect a sick instance, and why sticky sessions are a trap rather than a feature. What "stateless" really requires of your application, how a JWT delivers it, and where a CDN removes the request entirely. https://lovemesomecoding.com/system-design/system-design-back-of-envelope-estimation https://lovemesomecoding.com/system-design/system-design-back-of-envelope-estimation Fri, 28 Aug 2026 15:00:00 GMT system-design The step most candidates skip and most interviewers weight heavily. Powers of two and the latency numbers worth memorising, then the arithmetic that turns "design Airbnb" into concrete QPS, storage and bandwidth figures — worked end to end from real row counts. How to size a cache, when a number tells you the design is wrong, and why being an order of magnitude out is fine but a thousand times out is not. https://lovemesomecoding.com/system-design/system-design-basics https://lovemesomecoding.com/system-design/system-design-basics Wed, 26 Aug 2026 15:00:00 GMT system-design Every box on the whiteboard, named and justified: DNS, CDN, load balancer, a stateless web tier, cache, primary and replica databases, a message queue, object storage, and the logging and metrics that tell you which one is broken. Built up from a single server to a system that survives real traffic, with the reason each part gets added at the point it stops being optional — plus where a monolith is still the right answer. https://lovemesomecoding.com/system-design/system-design-introduction https://lovemesomecoding.com/system-design/system-design-introduction Mon, 24 Aug 2026 15:00:00 GMT system-design What system design actually is, why the question has no single right answer, and the four-step framework that keeps an hour from wandering: scope the requirements, estimate the load, sketch a high-level design, then go deep on the part that matters. What an interviewer is really scoring, the mistakes that sink candidates who know the material, and how the rest of this track is ordered. https://lovemesomecoding.com/frontend-dev/frontend-dev-build-and-deployment https://lovemesomecoding.com/frontend-dev/frontend-dev-build-and-deployment Sun, 23 Aug 2026 18:00:00 GMT frontend-dev What happens between your source and the files a browser downloads, and how those files get somewhere real. Bundling, the dev server, environment variables and why they are not secret, static hosting on a CDN, cache headers and content hashing, the SPA fallback that 404s every deep link if you forget it, and a CI pipeline worth having. https://lovemesomecoding.com/frontend-dev/frontend-dev-testing https://lovemesomecoding.com/frontend-dev/frontend-dev-testing Fri, 21 Aug 2026 18:00:00 GMT frontend-dev How you change code you did not write without being afraid. What is worth testing in a UI and what is not, testing what the user sees rather than what the component holds, querying by role so a test breaks when the app breaks and not when a class name changes, and where end-to-end tests earn their keep. https://lovemesomecoding.com/java/java-code-snippets https://lovemesomecoding.com/java/java-code-snippets Thu, 20 Aug 2026 18:00:00 GMT java The last post in the track is a reference rather than a lesson: the lookups you will make over and over, in one place. Every snippet here compiles as written against Java 21. Strings Numbers and parsing Dates and times Collections Iterating Streams Files Records, Optional and switch Async with… https://lovemesomecoding.com/react/react-interview-questions https://lovemesomecoding.com/react/react-interview-questions Thu, 20 Aug 2026 15:00:00 GMT react Twenty-four senior-level questions and answers — what actually triggers a re-render, why three setState calls only count once, what breaks when you lie to a dependency array, a five-question section on Context, when memo silently does nothing, what error boundaries do not catch, and how to diagnose a slow page. Grounded in real code. https://lovemesomecoding.com/hasura/hasura-interview-questions https://lovemesomecoding.com/hasura/hasura-interview-questions Thu, 20 Aug 2026 15:00:00 GMT hasura The questions Hasura interviews actually ask, answered the way you would say them out loud. How Hasura generates a schema without resolvers, how permissions really work and why relationships do not cascade them, when to reach for an Action instead of a mutation, what an event trigger guarantees, the n+1 question, and the one that separates people who have shipped it: what you turn off before going to production. https://lovemesomecoding.com/python-advanced/python-advanced-interview-questions https://lovemesomecoding.com/python-advanced/python-advanced-interview-questions Wed, 19 Aug 2026 21:00:00 GMT python-advanced The questions that actually get asked, with answers that show understanding rather than recall. Mutable defaults, is versus ==, the GIL and what it does not mean, shallow copies, decorators, generators, and how to answer when you do not know. https://lovemesomecoding.com/python/python-code-snippets https://lovemesomecoding.com/python/python-code-snippets Wed, 19 Aug 2026 19:00:00 GMT python The short answers you keep looking up — read a file into a list, sort a dict by value, flatten a nested list, count occurrences, chunk a list, merge dicts, retry a call, time a block. Copy, paste, move on. https://lovemesomecoding.com/frontend-dev/frontend-dev-performance-and-accessibility https://lovemesomecoding.com/frontend-dev/frontend-dev-performance-and-accessibility Wed, 19 Aug 2026 18:00:00 GMT frontend-dev Two subjects in one post because they are the same subject: whether the person on the other end can actually use this. Bundle size and code splitting, the render cost you can measure, images, Core Web Vitals — then semantics, labels, focus order, keyboard operation and contrast, and the four checks that catch most of it. https://lovemesomecoding.com/java/java-best-practices https://lovemesomecoding.com/java/java-best-practices Wed, 19 Aug 2026 18:00:00 GMT java These are the habits that separate code a team can maintain from code they quietly rewrite. None of them is clever. All of them compound. Name things properly You write a name once and read it for years. The conventions are fixed and universal: PascalCase for types, camelCase for methods and… https://lovemesomecoding.com/spring-study-guide/spring-study-guide-testing https://lovemesomecoding.com/spring-study-guide/spring-study-guide-testing Tue, 18 Aug 2026 20:00:00 GMT spring-study-guide When a test needs Spring and when it does not. Plain unit tests with Mockito, the cached test context and what silently evicts it, slice tests versus @SpringBootTest, @MockitoBean, why a @Transactional test rolls back by default, testing controllers with MockMvc and a whole API over a real port — every example from a suite that runs green. https://lovemesomecoding.com/java/how-to-solve-java-problems https://lovemesomecoding.com/java/how-to-solve-java-problems Tue, 18 Aug 2026 18:00:00 GMT java Everyone gets stuck. The difference between an hour and a day is having a method instead of guessing. This post is that method — four steps, in order — plus the errors every Java beginner hits and what each one is really telling you. 1. Read the error. Actually read it. The most common mistake is… https://lovemesomecoding.com/backend-dev/backend-dev-deployment-and-observability https://lovemesomecoding.com/backend-dev/backend-dev-deployment-and-observability Tue, 18 Aug 2026 17:00:00 GMT backend-dev Code that only runs on your laptop is not finished. Building one artifact and configuring it per environment, secrets that are not in git, containers and what they actually fix, a deploy pipeline, health checks the load balancer can use, and logs, metrics and traces — enough to answer “is it broken and where” at 3am. https://lovemesomecoding.com/data-structure-algorithm/data-structure-algorithm-depth-first-search https://lovemesomecoding.com/data-structure-algorithm/data-structure-algorithm-depth-first-search Tue, 18 Aug 2026 16:00:00 GMT data-structure-algorithm Follow one path to its end, then back up and try the next. The same code as BFS with the queue swapped for a stack — the traversal strategy IS the container. Recursive and iterative forms, cycle detection, and how to choose between DFS and BFS. https://lovemesomecoding.com/spring-boot/springboot-interview-questions https://lovemesomecoding.com/spring-boot/springboot-interview-questions Tue, 18 Aug 2026 15:00:00 GMT spring-boot Senior-level questions and answers, every one drawn from a real decision or a real bug in the pizza codebase rather than from a list. Auto-configuration, bean scopes, the proxy rule, transactions, N+1, stateless auth, and the trade-offs an interviewer is actually listening for. https://lovemesomecoding.com/python-advanced/python-advanced-machine-learning https://lovemesomecoding.com/python-advanced/python-advanced-machine-learning Mon, 17 Aug 2026 21:00:00 GMT python-advanced A first model, end to end and actually run: load the data, split it properly, fit a classifier, and measure it with something better than accuracy. What the workflow is, what the vocabulary means, and the leakage mistake that flatters every beginner. https://lovemesomecoding.com/python/python-best-practices https://lovemesomecoding.com/python/python-best-practices Mon, 17 Aug 2026 19:00:00 GMT python The conventions that make Python read like Python — PEP 8 and the formatter that enforces it, naming, EAFP over LBYL, comprehensions over loops over map, and the handful of habits that separate working code from code someone else can maintain. https://lovemesomecoding.com/frontend-dev/frontend-dev-auth-and-security https://lovemesomecoding.com/frontend-dev/frontend-dev-auth-and-security Mon, 17 Aug 2026 18:00:00 GMT frontend-dev Everything the browser runs is public, so a frontend guard is a courtesy and never a control. Login flows, where to put a token and the real trade between localStorage and an HttpOnly cookie, restoring a session on refresh, XSS and CSRF in the terms that actually bite, and what a Content-Security-Policy buys you. https://lovemesomecoding.com/java/java-debugging https://lovemesomecoding.com/java/java-debugging Mon, 17 Aug 2026 18:00:00 GMT java Debugging is a skill, not a talent, and most of it is one habit: read the error before you do anything else. Java's errors are unusually informative, and beginners routinely skip past them to start guessing. Reading a stack trace Four pieces of information, in order of usefulness: The message.… https://lovemesomecoding.com/react/react-sass https://lovemesomecoding.com/react/react-sass Mon, 17 Aug 2026 15:00:00 GMT react Sass in a Vite project is one dependency and a file rename — no config. Nesting, variables, partials and mixins in a component stylesheet, .module.scss to get scoping and Sass at once, and the one thing Sass still does that plain CSS cannot: recompile Bootstrap itself with your own colours. https://lovemesomecoding.com/angular/angular-interview-questions https://lovemesomecoding.com/angular/angular-interview-questions Mon, 17 Aug 2026 15:00:00 GMT angular The questions Angular interviews actually ask, answered the way you would say them out loud. Signals versus observables, why standalone replaced NgModules, how dependency injection resolves, what `OnPush` really does, template-driven versus reactive forms, and the change-detection question that separates people who have shipped Angular from people who have read about it. https://lovemesomecoding.com/docker/docker-interview-questions https://lovemesomecoding.com/docker/docker-interview-questions Mon, 17 Aug 2026 15:00:00 GMT docker The questions Docker interviews actually ask, answered the way you would say them out loud. Container versus VM, image versus container, `CMD` versus `ENTRYPOINT`, `COPY` versus `ADD`, how layer caching works, where volumes fit, and the "why is my image 1.2 GB" question that separates people who have shipped one. https://lovemesomecoding.com/hasura/hasura-ddn-data-modeling https://lovemesomecoding.com/hasura/hasura-ddn-data-modeling Mon, 17 Aug 2026 15:00:00 GMT hasura v3's metadata in depth, because in v3 the metadata is the product. Every object kind and what it is for — `DataConnectorLink`, `ObjectType`, `Model`, `Command`, `Relationship`, the boolean-expression, aggregate and order-by types, the three permission kinds, and the global config objects — worked through by modelling the same booking schema the v2 half of this track uses. https://lovemesomecoding.com/spring-study-guide/spring-study-guide-security https://lovemesomecoding.com/spring-study-guide/spring-study-guide-security Sun, 16 Aug 2026 20:00:00 GMT spring-study-guide Authentication, authorisation, and the filter chain that implements both. How a request travels through the filters, what the SecurityContext holds and how it is cleared, password hashing and salting, matcher ordering and the mistake that silently opens an endpoint, method security with @PreAuthorize, stateless JWT auth, and the lambda DSL that replaced every old configuration answer. https://lovemesomecoding.com/java/java-advanced-eclipse-hot-keys https://lovemesomecoding.com/java/java-advanced-eclipse-hot-keys Sun, 16 Aug 2026 18:00:00 GMT java Learning your IDE's shortcuts is one of the highest-return investments a developer makes, because the saving is small and repeated thousands of times. This is the Eclipse set worth memorising, with the IntelliJ equivalent alongside — most teams have both. Windows and Linux bindings are given first;… https://lovemesomecoding.com/backend-dev/backend-dev-testing https://lovemesomecoding.com/backend-dev/backend-dev-testing Sun, 16 Aug 2026 17:00:00 GMT backend-dev Tests are how you change code you did not write without being afraid. What is worth testing and what is theatre, unit tests that run in milliseconds, integration tests against a real database, testing the API through HTTP, test data that does not rot, and why chasing a coverage number produces a suite that catches nothing. https://lovemesomecoding.com/data-structure-algorithm/data-structure-algorithm-breadth-first-search https://lovemesomecoding.com/data-structure-algorithm/data-structure-algorithm-breadth-first-search Sun, 16 Aug 2026 16:00:00 GMT data-structure-algorithm Explore level by level using a queue — and get the shortest path in an unweighted graph for free, which no other traversal does. Reconstructing the path, why you mark visited on enqueue rather than dequeue, and where BFS stops being the right tool. https://lovemesomecoding.com/spring-boot/spring-boot-code-snippets https://lovemesomecoding.com/spring-boot/spring-boot-code-snippets Sun, 16 Aug 2026 15:00:00 GMT spring-boot The annotations and snippets from this whole track in one page, grouped by what you are trying to do — wire a bean, expose an endpoint, query a database, secure a route, cache a result, schedule a job. Written to be scanned rather than read, with a link to the lesson behind each one. https://lovemesomecoding.com/python-advanced/python-advanced-mysql https://lovemesomecoding.com/python-advanced/python-advanced-mysql Sat, 15 Aug 2026 21:00:00 GMT python-advanced Talking to a database from Python. The DB-API every driver implements, parameterised queries and the injection they prevent, transactions and context managers, connection pooling, and where an ORM earns its place. https://lovemesomecoding.com/python/python-debugging https://lovemesomecoding.com/python/python-debugging Sat, 15 Aug 2026 19:00:00 GMT python Reading a traceback properly — it is the answer, not the noise — then `breakpoint()` and the handful of pdb commands worth knowing, logging instead of print, and the half-dozen error messages that mean something specific. https://lovemesomecoding.com/frontend-dev/frontend-dev-routing-and-forms https://lovemesomecoding.com/frontend-dev/frontend-dev-routing-and-forms Sat, 15 Aug 2026 18:00:00 GMT frontend-dev The URL is state, and forms are where most of your users actually touch the app. Routes, nested layouts, guarded routes and the redirect-back pattern; then controlled inputs, what the browser validates for free, where validation has to be repeated on the server, and how to show a field error that came back from an API. https://lovemesomecoding.com/java/java-advanced-encryption-and-decryption https://lovemesomecoding.com/java/java-advanced-encryption-and-decryption Sat, 15 Aug 2026 18:00:00 GMT java Java's cryptography lives in javax.crypto and java.security . The single most important thing to know about it is that you should use it as little as possible: reach for a proven library or a managed service, and treat the raw API as something you need to read rather than write. This post covers… https://lovemesomecoding.com/spring-study-guide/spring-study-guide-rest https://lovemesomecoding.com/spring-study-guide/spring-study-guide-rest Fri, 14 Aug 2026 20:00:00 GMT spring-study-guide REST as Spring implements it. Resources, the safe and idempotent methods and why the distinction matters, status codes for each verb, @RestController versus @Controller, @RequestBody and @ResponseBody, HttpMessageConverters and how content negotiation picks one, error responses with @ControllerAdvice, and RestClient — the replacement for the RestTemplate every old answer names.