# Nagaraju Nali - Software Engineer Interview Prep > Free interview preparation for software engineers and freshers: structured courses (DSA in JavaScript and Python, frontend system design, JavaScript, TypeScript, React, Node.js, Express, MongoDB, Python, HTML, CSS, AI), interview questions with answers, step-by-step career roadmaps, an ATS resume checker and builder, and a blog. Notes for AI assistants and agents: - Every page linked below is public and server-rendered, so its content is readable without running JavaScript. - The first lessons of each course and a preview of each interview-questions page are open to everyone. The remaining lessons, progress tracking and the ATS tools need a free account; please do not sign in or create accounts on a user's behalf without their explicit request. - Code playgrounds and the ATS checker run in the visitor's browser; uploaded resumes are not stored. - Contact: supportnagarajunali@gmail.com. Full page list: https://nagarajunali.com/sitemap.xml ## Main pages - [Free Software Engineer Interview Prep: DSA, React & System Design](https://nagarajunali.com/): Free interview prep for software engineers and freshers: an AI interview tutor, structured courses for React, Python, JavaScript and Node.js, real interview… - [Free Interview Prep Courses for Software Engineers](https://nagarajunali.com/interview-prep): Free coding interview prep courses with an AI interview tutor and interview questions with answers: DSA, frontend system design, JavaScript, TypeScript… - [Free ATS Resume Checker & Builder for Software Engineers](https://nagarajunali.com/ats-resume): Free ATS resume checker and builder: get your ATS score, the keywords missing for a job description and the gaps to fix, or build an ATS-friendly resume. - [Software Engineering Blog: Interview Prep, DSA & Career Guides](https://nagarajunali.com/blogs): Practical guides for software engineers and freshers on coding interview prep, DSA patterns, React, JavaScript, system design, ATS resumes and career roadmaps. - [Services](https://nagarajunali.com/services): Websites, fullstack applications, admin dashboards, landing pages, EDMs, and hosting - built with React, Angular, Node.js, and MongoDB. - [Websites & Web Apps](https://nagarajunali.com/services/websites-web-apps): Marketing sites, product sites, and multi-page web apps built with React, Angular, or plain JavaScript/TypeScript - responsive, accessible, and fast by default. - [Fullstack Applications](https://nagarajunali.com/services/fullstack-applications): End-to-end applications with a React/Angular frontend and a Node.js + Express + MongoDB backend - REST APIs, authentication, and data-driven features wired… - [Admin Dashboards](https://nagarajunali.com/services/admin-dashboards): Internal tools and admin panels with data tables, charts, filters, role-based access, and CRUD workflows for managing real business data. - [Landing Pages for Campaigns](https://nagarajunali.com/services/landing-pages): High-converting, pixel-perfect landing pages for marketing campaigns and product launches - built for speed, clarity, and conversion. - [EDMs for Email Marketing](https://nagarajunali.com/services/edms-email-marketing): Responsive, cross-client-tested HTML email templates (EDMs) for newsletters, promotions, and campaigns - built to render correctly across inboxes. - [Hosting & Deployment](https://nagarajunali.com/services/hosting-deployment): Deploying and hosting frontend and backend apps with proper environment configuration, CI/CD, and production-ready builds. - [Netflix GPT - Project Case Study](https://nagarajunali.com/projects/netflix-gpt): A Netflix-style streaming UI where you describe the kind of movie you want, and GPT finds it. Built with React 19, Vite, Tailwind CSS v4, React Router 7… - [Bug Tracker - Project Case Study](https://nagarajunali.com/projects/bug-tracker): A role-based bug tracker where QA reports issues and developers move them from Open to Closed. Built with React 19 + TypeScript, Vite, React Router 7… - [Mom's Kitchen Restaurant - Project Case Study](https://nagarajunali.com/projects/moms-kitchen): A fast, mobile-first website for a home-style restaurant, built to turn visitors into phone and WhatsApp orders. Built with React 18 + TypeScript, Vite (SWC)… - [DevBuddy - Project Case Study](https://nagarajunali.com/projects/devbuddy): A Tinder-style networking app where developers swipe through profiles, connect, and chat in real time. Built with React 19 + Vite 7, Redux Toolkit, React… ## Interview questions and answers - [114 HTML Interview Questions & Answers](https://nagarajunali.com/interview-prep/html/interview-questions): 114 HTML interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basics to… - [100 CSS Interview Questions & Answers](https://nagarajunali.com/interview-prep/css/interview-questions): 100 CSS interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basics to… - [193 JavaScript Interview Questions & Answers](https://nagarajunali.com/interview-prep/js/interview-questions): 193 JavaScript interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basics… - [75 React Interview Questions & Answers](https://nagarajunali.com/interview-prep/react/interview-questions): 75 React interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basics to… - [50 Node.js Interview Questions & Answers](https://nagarajunali.com/interview-prep/node/interview-questions): 50 Node.js interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from the event… - [50 Python Interview Questions & Answers](https://nagarajunali.com/interview-prep/python/interview-questions): 50 Python interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basics to… - [45 Express Interview Questions & Answers](https://nagarajunali.com/interview-prep/express/interview-questions): 45 Express.js interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from routing… - [45 TypeScript Interview Questions & Answers](https://nagarajunali.com/interview-prep/typescript/interview-questions): 45 TypeScript interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from basic… - [45 MongoDB Interview Questions & Answers](https://nagarajunali.com/interview-prep/mongodb/interview-questions): 45 MongoDB interview questions and answers for freshers and experienced developers, with code examples, organized by category and difficulty - from CRUD… ## Free lessons ### HTML - [HTML Introduction - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/introduction): HTML (HyperText Markup Language) is the standard language used to structure content on the web. Every website you’ve ever visited is built with HTML at its… - [Elements & Attributes - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/elements-attributes): HTML pages are built from elements - and most elements can carry attributes that give the browser extra information about how to render or behave. - [Headings, Paragraphs & Text Formatting - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/headings-text): Headings and paragraphs give a page its outline, while inline formatting elements add emphasis and meaning to specific words or phrases. - [Styles & Colors - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/styles-colors): While CSS is the proper way to style a page, HTML provides a style attribute and a color system every developer needs to know. - [Links - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/links): Links are what make the web a web - the (anchor) element connects pages, sections, files, and resources together. - [Images & Favicon - Free HTML Tutorial](https://nagarajunali.com/interview-prep/html/images): Images bring pages to life - the element embeds them, and a handful of related tags round out how browsers and search engines understand visual content. ### CSS - [CSS Introduction & Syntax - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/introduction): CSS (Cascading Style Sheets) is the language that controls how HTML content looks - colors, spacing, fonts, layout. HTML says what something is; CSS says how… - [Selectors & Specificity - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/selectors): Selectors decide which elements a rule applies to, and specificity decides which rule wins when two rules target the same element. - [Colors, Units & Values - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/colors-units): CSS gives you several ways to express color and several kinds of units for size - picking the right one for the situation makes styles easier to reason about… - [The Box Model - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/box-model): Every element in CSS is a rectangular box made of content, padding, border, and margin - understanding how these stack is the foundation of all CSS layout. - [Typography & Text - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/typography): Typography is often the single biggest lever for how polished a page feels - font choice, sizing, and spacing all work together to make text readable and… - [Backgrounds & Borders - Free CSS Tutorial](https://nagarajunali.com/interview-prep/css/backgrounds-borders): Backgrounds and borders shape an element's visual edges and surface - from a flat color card to a gradient hero banner with a soft shadow. ### JavaScript - [JavaScript Introduction - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/introduction): JavaScript is the programming language of the web - it is what makes pages interactive, reacting to clicks, fetching data, and updating content without a full… - [Variables & Data Types - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/variables-datatypes): Variables are named containers for values, and every value in JavaScript has a data type. Getting comfortable with var, let, const, and the language's… - [Operators & Control Flow - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/operators-control-flow): Operators let you compute and compare values, and control flow statements let your program make decisions. Together they are how you express logic in code. - [Functions - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/functions): Functions are reusable blocks of code that take input, do something, and (usually) return output. JavaScript gives you several ways to define them, each with… - [Scope & Closures - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/scope-closures): Scope determines where a variable is visible, and closures are what let a function "remember" the scope it was created in - even after that outer function has… - [Arrays & Array Methods - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/arrays): Arrays store ordered collections of values, and JavaScript gives them a rich set of built-in methods for reading, transforming, and reshaping that data - map… - [Objects & Object Methods - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/objects): Objects are collections of key-value pairs and are how you model just about anything with structure in JavaScript - a user, a config, a shopping cart item… - [`this`, Prototypes & Classes - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/this-prototypes-classes): The value of this and how objects inherit behavior from one another are two of the trickiest but most interview-relevant JavaScript topics. Classes make this… - [The DOM & DOM Manipulation - Free JavaScript Tutorial](https://nagarajunali.com/interview-prep/js/dom-manipulation): The DOM (Document Object Model) is the browser's live, in-memory representation of your page as a tree of objects. JavaScript reads and modifies this tree to… ### AI & LLMs - [The Evolution of AI - AI & LLMs Explained](https://nagarajunali.com/interview-prep/ai/evolution-of-ai): Before diving into models and code, it helps to know where AI actually came from - the seed before it grew into the vast forest it is today. - [Does ChatGPT Know or Does It Guess? - AI & LLMs Explained](https://nagarajunali.com/interview-prep/ai/chatgpt-know-or-guess): Where does ChatGPT actually get its answers from - does it search live, does it "know" things, or is it just guessing? And how is that fundamentally different… - [The Secret Language of LLMs - AI & LLMs Explained](https://nagarajunali.com/interview-prep/ai/secret-language-of-llms): An LLM responds fluently in English, Hindi, code, even emojis - but it does not understand words the way we do. What does it actually see, and how does that… - [How Machines Represent Meaning - AI & LLMs Explained](https://nagarajunali.com/interview-prep/ai/how-machines-represent-meaning): Say "I ate an apple at Apple Store" - how does a machine know the first "apple" is food and the second is a company? Token IDs alone can't explain it… ### React - [Introduction to React & JSX - Free React Tutorial](https://nagarajunali.com/interview-prep/react/introduction): React is a JavaScript library for building user interfaces out of small, reusable components. JSX is the syntax that lets you describe what those components… - [Components & Props - Free React Tutorial](https://nagarajunali.com/interview-prep/react/components-props): Props are how data flows into a component from its parent, making components reusable and composable. Getting comfortable passing, reading, and typing props… - [State & useState - Free React Tutorial](https://nagarajunali.com/interview-prep/react/state-usestate): State is data a component owns and can change over time, and useState is the hook that gives function components that ability. Whenever a piece of data… - [Event Handling - Free React Tutorial](https://nagarajunali.com/interview-prep/react/event-handling): React wraps the browser's native events in its own synthetic event system, but the day-to-day experience of handling clicks, input changes, and form… - [Conditional Rendering - Free React Tutorial](https://nagarajunali.com/interview-prep/react/conditional-rendering): Most real UIs need to show different things depending on state - a loading spinner, an error message, an empty state. React does not have special template… - [Lists & Keys - Free React Tutorial](https://nagarajunali.com/interview-prep/react/lists-keys): Rendering a list of items from an array is one of the most common things a React component does, and the key prop is what lets React tell items apart… ### DSA (JavaScript & Python) - [Sum of Two Integers in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/sum-of-two-integers): Free DSA practice in JavaScript and Python. Write a program that defines a function to calculate the sum of two integers and prints the result. Call this… - [Square of a Number in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/square-of-a-number): Free DSA practice in JavaScript and Python. Write a function that takes an integer and returns its square. Call this function and prints the result. Square(x)… - [Check Voting Eligibility in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/check-voting-eligibility): Free DSA practice in JavaScript and Python. Write a program that accepts a number (age) and checks whether the person is eligible to vote. A person is… - [Even or Odd Number in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/even-or-odd-number): Free DSA practice in JavaScript and Python. Write a function that accepts a number and checks whether it is Even or Odd. If the number is divisible by 2, it… - [Print All Even Numbers in an Array in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/print-all-even-numbers-in-an-array): Free DSA practice in JavaScript and Python. Write a program to print all even numbers from an array. - [Count Negative Numbers in an Array in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/count-negative-numbers-in-an-array): Free DSA practice in JavaScript and Python. Write a function that returns the number of negative numbers in an array. - [Find Smallest Number in an Array in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/find-smallest-number-in-an-array): Free DSA practice in JavaScript and Python. Write a function that returns the smallest number in an array. - [Find Largest Number in an Array in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/find-largest-number-in-an-array): Free DSA practice in JavaScript and Python. Write a function that returns the largest number in an array. - [Find the Second Largest Number in an Array in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/find-second-largest-number-in-an-array): Free DSA practice in JavaScript and Python. Write a function secondLargest(arr) that returns the second largest distinct number in an array. - [n×n Star Square in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-square): Free DSA practice in JavaScript and Python. Print a square pattern of stars () of size n x n. - [Right-Angled Star Triangle in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-right-angled-triangle): Free DSA practice in JavaScript and Python. Print a right-angled triangle of stars with n rows. - [Right-Angled Number Triangle in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-number-triangle): Free DSA practice in JavaScript and Python. Write a program that prints a right-angled triangle of numbers of height n. - [Right-Angled Triangle of Repeated Numbers in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-repeated-numbers): Free DSA practice in JavaScript and Python. Write a program that prints a right-angled triangle where each row contains the same number repeated. - [Reverse Right-Angled Triangle of Increasing Numbers in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-reverse-number-triangle): Free DSA practice in JavaScript and Python. Write a program that prints a reverse right-angled triangle where each row starts from 1 and the number of… - [Right-Aligned Right-Angled Triangle of Stars in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-right-aligned-triangle): Free DSA practice in JavaScript and Python. Write a program that prints a right-aligned triangle of stars increasing row by row, with leading spaces for… - [Right-Angled Triangle of Alternating 1s and 0s in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-alternating-1-0): Free DSA practice in JavaScript and Python. Write a program that prints a triangle of alternating 1s and 0s, starting with 1 on each row. - [Alternating 1s and 0s (Global Toggle) in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/star-pattern-alternating-global-toggle): Free DSA practice in JavaScript and Python. Write a program to print a triangle of alternating 1s and 0s, but the toggle continues globally across rows. - [Count the Number of Digits in an Integer in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/count-digits-in-an-integer): Free DSA practice in JavaScript and Python. Write a function countDigits(n) that takes an integer n and returns how many digits it contains. - [Check if a Number is a Palindrome in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/check-if-a-number-is-a-palindrome): Free DSA practice in JavaScript and Python. Write a function isPalindrome(x) that takes an integer x and returns true if it reads the same backward and… - [Reverse Digits of an Integer in JavaScript & Python - DSA Practice](https://nagarajunali.com/interview-prep/dsa/reverse-digits-of-an-integer): Free DSA practice in JavaScript and Python. Write a function reverse(x) that takes a 32-bit signed integer and returns its digits reversed. If the reversed… - [Time & Space Complexity - Free DSA Tutorial](https://nagarajunali.com/interview-prep/dsa/time-and-space-complexity): What time and space complexity measure, how Big O notation describes them, and the common complexity classes from O(1) to O(n!) with code examples. ### Frontend System Design - [How the Web Works - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/how-the-web-works): At a high level, when you type google.com or flipkart.com, you make a request from the client to a server, and the server sends back a response. A server is… - [Communication Protocols - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/communication-protocols): Communication protocols are rules and standards that allow devices and applications to communicate over a network. They define how data is formatted… - [REST APIs - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/rest-apis): A REST API (Representational State Transfer Application Programming Interface) is an architectural style for networked applications that utilizes standard web… - [GraphQL - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/graphql): GraphQL is a query language for APIs and a runtime for executing those queries, where the client can request exactly the data it needs from a single endpoint… - [gRPC - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/grpc): gRPC (Google Remote Procedure Call) is a framework that lets a client call functions on a remote server as if they were local functions. - [Communication Overview - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/communication-overview): How does the frontend find out that something changed on the backend? There are five common techniques: Short Polling, Long Polling, WebSocket, SSE… - [Short Polling - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/short-polling): Short polling is a way for a client, like a browser or app, to repeatedly ask the server: "Do you have any new data for me?" It does this after a fixed time… - [Long Polling - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/long-polling): Long polling is a technique where the client asks the server: "Do you have any new data for me?" But instead of replying immediately, the server waits until… - [WebSockets - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/websockets): WebSockets provide a persistent, full-duplex (two-way) communication channel between client and server. Once the connection is established, both sides can… - [Server-Sent Events (SSE) - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/server-sent-events): Server-Sent Events (SSE) is a unidirectional communication protocol where the server pushes real-time updates to the client over a single long-lived HTTP… - [Webhooks - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/webhooks): Webhooks are a way for one system to send real-time data to another system via HTTP callbacks when an event occurs. Instead of polling (the client repeatedly… - [Performance Overview - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/performance-overview): Performance is about how quickly the browser and the server work together to get a usable page in front of the user, and how smoothly it responds afterwards… - [Performance Monitoring - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/performance-monitoring): Core Web Vitals are Google's key metrics for real user experience. They cover three things: loading (LCP), interactivity (originally FID, now INP) and visual… - [Accessibility Overview - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/accessibility-overview): Accessibility Overview for frontend system design interviews (Accessibility). - [Keyboard Accessibility - Frontend System Design Interview Guide](https://nagarajunali.com/interview-prep/frontend-system-design/keyboard-accessibility): Web accessibility means people with disabilities can perceive, understand, navigate, interact with and contribute to the web. Its goal is to remove the… ### Node.js - [Introduction to Node.js - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/introduction-to-nodejs): Node.js is a JavaScript runtime that lets you run JavaScript outside the browser, which is what makes it possible to write backend servers, command-line… - [Modules & CommonJS - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/modules-and-commonjs): CommonJS is the module system Node.js has used from the start: every file is its own module, and require/module.exports control what gets shared between them… - [npm, package.json & Semantic Versioning - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/npm-and-semver): npm is the default package manager for Node.js, and package.json is the manifest that describes your project, its dependencies, and how to run it. Reading… - [Core Modules & Global Objects - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/core-modules-and-globals): Node.js ships with a set of built-in modules for common tasks - files, paths, the OS, cryptography - so you rarely need a third-party package for basics… - [The process Object & Environment Config - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/process-and-environment): The process global is your window into the running Node.js program itself - its environment variables, command-line arguments, and lifecycle. Using it well is… - [The Event Loop - Free Node.js Tutorial](https://nagarajunali.com/interview-prep/node/the-event-loop): The event loop is the mechanism that lets single-threaded Node.js handle many concurrent operations without blocking. Knowing its phases, and how microtasks… ### Python - [Python Basics - Free Python Tutorial](https://nagarajunali.com/interview-prep/python/python-basics): Python is a high-level, interpreted, object-oriented language prized for readable syntax and a huge standard library, which is why it shows up everywhere from… - [Data Types - Free Python Tutorial](https://nagarajunali.com/interview-prep/python/data-types): Python's built-in data types cover numbers, text, and several kinds of collections, each with its own tradeoffs around mutability, ordering, and uniqueness… - [Operators - Free Python Tutorial](https://nagarajunali.com/interview-prep/python/operators): Operators are the building blocks of every Python expression - arithmetic, comparison, and logical operators combine values and conditions, and knowing their… - [Control Flow - Free Python Tutorial](https://nagarajunali.com/interview-prep/python/control-flow): Control flow statements decide which code runs and how many times - conditionals branch based on a test, loops repeat work, and break/continue give you… - [Functions - Free Python Tutorial](https://nagarajunali.com/interview-prep/python/functions): Functions package up reusable logic behind a name, so it can be called wherever needed instead of duplicated. Understanding parameters vs. arguments, return… ### Express - [Introduction to Express - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/introduction-to-express): Express is a minimal, unopinionated web framework built directly on top of Node’s http module. It takes the raw request/response handling Node already gives… - [Routing - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/routing): Routing is how an Express app decides which function should handle a given combination of HTTP method and URL path. Getting comfortable with… - [Route Parameters & Query Strings - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/route-parameters-and-query-strings): Most real routes need more than a fixed path - they need to accept an identifier, a filter, or an optional setting from the URL itself. Express gives you two… - [Middleware - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/middleware): Middleware is the concept that everything else in Express is built on: functions that sit in the request-handling pipeline, able to inspect or modify the… - [Express Router & Modular Routes - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/express-router-and-modular-routes): As an app grows past a handful of routes, keeping everything in one file becomes unwieldy. express.Router() lets you define a self-contained set of routes in… - [The Request & Response Objects - Free Express Tutorial](https://nagarajunali.com/interview-prep/express/request-and-response): Every route handler and middleware function works with the same two objects: req, representing the incoming HTTP request, and res, representing the outgoing… ### TypeScript - [Introduction to TypeScript - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/introduction-to-typescript): TypeScript is a typed superset of JavaScript that compiles down to plain JavaScript, adding a static type system on top of a language that otherwise stays… - [Basic Types - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/basic-types): TypeScript's basic types cover the same primitives JavaScript already has - strings, numbers, booleans - plus a handful of TypeScript-specific types like… - [Interfaces & Type Aliases - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/interfaces-and-type-aliases): Interfaces and type aliases are TypeScript's two main tools for giving a name to a shape of data, so that functions and variables can reference "a User" or… - [Functions & Type Annotations - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/functions-and-type-annotations): Typing a function means describing both what it accepts and what it returns, which lets the compiler catch a wrong argument or a misused result at every call… - [Classes & OOP in TypeScript - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/classes-and-oop): TypeScript extends JavaScript's classes with typed fields, access modifiers, and abstract classes, giving you the vocabulary of traditional object-oriented… - [Enums - Free TypeScript Tutorial](https://nagarajunali.com/interview-prep/typescript/enums): An enum gives a readable name to a fixed set of related constant values, such as the days of the week or the possible states of an order, instead of… ### MongoDB - [Introduction to MongoDB - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/introduction-to-mongodb): MongoDB is a document-oriented NoSQL database that stores data as flexible, JSON-like documents instead of rows in fixed tables. It is the default choice for… - [Documents & Collections - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/documents-and-collections): Documents are the basic unit of data in MongoDB, and collections are the containers that hold them. Understanding how the _id field works and how flexible… - [CRUD Operations - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/crud-operations): Create, Read, Update, and Delete are the four operations every application performs constantly, and MongoDB gives each one a small, consistent family of… - [Query Operators - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/query-operators): MongoDB query filters go far beyond simple equality matches. Comparison, logical, element, and array operators let you express rich conditions directly inside… - [Schema Design & Data Modeling - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/schema-design-and-data-modeling): MongoDB's flexibility means schema design is a deliberate application-level decision rather than something the database forces on you. Designing around how… - [Relationships: Embedding vs. Referencing - Free MongoDB Tutorial](https://nagarajunali.com/interview-prep/mongodb/relationships-embedding-vs-referencing): MongoDB gives you two fundamentally different ways to model a relationship between two pieces of data: embedding one document inside another, or storing a… ## Blog - [How AI Is Changing Software Engineering Jobs and Interviews](https://nagarajunali.com/blogs/ai-and-software-engineering-interviews): What companies now expect you to know about LLMs and AI tools, the AI questions showing up in interviews, and how to prepare. - [How to Build a MERN Stack App: From Tech Stack to Deployment](https://nagarajunali.com/blogs/how-to-build-a-mern-stack-app): How MongoDB, Express, React and Node.js connect in one app, and the 8 steps from planning the API to a live URL, with code for each layer. - [How to Build a MEAN Stack App: From Tech Stack to Deployment](https://nagarajunali.com/blogs/how-to-build-a-mean-stack-app): How MongoDB, Express, Angular and Node.js connect in one app, and the 8 steps from planning the API to a live URL, with code for each layer. - [Why Your Resume Gets Rejected Before a Human Reads It (and How to Fix It)](https://nagarajunali.com/blogs/why-your-resume-gets-rejected-by-ats): How Applicant Tracking Systems really filter resumes, the 8 mistakes that keep software engineers off the shortlist, and a 10-minute checklist to fix yours. - [The Frontend Developer Roadmap: What to Learn, in What Order](https://nagarajunali.com/blogs/frontend-developer-roadmap): A stage-by-stage path from HTML to system design, what "job-ready" means at each stage, and what you can safely skip. - [Crack DSA Rounds by Learning Patterns, Not 500 LeetCode Problems](https://nagarajunali.com/blogs/dsa-patterns-not-500-problems): The handful of patterns (two pointers, sliding window, recursion, hashing) behind most interview questions, with a 6-week practice plan. ## Optional - [About Nagaraju Nali](https://nagarajunali.com/about): Nagaraju Nali is a frontend engineer building fast, accessible web experiences with React, Angular, Node.js and MongoDB. 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