Guides for developers

A free online book that explains SQL indexing for developers, from how a B-tree is laid out to why a particular WHERE clause can or cannot use an index. It covers Oracle, MySQL, PostgreSQL, SQL Server and Db2 with product-specific notes. It is the clearest resource for turning index theory into faster queries.

• Web
• Databases
• Backend

A free online guide by Evan Smith on building kinder engineering teams, based on the difference between being nice (polite and agreeable) and being kind (actively investing in others). It gives concrete practices for honesty, asynchronous communication and code review, psychological safety, and giving feedback. It suits engineers, tech leads and new managers who want better team habits, and anyone whose code reviews feel harsh.

• Career
• Programming
• Leadership

GitHub's official guide to the profile README: a public repository named exactly after your username, containing a README.md, whose contents appear at the top of your GitHub profile. It explains setup, requirements and how to remove it. Use it to point recruiters and reviewers straight at your best projects instead of making them dig through every repository.

• Career
• Personal branding
• Dev tools

Patterns.dev is a free site and book by Lydia Hallie and Addy Osmani that explains design, rendering and performance patterns for modern web apps, with examples in vanilla JavaScript, React and Vue. It covers classic patterns such as Observer and Factory, plus server rendering, streaming, React Server Components, bundle splitting and prefetching. It suits developers who can build features but want to understand why an app is structured and loads the way it does.

• Web
• Frontend
• Programming

A free newsletter of short, focused posts on system design and problem solving, from the team behind the Grokking courses. Recent posts cover company interview processes (such as OpenAI and Anthropic roles), the most asked mobile system design questions and preparation plans, each linking to a fuller article on the blog. It suits engineers who want a steady, low-effort way to keep system design and interview topics fresh between deeper study sessions.

• System design
• DSA

The official Node.js Learn guides explain what Node itself is doing underneath your framework: the event loop, asynchronous work, files and streams, HTTP, environment variables, running TypeScript, diagnostics and the built-in test runner. The articles are short and free. They suit JavaScript developers who use Express, Next.js or another tool but want to understand the runtime, and anyone debugging a problem that a framework tutorial glosses over.

• Web
• Backend
• Programming

The official FastAPI tutorial and user guide builds an API one concept at a time: path and query parameters, request bodies with Pydantic validation, response models, error handling, dependency injection, OAuth2 with hashed passwords and JWT, SQL databases, bigger applications, background tasks and testing. One of the few framework docs that doubles as a genuinely good backend course, for Python developers building modern APIs.

• Web
• Backend
• Programming

The TypeScript Handbook is the official, free guide to TypeScript's type system from the TypeScript team, written for working programmers and kept current with each release. It covers everyday types, narrowing, functions, object types, generics, type manipulation, classes and modules, and it is designed to be read in a few hours. It suits JavaScript developers adopting TypeScript and anyone who writes types by copying patterns without understanding them.

• Web
• Programming

The official documentation for Tailwind CSS v4, the utility-first CSS framework. It covers installation (a Vite plugin, PostCSS, the CLI and framework guides), core concepts such as states, responsive design, dark mode and theme variables, and a page for every utility showing exactly the CSS each class produces. It suits frontend developers using Tailwind, who should keep it open while building, and anyone moving a project from Tailwind v3 to v4.

• Web
• Frontend

A free website by Will Larson with guides and interviews about the staff engineer role and the senior individual contributor track: the four common archetypes, how people got promoted, and what the work involves day to day. It accompanies his 2021 book Staff Engineer: Leadership beyond the management track. The clearest free answer to what comes after senior if you do not want to manage.

• Career
• Leadership

A newsletter by Gergely Orosz on software engineering as a profession: how tech companies run teams, set pay, promote and hire, and what is changing in the industry right now. It is built on reporting from people inside companies rather than opinion. Useful for engineers deciding where to work, when to move, or how their own company compares.

• Career
• Leadership
• Job search

MDN Web Docs is Mozilla's open, community-maintained reference for HTML, CSS, JavaScript, HTTP and browser APIs, with browser compatibility tables on every page and a structured Learn area for beginners. It is free, and a paid MDN Plus tier adds extras such as AI help and collections. It suits every web developer, from someone writing their first page to a senior engineer checking exactly how an API behaves across browsers.

• Web
• Frontend
• Programming

The Modern JavaScript Tutorial by Ilya Kantor is a free online course that teaches JavaScript from the basics through objects, prototypes, closures, classes, promises, async/await and modules, then covers the browser's document model and events. Most chapters end with tasks and solutions. It suits beginners who want a thorough written path and developers whose JavaScript came from framework tutorials and who keep hitting confusing bugs.

• Web
• Programming
• Frontend

The official React documentation at react.dev is a full course as well as a reference. Its Learn track moves from a quick start through describing the UI, adding interactivity, managing state and escape hatches, with interactive sandboxes and challenges on nearly every page. It suits anyone learning React and any React developer whose habits come from older class-based tutorials, and it should be read before paying for a React course.

• Web
• Frontend
• Programming

web.dev is written by members of Google's Chrome team and outside experts, and covers web performance, accessibility and modern browser features. It hosts free structured courses such as Learn HTML, Learn CSS, Learn JavaScript, Learn Performance and Learn Accessibility. It suits front end developers who need to understand Core Web Vitals, make pages faster and more accessible, or check whether a new platform feature is safe to use.

• Web
• Frontend
• Programming

Anthropic's official, free guide to prompting Claude, written by the team that trains the model and updated as new models ship. It covers clarity, context, examples, XML structure, roles, long documents, output format, thinking, tool use and agentic systems. It suits developers building on any large language model who want techniques that work on current models rather than tricks from two generations ago.

• AI

The official documentation for the Model Context Protocol (MCP), an open standard for connecting AI applications such as Claude, ChatGPT, VS Code and Cursor to external tools and data. It includes the specification, concept guides, tutorials for building servers and clients, and official SDKs in several languages. It is for developers who want to give a model access to their systems through a standard interface.

• AI
• Backend

OpenAI's open source collection of runnable examples and guides for recurring tasks in AI application work: agents, retrieval and embeddings, structured output, function calling, evaluation, voice and realtime, vision and image generation, and cost management. It is a set of recipes to read and adapt rather than a course or architecture essays, and most techniques carry over to other providers.

• AI
• Programming

A free, diagram-led article by Jay Alammar that explains the transformer architecture step by step: self-attention, multi-head attention, positional encoding, the encoder and decoder stacks, and how the model is trained. It is the standard first read for anyone who has heard that attention is all you need and still does not know what attention does, and takes around an hour.

• AI
• Machine learning

An Anthropic article from December 2024 that separates workflows (models run through fixed code paths) from agents (models directing their own steps) and describes the common patterns for each. It is for engineers designing any system with more than one model call. Its main lesson is to start with the simplest pattern that works and add autonomy only when the problem needs it.

• AI
• System design

A free, browsable collection of system design lessons that opens with a roadmap for learning system design by career level. It covers the fundamentals (distributed system characteristics, networking, DNS, load balancing, API design, caching, partitioning, CAP, databases, indexes), trade-offs, how to approach a design interview, and walkthroughs of classic problems. It works as a reference while you practise and as a sample of the teaching style before choosing a course.

• System design
• Backend

The well-known Blind 75 interview problem list, grouped into five topic areas with a difficulty level, a practice link and a step-by-step solution for each problem. Free to use, with hints, an in-browser coding workspace, notes and progress tracking. A focused way to cover the most frequently asked problem types and to check whether your preparation is working.

• Job search
• DSA

Free interview handbooks for software engineers applying to Amazon, Microsoft, Meta, Google and Oracle. Each guide describes the company's hiring process, the rounds you will face, commonly asked questions, and tips and resources for preparing. Read the guide for your target company once your interview is scheduled, so you can adjust your final weeks of preparation to what that company emphasises.

• Job search
• Career

The official documentation for Elasticsearch, the search and analytics engine behind many product search bars, log tools and site search. Learn how documents become an inverted index, how full-text queries are scored, and how to run it locally or on Elastic Cloud.

• Web
• Databases
• Backend