Complete Intro to React, v9 vs The Last Algorithms Course You'll Need

The course covers React 19 from initial project scaffolding with Vite through hooks (useState, useEffect, useContext, useReducer), component composition, routing with TanStack Router, and performance patterns — all organized around building a production- style e-commerce application rather than isolated toy examples. Reviewers consistently praise the modern toolchain (no Create React App), the focus on current patterns that actually work in production codebases, and the absence of outdated class-component material. The v9 designation signals genuine curriculum updates rather than cosmetic refreshes, which is rare among multi-version React courses.

Brian Holt is described across all reviewed sources as an exceptional teacher — specifically praised for making complex concepts feel obvious through clear analogies, methodical build-up, and a conversational delivery that stays engaging across eight hours of video. Multiple reviewers note that experienced React developers still learn meaningful things from Holt's explanations, suggesting depth beyond what the beginner framing implies. He is repeatedly described as a GEM among Frontend Masters instructors.

The course requires a Frontend Masters subscription ($39/month or $390/year), which gives access to the full course catalogue of 200+ expert-level courses — not a single-course purchase. For developers who intend to use more than a few courses, the subscription offers strong value. For learners who only want this one course, the subscription model is a higher upfront cost than a typical Udemy purchase. Frontend Masters does not offer a permanent free tier, though the course notes and exercises are publicly accessible at react-v9.holt.courses.

The e-commerce project format means learners build a real application rather than disconnected code snippets, and the toolchain — Vite, ESLint, Prettier, TanStack — mirrors what professional React teams actually use. Reviewers who moved directly from the course to their first React role or freelance project report that the patterns transferred immediately. The course avoids outdated approaches that would confuse learners encountering a modern codebase, which sets it apart from older React curricula still teaching class components as the primary pattern.

Building a complete e-commerce application — covering product listings, a shopping cart, routing, and state management — gives learners a deployable project and a portfolio piece, not just completed exercises. Reviewers highlight that the project scope is substantial enough to demonstrate real React understanding without being overwhelming. The course's companion notes at react-v9.holt.courses also let learners self-pace the text-based curriculum independently of the video playback speed.

Across roughly nine hours and 60 lessons the course covers Big O time and space complexity, arrays, linked lists, queues and stacks, a ring buffer, recursion, the classic searches and sorts (linear, binary, bubble, quick), trees with BFS and DFS, heaps, maps, graphs with adjacency lists and matrices, and Dijkstra's shortest path. Reviewers repeatedly call it content-dense and "not the typical watered down content you find often on online courses." The honest mark-down is that it is implementation-first and fast — it condenses a full-semester CS course into under ten hours, so it favours breadth and live coding over slow, proof-heavy depth.

ThePrimeagen is the reason this course is so widely recommended. Reviewers describe his explanations as "full of joy and charisma," call him "an excellent communicator" who is "both down-to-earth and incredibly skilled and intelligent," and note that "you won't get bored and fall asleep." He implements most algorithms live rather than showing finished code, which learners consistently single out as the high point. This is one of the most engaging instructors in the DSA space and it shows in the 4.9/5 rating.

The course is completely free — all you need is a free Frontend Masters account — yet it sits behind, and is the same quality as, Frontend Masters' paid catalogue. For roughly nine hours of well-produced video plus a bespoke practice tool, reviewers call it "a worthy investment" and say "there is no other algorithm course that can teach you so many topics in such an efficient way." The only caveat on value is the subscription framing: the deeper Part 2 (advanced algorithms) sits behind a paid Frontend Masters subscription.

The standout practical feature is the kata-machine, a bespoke GitHub repository ThePrimeagen wrote that generates a fresh daily set of algorithm exercises with a ready testing environment, so you implement each structure from scratch in TypeScript rather than just watching. Learners praise this as the thing that makes the knowledge stick. The caveat is that there is no graded capstone or certificate, and some implementations (notably the doubly linked list) are "complicated, or rather convoluted, to implement," which can stall practice.

The stated goal is to teach enough DSA that, after practice, you could pass interviews at a large tech company, and reviewers report it delivered exactly that mental model — one four-year professional said "this was exactly what I needed to get back on track." The patterns (Big O reasoning, BFS/DFS, Dijkstra, the common sorts) are the bread and butter of coding interviews. But it is a foundation, not a credential: there is no certificate, and complete beginners will need significant outside practice before the interview goal is realistic.