Coding interview preparation has become an industry. LeetCode Premium runs $35 per month. AlgoExpert charges $99 for lifetime access. Interview prep bootcamps cost thousands. The market has identified anxious engineers and priced accordingly.
The secret most experienced engineers know is that you do not need any of it. The free resources — particularly on YouTube — are sufficient to prepare for interviews at any company. What you need is not a premium subscription but a structured approach, the right study materials, and the discipline to practice consistently.
This guide gives you a complete free coding interview prep strategy using YouTube as the primary resource.
Understanding What Coding Interviews Actually Test
Before talking about preparation, it is worth being clear about what coding interviews test, because a lot of preparation effort goes toward the wrong things.
FAANG-style coding interviews test your ability to solve algorithmic problems under time pressure with clean, correct code. The problems are deliberately drawn from a well-defined pool — dynamic programming, graph traversal, tree problems, two-pointer techniques, sliding windows, binary search variations. There are roughly 15–20 distinct problem patterns, and mastering those patterns prepares you for the vast majority of problems you will encounter.
They do not primarily test how many problems you have solved. Someone who has deeply understood 100 problems and can articulate their reasoning clearly outperforms someone who has memorized 500 solutions. The goal is pattern recognition and implementation fluency, not volume.
This matters because it changes how you should study. Grinding through hundreds of LeetCode problems randomly is less effective than studying the core patterns systematically, then practicing problems within each pattern.
The YouTube Study Plan
Phase 1: Build the Foundation (4–6 Weeks)
Start with a complete data structures and algorithms course before touching any LeetCode problem. This is the step most people skip, and it is why they plateau.
Abdul Bari's algorithms playlist is the strongest complete DSA course on YouTube. He covers time and space complexity analysis, every major sorting algorithm, trees, graphs, hash tables, heaps, and dynamic programming in a logical sequence: https://courseifier.com/course/PLWJMZ4TNhvXEWD0YoONdLuHJijbQxmWtG
After Abdul Bari's conceptual foundation, MIT 6.006 provides the theoretical rigor that makes you able to analyze new problems rather than just recognize familiar ones: https://courseifier.com/course/PLUl4u3cNGP61Oq3tWYp6V_F-5jb5L2iHb
Open both playlists on Courseifier and take structured notes. Your notes from this phase become a reference you will consult throughout your preparation. Our post on active recall for video lectures covers how to study these courses in a way that maximizes retention rather than just coverage.
Phase 2: Pattern-Based Problem Study (6–8 Weeks)
After the foundation, move to problem-pattern study. NeetCode's YouTube channel is the best free resource for this phase. NeetCode has produced a curated list of 150 LeetCode problems organized by pattern — arrays, two pointers, sliding window, stack, binary search, linked lists, trees, graphs, dynamic programming — and provides video explanations for each.
The free NeetCode 150 list is publicly available without any subscription. You solve problems on LeetCode's free tier (which includes the vast majority of NeetCode 150), watch NeetCode's explanations when you are stuck, and build pattern fluency systematically.
The key discipline in this phase is attempting each problem before watching the solution. Set a timer for 25 minutes. If you cannot solve it in 25 minutes, spend five more minutes identifying what approach you would try and where you are stuck, then watch the explanation. This is far more effective than watching solutions first and feeling like you understood.
Phase 3: System Design (4–6 Weeks, Parallel With Phase 2)
For mid-level and senior engineering roles, system design interviews are as important as coding interviews. Our dedicated post on learning system design from YouTube maps out a complete free study path. The short version: start with Gaurav Sen's playlist, add ByteByteGo for visual reinforcement, and practice designing full systems in writing.
Phase 4: Mock Interviews and Behavioral (2–4 Weeks)
The final preparation layer is simulating interview conditions. ExponentHQ on YouTube has mock interview videos where you watch real engineers interview each other — useful for calibrating pacing and communication style. Clément Mihailescu's AlgoExpert YouTube channel includes free mock interview content.
For behavioral interviews, practice STAR format answers for the standard question categories: conflict resolution, leadership, failure and recovery, technical achievement. Write them out rather than winging it — the structure matters, and written practice produces better answers than mental rehearsal.
Using Courseifier for Interview Prep
The challenge with interview prep is keeping everything organized across a study campaign that lasts months. You are working from multiple YouTube playlists, maintaining a problem log, and tracking which topics need review.
Courseifier helps by turning each YouTube playlist into a structured course with persistent progress. Open Abdul Bari's series, MIT 6.006, and NeetCode as separate courses on https://courseifier.com. Keep per-lecture notes on the concepts you studied, the problems you solved, and the patterns you are still shaky on. Export your notes as a single Markdown file for review sessions.
The progress tracking is particularly useful during the grind of Phase 2. Month-long preparation campaigns are motivationally difficult, and seeing your completion percentage on each playlist move forward each week helps maintain momentum.
The Free Tier Is Enough
LeetCode's free tier includes the vast majority of the problems in NeetCode 150. The problems tagged as Premium tend to be company-specific rather than pattern-exemplars — useful if you are targeting a specific company but not necessary for general preparation.
The things LeetCode Premium gives you — streak tracking, company tags, additional problems — are conveniences, not necessities. The preparation quality difference between someone who used LeetCode free + NeetCode YouTube and someone who paid $35/month is minimal. The difference between someone who studied systematically and someone who ground randomly for the same hours is enormous.
Systematic, free, YouTube-based preparation is not the fallback for people who cannot afford premium resources. For most learners, it is the best approach.
Start with Abdul Bari's algorithms playlist today: https://courseifier.com/course/PLWJMZ4TNhvXEWD0YoONdLuHJijbQxmWtG