Algorithms and Data Structure are two of the most fundamental and essential topics in Computer Science, which is used everywhere in software development. I firmly believe that a good knowledge of these two topics is also crucial to becoming a better programmer because a person who has a good understanding of algorithms and data structures can make thoughtful choices and write programs that can handle changes better and perform well. They are also essential to crack coding interviews at top tech companies like Google, Microsoft, Amazon, Facebook, and Apple, which emphasizes candidates' ability to use existing data structures and algorithms to solve complex problems they have never seen before. The only way to succeed in those interviews is a strong knowledge of all fundamental algorithms, data structures, and programming techniques like Recursion, Bit Manipulation, etc. Another thing that I have noticed in programmers is shallow/partial knowledge of data structures. Many programmers think that just knowing the array or linked list is enough, but that's true because everybody knows that. To distinguish yourself from the crowd, you also need to explore advanced data structures like a binary tree, binary search tree, balanced tree, heaps, graphs, hash tables, doubly linked list, circular list, stack, queue, and a tree with more than two nodes, etc. If you are determined to take your data structure and algorithm skill to the next level and look for some excellent free resources, you have come to the right place. In the past, I have shared the best online courses, books, tutorials, and interview questions on algorithms and data structure, and today, I'll share some of the best courses on data structure and algorithms, which are also free. These are online courses, so you can use them to learn data structure and algorithms in the comfort of your office or home. You can also go at your pace and spend time on topics you find hard to understand. These courses cover both basic data structures like an array, linked list, and binary tree and advanced data structures like a stack, queue, trie, balanced tree, graphs, etc. By the way, if you don't mind spending few bucks to learn an important programming skills like Data STructure and algorithms then also suggest you to join Master the Coding Interview: Data Structures + Algorithms course by Andrei Negaoie on Udemy. It's one of the most comprehensive course to learn DSA as well prepare for coding interviews in 2025. Andrei is a great instructor and you will thank me later for recommending this course. 12 Best Free Data Structure and Algorithms Courses for Beginners on Udemy in 2025 Without any further ado, here is my list of some freely available courses to learn data structure and algorithms. I have purposefully included courses that teach this topic in different programming languages like C, C++, Java, JavaScript, Python, etc. Even though the data structures and algorithms are generic, you can understand the implementation better if given in the programming language you know better. 1. Data Structure - Part I [FREE] This 5-hour long free Udemy course is one of the best courses you can get for free to learn data structure and algorithms. The course contains over 5 hours of content and, as the name suggests, covers essential data structures like an array, linked list, and stack in Java programing language. You will learn about the array, linked list, dynamic array, stack, and how to calculate runtime time complexity for your algorithms and solutions. The course will also show you live examples of code analysis so that you can do it on your own. In short, a complete guide to learning about data structures and algorithms. A big thanks to instructor for keeping this excellent course free. If you are a beginner and want to learn essential data structure in the Java Programming language, this free course is for you. More than 40,000 people have already joined this course. 2. Algorithms Part 1 [Free Coursera Course] This is another fine free online course on algorithms from Coursera. This course takes you on a guided tour of the field of data structures, algorithms, and complexity analysis. The concepts are language-independent, and solutions and Big O calculations are done in Java. It's a two-part course, in which the first part covers basic data structures, sorting algorithms, and searching algorithms, while the second part focuses on the graph and string-processing algorithms. The course is offered free from Princeton University, and both instructors, Kevin Wayne and Robert Sedgewick are expert authors and lecturers. Robert Sedgewick has also authored the Algorithms book, one of the best books to learn Data Structure and Algorithms in Java. Talking about social proof, the course has got 4.9 reviews from 1000 reviewers, which is impressive. Once you enroll, you will have access to all course material, and it's completely free, but no certificate of completion will be given, unlike other Coursera courses. More than 1,227,445 people have already enrolled in this program which makes it probably the most popular online course on Algorithms By the way, if you find Coursera courses useful, which they are because they are created by reputed companies and universities around the world, I suggest you join Coursera Plus, a subscription plan from Coursera which gives you unlimited access to their most popular courses, specialization, professional certificate, and guided projects. 3. A Visual Introduction to Algorithms [Free Course from Educative] Many programmers and online courses shy away from teaching Algorithms because it's complex and difficult to learn and implement, but that's where it becomes important. Many real-world problems can be solved using graphs like the shortest path between cities and routes airline takes. Thankfully, you have a free course that provides a complete overview of essential computer science and mathematics algorithms. In this course, you will learn about common computer science algorithms like searching, sorting, binary search, and graph traversal algorithms like breadth-first traversal. The best thing about this free interactive algorithms course is that you will learn essential Computer science algorithms, including searching, sorting, recursion, and graph theory, through articles, visualizations, quizzes, and coding challenges. Implement Challenges in Java, Python, C++, or Javascript. You will also learn how to implement and store graphs on a computer. In short, a perfect course to learn about Graph data structure and algorithms. Educative is an excellent platform for learning new skills and preparing for coding interviews. Their Grokking courses like Grokking the System Design Interview and Grokking the Coding Interview Patterns are awesome. If you are preparing for coding interviews, I suggest you take an Educative subscription which costs around $14.9, and provide access to all of their 100+ interactive courses. 4. "Learn Data Structures" on Boot.dev This is one of the interactive free course to learn essential data structure in Python and suitable for both beginners and newcomes. There is also a course called Learn Algorithms, and together you can use them to learn both Data Structure and Algorithms. These DSA courses, written in Python, will help you master all the skills you need to crack coding interviews and land development jobs. The best part? This isn't just theory, Boot.dev teaches hands-on coding skills every step of the way. You'll be applying DSA principles to real world coding projects and challenges in every lesson. The best part? Boot.dev is super fun. They have a gamified fantasy feel to the platform that makes the whole learning experience addicting and engaging. The lessons are free, but you can also use code JAVINPAUL to get 25% off of a membership that will get you certificates of completion, progress verification, and more! 5. Google coding interviews on Data structure and Algorithms [Free]Competitive programming is a great way to develop Data Structure and algorithm skills. By preparing for FAANG interviews, you can learn things like Dynamic Programming, an important technique to solve complex coding problems in interviews. If you are preparing for job interviews, besides knowing data structures and algorithms, you should also learn about techniques like recursion, iteration, and dynamic programming. The course discusses many programming problems that can be solved using dynamic programming techniques like Longest Increasing Subsequence, Sum of the Range, Share market analysis, etc. After solving those questions and understanding their analysis, you will help to develop a strong intuition for any kind of Dynamic programming problem when approaching solving new problems. In this course, you will not only learn Dynamic Programming but several other useful algorithms. 6. Data structure and algorithms using C, C++, Java, Python [Free Udemy Course]This is a beginner's course to learn basic data structures' design, implementation, and analysis using Java, C, C++, and Python Programming language. In this free Udemy course, you will learn essential data structures and algorithms like array, linked list, binary tree, Stack, Queue, Trees, Graphs, Searching and Sorting from scratch. In this course, you can learn all sorting algorithms like selection sort, insertion sort, merge sort, bubble sort, and quick sort. It also covers advanced data structure concepts like backtracking, dynamic programming, Recursion etc. The course stands out by offering programming examples in a diverse range of languages such as C, C++, Java, Python, JavaScript, Ruby, and more. It is an ideal choice for those new to data structures, as each topic is meticulously explained from the ground up, accompanied by real-world examples and programming code. The course aims to guide learners through a comprehensive journey, enabling them to master DSA concepts by the end of the program. The inclusion of multiple-choice questions (MCQ) and problem-solving sessions enhances the learning experience, making it a perfect resource for individuals seeking a solid foundation in data structures and algorithms. Talking about social proof, this is a relatively new course but it has already got 500 students and 4.7 ratings from raters. Given this is just a 1 hour 52 minute long course, you can finish it quickly and learn basic data structure and algorithms for free. You can further check this course description to learn more about it. 7. Data Structures Concepts & Singly Linked List Implementation This short course teaches basic data structures like an array, linked list, stack, queue, and deque in the C programming language. You will learn to implement various linked list operations using the C programming language, like finding a node, appending a node, deleting a node, adding a node to a position, traversing a linked list, and preparing a node. You will also learn to solve some typical linked list-based coding problems like adding a node at the end of the linked list, adding a node at the beginning of the linked list, deletion a node from the beginning, and deleting a node from the end. 8. Introduction to Algorithms and Data structures in C++ [FREE] This is a great course to learn fundamental data structures and algorithms in C++. The instructor, Andrei Margeloiu, has a lot of experience in solving algorithmic problems and participate and win several coding competitions even organized by Google and Facebook. In this course, you will not only learn about fundamental data structures like an array and linked list, stack, and queue, but you will also learn about practical techniques to solve algorithmic problems. The instructor also shows you how to debug and analyze algorithmic complexity and Big(O) numbers. He also uses a lot of diagrams to convey his thoughts better and teach you visually, which is very important for a data structure and algorithm course. In short, an excellent free course to learn from an expert who himself has solved 1000+ algorithmic problems. Even though I know the topic, I have learned a couple of helpful tricks from this course; a big thanks to Andrei for keeping this course free. 9. Data Structures in Java for Beginners [Free Udemy Course] This course is very similar to the previous course except that it teaches you in Java language, and it completely focuses on a linked list, like both singly and doubly-linked lists. You will learn about all the linked list operations and how to implement them using Java Programming language, like adding a node and deleting a node from both beginning and end. Overall, a short course to focus on a linked list data structure. 10. Data Structures & Algorithms in Python - Coding Interview This is another free course to learn data structure and algorithms in Python programming language if you are preparing for an interview and don't have much time. The course is neither very long nor very short and contains just 1.5 hours' worth of content. In this free Python data structure you will not only learn the basics of an array, linked list, binary tree, binary search tree, stack, queue, AVL tree, and splay trees but also solve some coding problems and learn some tricks to do well on coding interviews. Created by Akash Sachdeva, the course is absolutely free when writing, but it can turn into a paid course anytime; hence I suggest you join early before the instructor converts it to a paid course. More than 8000 students have already joined this free course. 11. Data Structures And Algorithms In Real World - Part 1A lot of people ask me about where exactly data structure and algorithm is used in real world? Since there are not many courses and books who explain DSA with a practical approach but this free DSA tutoria is different. Data Structures And Algorithms In Real World - Part 1" is another great free course and tutorial for programmers. This course is designed to provide a practical understanding of Merkle tree by guiding learners through the process of building a miniature Git version in JavaScript. Created by Anto Aravinth, the course has garnered a commendable rating of 4.5 out of 5 from 35 students, attesting to its effectiveness. With 3,655 students enrolled, this on-demand video series spans 1 hour and 20 minutes, making it a concise yet comprehensive resource. The course is presented in English and includes subtitles in English [Auto]. Currently available for free, it caters to a diverse audience, including students, experienced professionals, and individuals preparing for interviews. I highly recommend you to join this tutorial to delve into the real-world applications of Merkle tree and enhance your understanding of data structures and algorithms in a practical context, and its completely free. 12. Algorithms and Data Structures - Part 1 [Pluralsight Free Trial] This is a comprehensive two-part course to learn algorithms and data structure. The course is focused on core data structures and algorithms used in everyday applications. You will learn the trade-offs involved in choosing each data structure, traversal, retrieval, and update algorithms. The first part of this series covers basic data structures like linked lists, stacks, queues, binary trees, and hash tables, and the second part focuses on advanced data structures and algorithms like data sorting, string searching, sets, and AVL trees, and concurrency issues. The last two algorithms and data structure courses from Pluralsight are not exactly free as you need a Pluralsight membership to access them. If you are not a member, then a Pluralsight monthly membership costs you around $29 per month and an annual membership around $299, providing access to more than 5000+ latest technology courses. I have Pluralsight membership, and it's my go-to place to learn new stuff, but if you just want to access these courses, you can also try Pluralsight's free trial, which provides 10-day access to all Pluralsight contents. That's all about some of the best free Algorithms and Data Structures courses on Udemy in 2025. Good knowledge of data structures and algorithms goes a long way in making you a good programmer. They help you write better code and help you do well in coding interviews, where you will always find some questions on algorithms and data structure. If you feel you need to improve your understanding of the algorithms, these courses are great to start, and you won't need to worry about money because they are free. Also, even though most of these courses are free, you will have lifetime access to the course material; just be careful with Udemy free courses. Most of them are made free for promotional purposes, and sometimes, when they achieve their target in terms of ratings and reviews to collect social proof, their instructor converts them to a paid course. It's always better to check the price, of course, before you click the enroll button. Other Programming Resources you may like 50+ Data Structure and Algorithms Interview Questions 10 courses for Programming/Coding Job Interviews 75+ Coding Interview Questions for Programmers 30+ Array-Based Questions from Interviews 30+ LinkedList Based Java Interview Questions Grokking Algorithms - Book Review 21 String Programming Questions from Interviews 10 Data Structures and Algorithms Courses for Interviews How to solve scenario-based Algorithms Interview Questions Top 5 Data Structure and Algorithms Books for Programmers 20 Binary Tree Based Interview Questions 5 Best Courses to learn Data Structure and Algorithms in JavaScript My Favorite Python Data Structure and Algorithm Courses Thanks for reading this article so far. If you like these best free Algorithms and Data structure courses, please share them with your friends and colleagues. If you have any questions or feedback, then please drop a note. P. S. - If you don't mind paying $10 for an excellent course and value your time more than money, I suggest you check out this list of best Data Structure and Algorithms courses. P. S.S - If you prefer books over courses, you should check my list of 10 Algorithm books every programmer should read.