What Our Students Say

it was good just the practice lessons github was not accessible

This course is so good and prepared with fully understandable explanations for users of any experience level. But I think the context or cases should be more updated with recent issues. Overall, it's good.

Crazy! It's sooo much value on this course!

Excellent course . Johnny did a remarkable work for the content of the course.

It has been amazing!!!

It was challenging but I made it through! :) Thanks to JohnnyTime and Blockchain Sec Academy!

The course delivers a clear and practical introduction to smart contract security. I especially liked the hands-on approach and the way real-world vulnerabilities were explained in a simple, structured way. As someone coming from a non-technical background, I found the explanations accessible without being overly simplified. The examples helped me understand how attacks actually happen, not just the theory behind them. Overall, this is a solid and valuable introduction to Web3 security, and it definitely made me more interested in going deeper into the field.

This course helped gain insights on attack vectors along with hands-on exercises.

I've been a traditional penetration tester for two years and wanted to look into Smart Contract hacking as a hobby. This course has been fantastic! Concepts that I had heard of, but was fuzzy on, were explained clearly. The practical hands-on exercises are genuinely fun and I feel that they are really setting me up for a successful side-career in auditing!

It's a good course. Johnny explains things in a simple way and with very practical exercises. Recommended for those who want to venture into the world of smart contract security.

Good job!

Good !

Awesome.

Everything good

All good. I like it.

Great!

awesome course especially the reentrancy part

<3

I really enjoyed this course, and feel like I have a great foundation to start participating in Audit Competitions or Become a Smart Contract Tester

<3

Yeah its a good course learned some new ways to hack the smart contracts using re-entrancy and access control which I don't know before....

very nice! i began with Patrick and cyfrin courses, but this one is more hacking focused, more tailored to start competing in BB and audits

amazing

Amazing course, brilliant explaination and amazing repository to make practice!

Nice course and explained very well. You can gain a good knowledge and hands on practice

Very informative, a lot of fun!

Very well structrured course, the excersies are boom.

An excellent foundational course, it was an absolute pleasure to go through. Yes, there are some inconsistencies, and some syntax and links to materials are a bit outdated, but it's still the best beginner-friendly course available. Personally, I missed a dedicated module on audit reports and a nice way to convert md to pdf. The course is definitely worth the attention, and I hope new lessons will be added in the future. I also felt the lack of coverage of the ZKlend hack, since in one of the lessons we use a flash loan there, but the protocol has already been hacked and the project shut down. I really hope the authors will keep the course up to date. Thanks for your work guys - it was an absolute pleasure to take it!

Amazing clurse with wide range of vulneabilities and auditing methodology

Overall, a solid course. I just missed some live coding during the explanations - static screenshots felt unusual there. Also, using outdated versions of snfoundry, the compiler, and the language was a bit inconvenient. Some links in the assignments were also broken. That said, I'm satisfied with the course overall.

Learning a lot

It was a very good match for me. I love the course. The hands on experience I got from the course is top notch

It was really a good course, ready for the contests ! Thank you !

It was really nice to get to go deeper on this topic, and I noticed myself advancing a lot more. Now with my experience and with this under my toolbelt I'm more confident to move forward on this world. Thanks for this, it is needed in times when I got layed off and I need to reinvent myself!

Great course ! Thank you !

This course (Smart Contract Hacking – Part 1) is a must-take for anyone serious about smart contract security, whether you’re a complete beginner or an experienced auditor looking to fill gaps in your knowledge. JohnnyTime’s expert guidance, paired with rich hands-on labs and a vibrant community, makes this an outstanding learning experience. I wholeheartedly recommend it!

It provided clear and insightful explanations that helped me deeply understand common vulnerabilities in smart contracts. It was both practical and eye-opening, and I’ve learned a lot that I can apply in real-world blockchain development.

Absolutely incredible resource! Within the Web3 space the best there is. Hat off to JohnnyTime and all the guest lecturers for their amazing content and teachings!

Excellent analysis of different attack vectors in context of Cairo

The course was excellent. The exercises were hands on and practical. Look forward to be able to use what I've learnt in contest.

What an amazing first half of the course, simply amazing. I am learning so so much. Thank you very much Johnny, and maybe Part2 be just as great if not better!

Amazing, great coverage. Johnny goes in depth, also keeps the content to the point which is great!

Meeting expectations!

This course is an excellent choice for developers aiming to master Cairo programming and blockchain scalability. It covers fundamentals to advanced concepts, including STARK-based computations. The practical projects and emphasis on security make learning hands-on and impactful. The knowledgeable instructors ensure complex topics are easy to grasp. Highly recommended for anyone passionate about blockchain innovation!

⭐️⭐️⭐️⭐️⭐️ The Cairo Smart Contract Hacking Course is an absolute must for anyone serious about blockchain security, smart contract auditing, and Web3 development. This course goes beyond the basics, offering deep insights into vulnerabilities, attack vectors, and secure coding practices in Cairo, the programming language for StarkNet. 🚀 Why This Course Stands Out: ✅ Hands-on Approach – Real-world hacking scenarios and practical exercises. ✅ Expert-Led Content – Taught by industry professionals with deep expertise. ✅ Comprehensive Coverage – From basic vulnerabilities to advanced exploit techniques. ✅ Web3 Security Focus – Learn offensive & defensive strategies for secure smart contracts. ✅ Community & Support – A vibrant learning environment with like-minded security enthusiasts. Whether you're an auditor, developer, or security researcher, this course equips you with the knowledge and skills needed to protect and exploit Cairo-based contracts. Highly recommended for anyone diving into the future of blockchain security! 🔥💡 🚀 Final Verdict: 10/10 – A must-learn for Web3 security enthusiasts! 🛡️

The course explains the nitty gritty of cairo programming language, concepts and well detailed cairo smart contract implementation.

Great sneak peak of the course with practical exercises

It was amazing section of the course. The way he has explaind has cleared alot of basic stuff. Also it was smooth and easy to understand. Informative and mostly cleared each and everything during the course.

One of the best 😎

The "Smart Contract Hacking Course" exceeded my expectations in every way. It provided a well-rounded, in-depth understanding of smart contract security, making it highly beneficial for both beginners and seasoned professionals in blockchain development. The course covered a wide range of vulnerabilities and attack vectors, offering hands-on examples to reinforce the learning. The interactive format and real-world case studies made complex topics approachable and engaging. I especially appreciated how the instructors emphasized preventive measures and best practices for writing secure smart contracts. Overall, it was an incredibly insightful experience that has significantly enhanced my skills. I’d highly recommend this course to anyone looking to deepen their expertise in blockchain security or ensure the robustness of their smart contracts.

The first part of the course is amazing, I learned a lot of topics

I loved it . I started to build my hacker's mentality thanks to the exercises in that course and the great explanations and materials from Mr. Johnny, great guidance from his part ! A lot of exercises + some that were more challenging but that's why it rocks ! I could say even more exercises if included would be great and even more challenging ones ! Looking forward to starting the second part !

Awesome

Awesome course. Gives you a solid base for smart contract ethical hacking.

Great Course! Thank you for so much knowledge.

Very clear path to understand and start hands-on hacking quickly. Exercices are great and well explained.

Exercises were pretty fun and engaging and I like the hands-on approach!

I think this course was a really good purchase. Even though I already have some auditing experience. Sometimes it is more about learning how other people think, than the content itself. Anyway, it was a great experience!

Awesome course. Really loved the hands-on exercises and would recommend this to every aspiring smart contract dev or security researcher.

That's crazy! Love it!

The course really opened my eyes to bugs that I simply was not looking for in the past. Thanks!

ye

Awesome course for beginners!

Hats off to Johnny bro

Excellent exercises, very thorough. one of the best web3 dev courses available (the best imo)

Great course!

The course is well-structured, diving deep into vulnerabilities with practical examples that make complex topics easy to grasp. The hands-on approach kept me engaged, and I walked away feeling confident about applying what I learned.

I really appreciate the hands-on exercises. That really helps with understanding the concepts.

There was one challenge that stumped me (reentrancy-3), but I believe the rest were pretty straightforward with the knowledge you build up during the course and with self-exploration.

Very useful information and nicely presented

ok

This is top tier content. Worth every penny.

In my opinion It's a great course! I already had basic knowledge of solidity, but It still helped a lot!

Very happy with the classes, you explain very well

loved it!

Excellent exercises! Especially the ones for the reentrancy! The access control ones were a bit simple, but again overall excellent material!

Purchasing this course was surely one of the best decisions of my life.I want to thank Johnny Time and all the professionals who enrolled in the creation of it. It provided a lot of advantages but for me the best advantage of this course was hands-on exercises that it provides. I learnt many things from that exercises and also with the help of this course I started reading latest web3 security news and audit contest reports.Overall I highly recommend joining in this course.

Thoroughly enjoying learning from JohnnyTime and doing the exercises on my own. It is great knowledge and practice for becoming a Security Auditor

Great course content, thank you!

I was confused about my career but after completing this my goal is clear

Excellent course content! Complex concepts are taught seamlessly, and then explained in terms of how they can be exploited and how to secure against such exploits. Truly a must-take experience.

By far the best content about web3 security online.

it is really good course,required to explain briefly on reentrancy 3 and 4 Excise

Provides in depth knowledge about vulnerabilities that exist in blockchain. This is a must have if you are new to web3 security!

Love it so much!

It would be great to have more advanced topics for such a course. It was promoted as an advanced course for auditors. In reality, the first half of the course is for solidity trainees(. Owen Web3 has a lot of free advanced content. Take a look and integrate pls

Fantastic course. I have learned so much.

the 1st part is a lot a work but i learn a lot !

Awesome course but the best chapter was the reentrancy attacks where I learnt not only cei pattern but the erc777 standard for the first time. I think that another great thing on the course was having hands-on exercises at each chapter.Overall I learnt many new things even in the first part and feel so excited for the second part.I think that you are a great teacher, keep going awesome work and of course I 100% recommend this course!

Great technical content.

Thank you, JohnyTime, for the excellent course. The explanation of the theory, the design of the hands-on training, and your solution explanation are all excellent. A lot of work and thought has been put into the course, and it's very well structured, from teaching the basics of ERC20 and ERC721 at the beginning before getting into the actual attack vectors so we do not start off overwhelmed. The diagrams really helped with the more difficult-to-understand concepts.

Smooth content ,but i could find more information easily on the internet again u teach the basics well

Awwsm Course

I think it was very beneficial for beginner. I learned fungible and non-fungible tokens, several attack types and how a real-life auditor codes. My thanks to Johnny for preparing this course. Web3 is very new industry so there nearly no beginner friendly course out there. That's why I respect him very much.

love it

The Smart Contract Hacking course is self-paced, so it's really advantageous for working professionals like me who are easing themselves into a career change. The videos are fantastic and it's really refreshing to have an instructor who has personality. I've sat through other courses where you're bombarded with robotic monotonous voices that send you to sleep. Johnny is really passionate about the subject matter and it shows, which makes the course really interesting. The videos focus on relevant and up-to-date concepts. The exercises allow you to practice what's been taught, gaining valuable skills in the process, and are relevant to some of the real-world and high-profile cases. Loved part 1 and are really looking forward to part 2.

Good course! I have known much knowledge during studying this course. Thank you very much!

Nice

really good course, i learned a lot.

Fun and c00l

Most of this course is very excellent. This course helps me to know more about smart contract hacking. But some of this is very simple and easy.

I think that some of the content was similar to ethernaut, however there were also a lot of useful content and wisdom from an experienced security professional.

Thanks alot johnny . You made me from zero to some level of smart contract auditor. thanks alot.

It is overall well structured, a little too basic in this first part for my knowledge but I things will get more interesting in the second part :-)

Real time examples were great! Content seemed to be well designed in terms of difficulty. One chapter that was a bit worse wa reentrancy. Doing all other exercises I didn't need to see solution - I could handle it myself. But in reentrancy-3 I felt that no chance to spot usage of erc-777 and understand consequences without seeing the solution (I'm happy that I have gave up after just few hours :) ). The thing with registration was also hard to figure out without previous knowledge. Alse there was lack of explanation about repay function which also didn't implement check-efects-interaction pattern. I have figure out that borrowToken is pure ERC-20 thus we don't have callback so it is not exploitable but still not sure if I am right. I also would advice to introduce chapter about practical debugging with import "hardhat/console.sol"; - I have used it a lot to see how victim contract and attacking contracts are processing data, where can I enter etc.

Amazingly taught, great material

Great course! Teaches all the attacks in detail.

It was very informative!

I have just completed Part 1, and the exercises are interesting. Reentrancy tasks are even more interesting and difficult, and I'm going to review them once again. I don't think we will find arithmetic overflow and underflow vulns during the auditing process

100000000% recommended

It was really good, but with some issues in the videos regarding edition

Good course on smart contract hacking

It was fun! I'm an experienced dev, but learnt a ton, thanks.

loved it

It is the best course if we talk about smart contract security. The best part about this course is that it does not do spoon feeding instead it requires learners to learn large part themselves while doing the exercises.

I thought the course was awesome. It starts off well from the beginning and finishes by covering all the basic vulnerability cases. I'm looking forward to starting the second part as soon as possible! Thanks.

Great course! Thanks!

Awesome course!

It has been a great match for me, and I have benefited a lot from Part 1 of JohnnyTime's Blockchain Academy! Besides opening my mind on how seemingly robust smart contracts can be exploited, it has taught me better Solidity by requiring me to practice writing small chunks of code, and has made me comfortable with Hardhat. I can't wait to get my hands on Part 2 now!!

The best course I've made so far. Full of practice and well-explained

I recommend the course for the pragmatic exercises

Everything in the introductory level is explained very well.

Fantastic experience. This course has drastically elevated my abilities in Web3 and Blockchain. I feel more confident than ever in Web3 security and smart contract auditing after completing part 2 of this course.

Awesome, man :)

It is hard to believe, as good as Part 1 was, Part 2 was even better. Reviewing the various exploits and then getting real with hands-on cannot be beat. If you are on the fence about getting this class, I can definitely say that it is worth it. Johnny is a great trainer and the guest presenters toward end of curriculum are also fantastic. The content about methodology, contests, and audit DAOs toward the end gave me a lot to think about. I feel very equipped to continue growing as a smart contract auditor.

I got to know a lot about my current skill level and my depth of understanding of the subject matter. I found Part 1 quite easy as I already knew most of the topics discussed here. Just the third exercise of reentrancy was a bit difficult for me. Overall, I am super happy to have purchased this course.

Excellent material! It was nice to complete all the tasks without video

The course is very informative

Simply superb!

Fantastic course providing a solid foundation for solidity development as well as the baseline vulnerabilities faced by smart contracts.

Nice course and exercises.

very good!!

Good introduction to security. The trickier exercises were much more engaging. I would have liked a few more challenging exercises and quite a few less simple ones.

It was great

JT's Smart Contract Hacking - Part 1 course was excellent!!! I learned so much and the hands-on exercises are invaluable. As someone who has delivered technical training, I am impressed with how well the course is put together and delivered. Job well done Johnny... can't wait to get started on Part 2!

Great course

Simply EXCELENT!! loved it

Learning from someone experienced, like Johnny, is always valuable. I enjoyed the practical approach, especially the hands-on exercises for each attack vector.

Love the exercises with the walkthrough solutions 🤩

Very nice!

So far so good. It would be even greater if you add explanations for some stuff on solidity and ethers.js. For example, ``` IERC1115(token).safeTransfer(from, to, tokenId, amount, "0x"); ``` In the above function, the last param can be `[]`, but it took a quite a bit of time for me to find out why "0x" and [] are equivalent. Thank you so much for your hard work and I love the enthusiasm!

Definitely the last lesson It made me feel more confident about my job. It took me a little longer than expected to finish part one of the course but my schedule was definitely full of projects and a lot of other learning.

Good for the beginning with a lot of Basics for solidity hacking

Very nice

Super duper good

Thrilled with this JohnnyTime's Smart Contract Hacking course! (Blockchain Sec Academy) In an ecosystem getting flooded with security courses by the day, this one rises above the rest and maintains an unparalleled status. My Mentor "JohnnyTime" have created a masterpiece that not only stands out but continues to evolve, setting a standard that others can only aspire to. The depth of content, the practical insights, and the ongoing improvements make this course an invaluable resource for anyone serious about smart contract security. A big thanks to JohnnyTime and the team for delivering excellence and setting the benchmark in this field.

The course was excellent. For me, the hardest part was writing my exploits in Solidity. The descriptions of vulnerabilities, exploits, tokens, and libraries were clear and helpful. I spent about 7 days on this course, approximately 10 hours per day. It was an incredible experience. I am happy to start Part 2 right now.

I think its almost complete on the excercises part, would like to see excercises related to proxies, contract memory manipulation and logic excercises (when whats explained in the protocol isnt implemented well in the contract)

Very good explanations of all chapters.

Great course! Reentrancy 3 task was very very awesome - helped me a lot to learn about erc777 and erc1820

This course is extremely concise, the community is very active and helpful, but where this course shined for me was in the exercises, mostly the ones on reentrancy. These problems required you not only to understand the attack itself, but also the different ERCs and how these could be exploited in your favour. I also enjoyed the logic gymnastics that are not immediately recognised.

Awesome teaching approach.

Having completed the smart contract course, I'm genuinely impressed. The instructors are knowledgeable, breaking down complex concepts seamlessly. The hands-on approach and real-world examples enhance practical skills, while the course's structure accommodates all skill levels. It's a valuable investment for anyone serious about excelling in smart contract security. Highly recommended!

Amazing, very hands on! A fast track to success.

This course is fantastic. I learned so much here.

I really like this course format, easy to follow. The exercises are fun and challenging. I'm already familiar with most of the content in Part 1 and it's mostly Part 2 that I am looking forward to.

Very good to understand the concepts of different attacks.

Perfect, would be cool if subtitles are generated.

This course was a great learning experience. I had some eye-opening moments related to randomness and reentrancy attacks. It's amazing that there are so many exercises where we can practice and develop our skills.

cool.

Definitely it was a good match for me. These short videos are very comfortable !

this course is worth every cent i paid for it

This course is impressive! I thoroughly enjoy it because it offers numerous practical and challenging exercises. Highly recommended!

I'm just at the beginning of learning smart contracts dev/security and this course has been really helpfull.

awesome course

I love how this course was made. Everything is well explained and there’s practice exercises for every concept so you can make sure you get it. I highly recommend this course and I can’t wait to start part two.

A must-take for beginners delving into blockchain security. This course breaks down complex concepts into digestible modules, emphasizing hands-on challenges and real-world application. The step-by-step approach ensures an intuitive learning experience. Highly recommended for practical insights into smart contract vulnerabilities!

A thorough low-to-medium level course for introduction as smart contract auditor

Wow I loved this course!!! I found the reentrancy the hardest part (not too difficult but sometimes the hardest to create a contract to hack it). Loved the course though.

The course so far is awesome! The topics are very interesting and the exercises are very enriching!

Great course, I knew some things already but still learned a lot of new things. Guess I got to check some contracts again that I had written earlier :) Looking forward to part 2!

Really amazing course so far, even as security beginner !

Very well explained, the exercises help solidify the concepts a lot. I feel like my test writing skills improved while going through the exercises

👍

all great

I enjoyed the course, the explanation and the communication skills of Johnny are incredible. Thanks, JohnnyTime.

Super cool!

As a complete beginner, some of the Solidity code was a little over my head but your walk-thrus were great and made it really easy to follow the contracts. I thought the course was very comprehensive, with lots of hands-on experience in writing Solidity smart contract code and tests using the Hardhat Framework. I would highly recommend this course for anyone looking to get into Web3 security and smart contract security.

I learned a lot. I've got the foundation to kick off my career as a Smart Contract Auditor. Thank you so much!

I loved everything about part 1, it was quite easy to jump on it and the exercises helped me a lot to get hands-on experience in exploiting the exercise controls. Thank you, Johnny.

This Course is simply AMAZING

very informative and most importanly has great practical exercises, I wish all courses would be like this one. The best money investment I did.

Very basic, also hardhat is very close to being unusable. It is better to introduce Foundry directly

This was amazing! Perfect for getting into Blockchain security!

This was amazing! Perfect for getting into Blockchain security!

Amazing Course!. Its in a different league. Learnt a ton!

Amazing Course!

I think the course is great for someone new to Solidity and EVM, the information and the way it's explained is grat and the structure seems good, but for me it was nothing new, sadly.

loved part 1 learned a lot from this

Super nice course. Really liked the exercises. Recommended

Great Course!

:)

This Course is simply amazing.

This part of the course has lots of fantastic hands-on exercises. Love it!

Amazing course! I learned so much! Especially I liked the frontrunning part and AttackLendly (oracle manipulation 2) where everything came together in a beautiful multi stage attack. Part 2 is much more advanced and insightful than Part 1. Looking forward to even more advanced and sophisticated attacks! Thank you Johnny and the guests for sharing your great knowledge!

Value-packed content with crystal clear explanation of the necessary attacking vector. Intensive mind-boggling exercises to strengthen hacker mindset exploiting smart contracts. Most insightful and beginner-friendly course available in market

Great course with terrific explanations. Fastest way to upskill your security knowledge.

Really good and complete course! Thank you!

Great content!

I am so happy for this course that I have no words! Definitely worth its money! I would even pay 1000$ for such a good course! The second part is even better! I feel super privileged to be a student of this course! Thank you JohnnyTime! I love you and all the team behind this course! I mean it!

Its a really good introduction to basic of blockchain and mostly used ERC standard and basic vulnerabilities. Thanks johnny.

Good content overall. I like the reentrancy part the most. The access control is also a good reminder about simple programming error existing in the wild.

Definitely the best auditing course on the market!

Greate course!!!

very good ! very well explained !

good

good content part 1 is mostly for beginners though

Awsome...

:)

Best course on the subject so far, no doubt it is second to none! Thank you Johnny!

Too bad there aren't 10 ⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️⭐️s coz this is definitely a double 5 ⭐️

Good enough for newbie.

Recommended.

Full of information and well presented. Great course to keep my learning focused.

Wonderful! Learnt a lot!!

The only practical hacking course in the space! Totally happy with the content!

Few of the re-entrancy techniques were new for me "hands on" exercises were definitely helpful, gave me a grip on writing tests Multiplication overflow was also new for me. Eagerly waiting for the next part

Amazing course! 5/5