Hello, I'm GymCoding!

These days, new AI coding tools are being released every week. Cursor, Copilot, Gemini, Claude Code, Codex… Many people find that even when they switch tools, the results don't change significantly.

The AI Cheat Key Week event is currently being held at Inflearn, and Claude Code Perfect Mastery is currently 30% off. The discount ends exactly 9 days from now at midnight, so I wanted to let you know in advance!

Key Highlights of This Course

• Learning accurate specifications based on official Claude Code documentation (a systematic approach, not a collection of random blog posts)

• How to internalize proven real-world development workflows into your own work vào công việc của bản thân.

• Bonus: The Three Major Engineering Pillars: Prompt / Context / Harness về Prompt / Context / Harness

You can learn how to use the tools in just an hour on YouTube. However, simply gathering fragmented tips will eventually lead to a plateau. The two pillars—official specifications and proven workflows—are the real "cheat codes." It is no coincidence that Inflearn is calling this event AI Cheat Code Week.

👉Enroll now at a discounted price

🎯 To those who haven't taken the course yet

Now, it is no longer a matter of whether you use AI coding tools or not, but an era where how well you utilize them makes the difference in skill.

Since its launch, 7,000 people have taken the course together, maintaining a 4.9 rating with 802 reviews. Not only developers, but also marketers, planners, researchers, and data analysts from various professions are taking this course for the purpose of work automation.

"I hesitated a lot about taking this course because of the price. As a job seeker preparing for an infrastructure-related role, I also wondered if there would be much I could gain from this course.

After taking the course, I have been refactoring the service I was previously building, and I am applying the workflows taught in the lectures to my actual work by utilizing not only Claude Code but also Codex. Thanks to this, I am learning a lot more about how to improve the efficiency of my workflow rather than just how to use the tools themselves."

— Job seeker preparing for an infrastructure role, 5-star course review

This AI Cheat Key Week 30% discount ends in 9 days at midnight.

👉Enroll before the discount ends

Thank you! 🙇‍♂

Hello, I'm GymCoding!

"I keep getting errors while trying to install Claude Code."
"It's my first time using a terminal, so I feel lost just looking at the black screen."
"I managed to install it, but now I don't know what to do first."

Since launching the course over five months ago, the most frequent questions I've received have been regarding installation and first-time use. That's why I've newly organized and added a complete workflow for Claude Code beginners based on the latest version!

This lecture is not just a video where you simply follow installation commands. It is designed so that even those new to the terminal can install Claude Code without fear and experience completing their first app all at once.

What is covered in this lecture

• Payment Plan Selection Guide — Pro Plan vs. Max Plan, which one should you choose?

• Terminal & CLI Concepts — Explanations that even beginners can understand at once by comparing them with GUI

• Native Installation by OS — macOS / Windows (PowerShell) + Git Bash

• Installation Troubleshooting — Environment variable settings, the most common hurdle (for both Windows and Mac)

• VS Code Integration + Model Change (Sonnet) — Settings for convenient use while saving tokens

• First Practice: Creating a Today's Fortune Web App — Experience a proven AI development workflow: Explore → Plan → Implement

The core of this lecture is for even those new to Claude Code to follow along comfortably and experience the moment their first app is completed!

👉Go to Lecture

😊 To those currently taking the course

This additional session is available to existing students at no extra cost. It will be helpful for both those who were stuck at the installation stage and those who want to organize everything from the beginning once more.

And if the lecture was helpful, even a single line of review is a huge source of strength. If you haven't left a review yet, I would be grateful if you could leave a short one! 🙏

👉Write a course review

🎯 For those who haven't taken the course yet

Now, it is no longer a matter of whether you use AI coding tools or not, but an era where how well you use them defines the difference in skill.

Within just 5 months of its release, over 6,800+ people have enrolled, and a wide range of individuals—not only developers but also non-developers such as marketers, planners, researchers, data analysts, and students—are learning Claude Code together.

Hello, I am a marketer, not a developer.
I felt the limitations of using only GPT, so I started looking for Claude Code lectures. At first, I hesitated, thinking this might be for developers only, but this was the first lecture that made me feel it truly works even for non-developers...
👉 Original Review

Learn how to properly study Claude Code based on official documentation and integrate it into a proven AI development workflow all at once.

👉Enroll now at a special discount price

Thank you! 🙇‍♂

Hello, I'm GymCoding!

• "I'm so overwhelmed by the cost of Claude Code tokens"

• I've been getting so many questions like, "I don't know where my tokens are leaking."

So, I’ve put together an additional lecture to properly address this!

This lecture is not just about simple token-saving tips. It is a practical guide that selects only 4 plugins directly related to token saving from the 171 plugins in the Anthropic official marketplace, covering everything from measurement to automatic blocking in one go.

What we will cover in this lesson

• Where tokens are leaking shown on one screen: How to use session-report — How to analyze token usage by project and prompt, and identify the most expensive prompts using an HTML dashboard

• How to reduce the token tax on every turn using two tools from CLAUDE.md management (revise + improver) to keep your claude-md-management clean, which automatically attaches to every request

• serena MCP, which searches for code by meaning rather than just characters — from the reason it was picked as the #1 tool for saving tokens to installing uv package manager dependencies

• hookify, which prevents Claude's mistakes in advance — among the four, this is the only official tool that goes beyond simple token saving to assist with the core of harness engineering

• The entire workflow to install and activate all four with a single-line command from the Anthropic official marketplace

The core of this lecture is a bundle of practical tools that will help you save tokens using official tools curated directly by Anthropic, and even reach harness engineering with the final one!

👉 Go to the lecture!

😊 To those currently enrolled

Those who are taking the Claude Code Perfect Master course can take the new lecture immediately at no additional cost. It has been added to the end of Section 30 of the existing curriculum, so please check it out!

And if the lecture was helpful, a single line of review would be a huge help. If you haven't left a review yet, I would appreciate it if you could leave even a short one! 🙏

👉 Write a course review

🎯 For those who haven't taken the course yet

Now, it is no longer a question of whether you use Claude Code, but an era where how efficiently you use tokens makes the difference in cost and results.

Within 6 months of release, over 6,600 people are taking the course, and a wide range of individuals, including not only developers but also marketers, data analysts, students, and non-developers, are participating.

Recent Reviews

This is the most meaningful lecture of my life. This is the first time I've seen an IT lecture that is so sincere and updated in real-time, and it will probably be the last. It truly is the best lecture, and I want to recommend it to everyone.

You can now enroll at a special discount price at gymcoding.co/vip. Please be sure to check it out before the discount ends!

👉 Enroll now at a special discount price (gymcoding.co/vip)

Thank you! 🙇‍♂

Hello, this is Gym Coding!

Lately, I've been posting card news on Instagram, Threads, and YouTube communities. Many people have been commenting, asking, "How do you make these?" or saying, "You're really good at making card news."

So I am preparing a proper video about it! To give you the conclusion first, these card news are all being created using Claude code.Without any separate design tools or AI image generators, it's possible with just a Claude subscription for 0 won in additional fees.

The core of this lecture is "direct control instead of outsourcing" — it's not about leaving it to AI and getting different results every time, but about controlling it with rules to systematically produce consistent results!

I plan to upload it as an additional lecture tomorrow (April 21st). For those taking this course, I will provide the actual card news HTML source I use along with card news creation skills, so you can apply them directly to your own brand's card news instead of just watching the video!

👉View card news examples on Gym Coding Instagram

😊 To those currently enrolled

Those who are currently taking the Claude Code Complete Master course can watch the new lecture immediately at no additional cost. It will be added to the existing curriculum tomorrow, so please check it out.

And if the lecture was helpful, a single line of review would be a huge help. If you haven't left a review yet, I would be grateful if you could leave even a short one! 🙏

👉Write a course review

🎯 For those who haven't taken the course yet

Now is an era where the difference in skill is determined not by whether you use AI coding tools, but by how well you use them.

Since its launch, more than 4,700 people have taken the course, and a wide range of people, including not only developers but also marketers, data analysts, students, and non-developers, are joining us.

I am a complete beginner who knows nothing about development. At first, I started developing with ChatGPT without watching any lectures or having any information. Then, I moved on to Cursor and realized the Claude model is excellent, so I am currently about to start developing with Claude.
I happened to learn about Gym Coding's lectures through someone nearby, and after listening to them, I thought, "I've really been doing this without any plan at all." I feel that after completing this course, I will be able to develop in a more systematic way with a higher level of understanding. Also, the continuous lecture updates!!! I think they will be a huge help. Thank you!^^
— Original Link

You can now enroll at a special discount price at gymcoding.co/vip. Please make sure to check it out before the discount ends!

👉Enroll now at a special discount (gymcoding.co/vip)

Thank you! 🙇‍♂

Hello, I'm GymCoding!

I'm sure everyone has experienced a time when the same AI model works well once but performs poorly another time. Those moments when you wonder why the results are so different even though you used a similar prompt, whether the model is the problem, or if you're missing something.

I feel like many people have been having these concerns lately. So, I've properly organized everything in this additional lecture!

This lecture is not just about prompt tips. I will systematically explain, along with the latest research cases, how the results change completely depending on how you design the environment in which the AI works, even when using the same AI model.

What is covered in this lecture

• Exactly what harness engineering is and why it is gaining attention now

• Anthropic's actual experimental cases — a ruined app for $9 vs. a completed app for$200 with the same model, and what the difference was.

• 3 causes of AI agent errors (Memory loss between sessions, Context Anxiety, Self-Evaluation)

• CLAUDE.md, Permissions, Hooks, MCP, to Subagents — 6 components for designing a harness in Claude Code

• How to re-evaluate harness rules as models evolve

The core of this lecture is not to blame the AI, but to create an environment where the AI can work effectively!

👉Go to the lecture!

😊 To those currently enrolled

Those who are taking the Claude Code Perfect Master course can watch the new lecture immediately at no additional cost. It has been added to the end of the existing curriculum, so please check it out.

And if the lecture was helpful, a single line of review would be a huge help. If you haven't left a review yet, I would appreciate it if you could leave even a short one! 🙏

👉Write a course review

🎯 For those who haven't taken the course yet

Now, we are in an era where the difference in skill is determined not by whether you use AI coding tools, but by how well you use them.

Since its release, over 5,500 people have taken the course, and a wide range of individuals, including not only developers but also marketers, data analysts, students, and non-developers, are participating.

"I am a complete beginner who knows nothing about development.At first, I started developing with ChatGPT without watching any lectures or having any information. Then I moved to Cursor and felt that the Claude model was great, so I am currently at the stage of starting development with Claude. I happened to find out about Gym Coding's lectures through someone nearby, and after listening to them, I thought, 'I have really been doing this without any plan at all.' I feel that after completing this course, I will be able to develop in a more systematic way with a higher level of understanding. Also, the continuous lecture updates!!! I think they will be a huge help. Thank you!^^ " — LExxxx

You can now enroll at a special discount price at gymcoding.co/vip. Please make sure to check it out before the discount ends!

👉Enroll now at a special discount price

Thank you! 🙇‍♂

Hello, I'm GymCoding!

Harness Engineering is becoming a hot topic, and many people are curious about what exactly it is!

I am currently planning this as an additional lecture.

Harness Engineering is not a new technology. It is a method for systematically designing things you are already using, such as CLAUDE.md, Hooks, and Permissions.

The core point is "change the environment before you change the model." Even with the same Claude, the results vary completely depending on the environment design.

I will be uploading it as an additional lecture soon.

😊 To those currently taking the course

The additional lectures will be provided to existing students at no extra cost.

And if the lecture was helpful, a one-line review would be a huge source of strength. If you haven't left a review yet, I would be grateful if you could leave a short one! 🙏

👉Write a course review

🎯 For those who haven't taken the course yet

Now, we are in an era where the difference in skill is determined not by whether you use AI coding tools, but by how well you use them.

Within just 4 months of its release, more than 5,000 people have taken the course, and a wide range of individuals, including not only developers but also marketers, data analysts, students, and non-developers, are participating.

Recent Reviews

I've taken dozens of courses on Inflearn, but this course was on another level. It's absolutely insane!!
I've watched a few Claude Code-related lectures on YouTube and Inflearn, but this is the first time I've seen a course that covers everything so systematically, from the basics to the latest updates. It was really impressive how it didn't just stop at introducing features but also pointed out why things are used this way. I am confident that it will be of practical help to everyone, from those who know nothing about Vibe Coding to those who already have experience.
...
Even though I only applied a part of this course, my development speed and depth have completely changed. It's not just about coding fast; I feel like the level of design itself has improved. I truly felt like I had grown wings.

...
To be honest, it's so good that I almost want to keep it to myself, but I still highly recommend it. I will definitely buy Gym Coding's new lectures as soon as they are released. I've already purchased the Next.js and React courses as well. I would be grateful if you continue to create more lectures like this in the future!

View original review

And right now, we are having a 25% discount on all courses to celebrate reaching 5,000 students! This discount is only valid until midnight tonight. Many people contacted me saying they missed the previous discount, so I'm making sure to let you know this time.

👉Enroll now at the discounted price

Thank you! 🙇‍♂

Hello, I'm GymCoding!

As the project grows, CLAUDE.md grows with it, causing Claude to follow the wrong rules... I'm feeling the limits of trying to manage everything with a single CLAUDE.md in a monorepo...

I've noticed many people have been sharing these concerns lately. So, I've put together a proper explanation in this additional lecture!

This lecture is not just a tip for splitting CLAUDE.md into multiple files. It is a proven strategy that allows Claude to automatically read manuals only when working on a specific folder by dividing them accordingly.

What is covered in this lecture

• The core principle of sub-CLAUDE.md — a structure that automatically loads only when working in that specific folder

• Umbraco CMS Real-world Case Study — How to manage large-scale projects with 23 CLAUDE.md files

• Braintree/PayPal Real-world Case Study — 26 CLAUDE.md Operation Patterns by Payment Feature

• .claude/rules/ vs sub-directory CLAUDE.md — Comparison table on when to use which

• File Size Guidelines — The 30-line root CLAUDE.md case study from CopilotKit (29K ⭐)

The core of this lecture is not about reducing rules, but how to make only the rules of the folder you are currently working in visible to Claude!

👉Go to the lecture!

😊 To those currently taking the course

Existing students can take this additional lecture immediately at no extra cost!

If the lecture was helpful, a single line of review would be a huge help. If you haven't left a review yet, I would appreciate it if you could leave even a short one! 🙏

👉Write a course review

🎯 For those who haven't taken the course yet

We are now in an era where the difference in skill is determined not by whether you use AI coding tools, but by how well you use them.

Within just 4 months of its release, more than 4,500 people are taking the course, including not only developers but also a wide range of individuals such as marketers, data analysts, students, and non-developers.

Recent Reviews

This is just insaneThere are so many things I didn't know. Honestly, there's a lot to study, but the instructor explains it so easily and it's very useful. Highly recommended, for real.

To celebrate surpassing 4,000 students within just 4 months of launch, all Gym Coding courses are currently 25% off. This is the maximum discount rate a knowledge sharer can set. It runs only until 4/6 (Mon), so don't miss out!

👉Enroll now at a discounted price

Thank you! 🙇‍♂~~!!

Hello, this is Gym Coding!

The Claude Code Master course has surpassed 4,000 students within just 4 months of its release.

A truly diverse range of people, including not only developers but also marketers, planners, and non-majors, have joined us.

I feel with every course review that these numbers didn't just accumulate on their own. I am truly grateful 🙏

I prepared this because I wanted to convey my gratitude in the most direct way possible.

📌 Gym Coding All Courses 25% Discount Event

📌Running for exactly 2 weeks, from 3/23 (Mon) to 4/6 (Mon) at midnight

👉Enroll now at a discounted price

✅ If you haven't taken the Claude Code course yet

There's a reason why 4,000 people chose it.

• Lifetime Free Updates — AI changes every week, and the lectures keep up with it.

• Complete 4 Real-world Projects — By the end of the course, you'll have 4 services built with your own hands

• Learning Based on Official Documentation — Based on Anthropic's official documentation, ensuring information reliability

Recent Course Reviews

In the first session, I couldn't understand what was being said at all, nor could I grasp the purpose or meaning behind why things had to be done that way.

From the second session, I gradually became more familiar with it, became able to carry out projects on my own, and could proceed by finding the necessary parts as needed.

By the 3rd round, I was watching with a full understanding, so unlike the difficult 1st round, I was able to enjoy the lectures.

It's okay even if you've never used Claude Code before. We will go through it step-by-step from the very beginning.

👉View Course Reviews

✅ For those already taking the Claude Code course

I recommend taking this opportunity to watch the React / Vue / Next.js lectures together.

The more you understand frameworks, the more you can utilize AI coding tools to their full potential.

The synergy is different when viewed together.

👉View all Gym Coding courses

I am always grateful 🙇‍♂

Best regards, Gym Coding