Workflow-Based Techniques for Handling High-Volume Traffic with a Kakao Interviewer

If you’ve found it difficult to explain what’s happening under the hood while using AI and embeddings, this course may be the answer. Drawing on the experience of a practicing AI developer in Silicon Valley, it helps you understand the principles of AI through code by implementing everything from embeddings and Word2Vec to automatic differentiation and transformers yourself.

If you’ve ever had trouble determining whether the quality of responses declined after changing a prompt or model while building a service using an LLM, this course may be the solution. You’ll learn how to create your own evaluation criteria and automatically identify responses that have changed.

When Redis alone can no longer guarantee performance, what options do we have?? There is Valkey, which is 100% compatible with Redis and applies IO-based tuning. Through this course, let’s explore how Valkey guarantees 1M++ TPS and learn about the data structures suited to different traffic patterns and feature implementations.

You know about AI agent frameworks, but understanding how they work and applying them in practice can be difficult, right? Drawing on firsthand experience from Silicon Valley, we’ll guide you from the core principles to practical applications.

The limitations of LLMs? I’ll share practical solutions to real-world problems based on RAG trial and error and operational know-how from working in Silicon Valley.

This course goes beyond basic CRUD-level database usage, helping you develop the PostgreSQL skills needed in the AI era from a practical, real-world perspective. Drawing on AI development experience in Silicon Valley, you’ll gradually learn how to design and use JSON, indexes, transactions, and pgvector in actual services, while gaining the skills to solve complex data structure and performance problems.

A Redis course created with a current Kakao interviewer. From hands-on practice with data structures ranging from String to Sorted Set to Sentinel and cluster configuration, you’ll build design rationale that holds up in interviews and real-world work.

This course goes beyond teaching Docker as merely a set of tools and approaches it from the perspective of solving the concerns and problems you will actually encounter in the field. It explains, based on firsthand experience operating financial infrastructure in the industry, everything from unpredictable errors caused by differences between development and production environments, and configuration mistakes stemming from vague concepts of images and containers, to the anxiety of wondering, “How much do I need to know for this to be useful in practice?” Rather than simply listing commands, the course focuses on real-world examples to explain why this structure is necessary, how to design images for easier maintenance, and how to manage containers to operate services reliably. In particular, it places greater emphasis on hands-on practice than theory, with the goal of helping students understand Docker visually and master it through practice—not merely reaching the level of “knowing how to use Docker,” but understanding it from an operational perspective. This course provides practical standards and direction for those encountering Docker for the first time, those who have used it but have not yet organized their understanding of the concepts, and developers who want to take their infrastructure skills to the next level.

It was created to solve the problem of “not knowing where or how to start with Kubernetes.” Based on hands-on experience gained from operating financial infrastructure, it is structured to help learners understand Kubernetes by following the actual process of building and operating it, rather than focusing on theory alone. Through a learning progression covering its relationship with Docker, YAML, Pods, Deployments, and Services, learners will internalize Kubernetes not as a “concept,” but as a “usable technology.”

This course covers RPC communication techniques for maximizing performance in large-scale MSA (Microservice Architecture) environments. Going beyond simple gRPC practice, you will learn how to implement stable and efficient service-to-service communication in real-world production environments where hundreds of microservices operate simultaneously. Based on Golang, the course takes a practical, hands-on approach to writing Protocol Buffers (proto) syntax, generating code automatically and implementing services, understanding gRPC’s architecture and advantages over traditional RPC, and applying performance optimization strategies. To ensure that even non-majors and beginners in server development can easily follow along, it explains everything step by step—from the concept of RPC to gRPC’s internal operating principles—helping you develop practical skills that can be applied directly to real-world services.

Learn the process of building essential observability in a microservices architecture (MSA) environment, from the basics to hands-on practice. Through step-by-step exercises, you will learn standardized data collection using OpenTelemetry, trace storage and search with Grafana Tempo, and visualization using TraceQL. You will also learn how to trace service flows through distributed tracing, identify bottlenecks, and analyze the causes of failures.

From the fundamentals of MySQL usage to the advanced techniques required in real-world service environments, you will learn progressively. The course also covers a wide range of topics, including data modeling techniques based on various cases and practical data, evaluating the effectiveness of Foreign Key design, analyzing the Google Calendar schema DDL, and modern DDL design principles. It provides an in-depth understanding of how to use MySQL as a core component of a system, rather than merely as a database.

This course is a master class that systematically covers the fundamental principles and practical applications of MongoDB. Starting with core MongoDB concepts, you will systematically learn essential topics for practical work, such as database design, CRUD operations, indexing, aggregation pipelines, performance optimization, transactions, and security. It explains topics step-by-step so even beginners can understand, and you can deeply learn the working principles of MongoDB through exercises and examples. This is the best introductory and practical course for developers who want to build strong MongoDB skills for practical work.

This course is for developers who want to find fundamental solutions in environments where response times slow as traffic increases, thread pools are quickly exhausted, and bottlenecks become more severe as the number of external API calls grows. Rather than simply scaling up servers, it helps you look at these problems from the perspective of changing the underlying architecture itself. Through this course, you will first understand the limitations of the traditional Spring MVC thread-per-request model. You will examine at the code level why throughput fails to increase even when CPU resources remain available, and how blocking I/O actually occupies system resources. Next, you will learn the concepts and standard specifications of Reactive Streams, as well as how to handle data streams using Reactor’s Mono and Flux. Rather than focusing solely on basic usage, you will gain hands-on experience with how data flows begin and are consumed, and how throughput is controlled. In particular, you will implement designs that use back pressure to prevent OOM conditions and overload. You will also learn how Spring WebFlux’s event-loop-based processing structure works and conduct comparative exercises to see how non-blocking I/O operates during actual request processing. By examining MVC and WebFlux side by side, you will identify their structural differences and establish criteria for deciding when to choose Reactive. This course goes beyond simply “learning asynchronous programming.” You will learn how to handle more requests with fewer threads, maintain stable flows in environments with heavy reliance on external APIs, and develop the design instincts needed to achieve high throughput in highly concurrent environments.

Build a Kafka cluster with Spring Boot 3.x + Kotlin, and develop a scalable order processing system capable of real-time event streaming using PostgreSQL CDC, Debezium Connect, and Apache Avro schemas.

Learn the SAGA transaction management technique for maintaining data consistency in distributed environments through a hands-on approach. You will configure three microservices using Spring Boot and Docker, and implement both Orchestration and Choreography patterns using Kafka and MySQL. Through this course, you will master core concepts applicable to real-world scenarios, including the operational principles of distributed transactions, designing compensating transactions, and handling fault recovery.

This course covers how to set up multi-module projects from scratch using Kotlin and Spring Boot. It proceeds with a hands-on approach, covering everything from the basic concepts of modularization to Gradle configuration, managing dependencies between modules, and actual application development. If you are a beginner or intermediate developer looking to learn the fundamentals and practical application of multi-modules, please refer to this course.

The biggest challenges when operating a batch system that processes millions of records are performance degradation and the difficulty of recovery when failures occur. Simple loops or poor design cannot solve these problems. In this course, based on experience handling large volumes of data reliably in real-world service environments, you will learn the architecture and operating principles of Spring Batch, along with design methods that achieve both performance and stability. Going beyond a simple explanation of its features, this course helps you develop fundamental problem-solving skills for data processing through practical batch architectures that can be applied directly in the workplace.

Learn how to design and process large-scale data architectures capable of handling hundreds of billions of records, using only pure SQL and MySQL’s core features, alongside a Toss developer who handles hundreds of billions of financial transactions and a developer who started without a computer science background and now works on platform development in Pangyo.

This course is a master class that teaches Kotlin's 🌺 Coroutine, covering everything from theoretical foundations to practical application in a standard manner. It systematically covers core principles and structure, the necessity of asynchronous programming, Coroutine builders and scopes, exception handling, channels, Flow, and other key features frequently used in practice, step by step. Each concept is explained with hands-on examples, making it easy for beginners to understand and immediately apply them. This is the best introductory and practical course for developers who want to build strong Coroutine skills for real-world use.