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## 📰 About the Publication

Welcome to [The Main Thread](https://www.the-main-thread.com/) — your strategic companion for navigating the evolving world of enterprise Java, software architecture, and AI-infused systems.

- Build fast, cloud-native apps with **Quarkus**
- Secure microservices with **Vault**, TOTP, and secrets management
- Integrate **LangChain4j** and **AI services** into Java applications
- Design resilient, scalable systems using **Kubernetes** and **Dev Services**
- Understand modern patterns like **RAG (Retrieval-Augmented Generation)**, validation layers, and service guardrails

All content is hands-on, enterprise-relevant, and written for people building real systems—not prototypes.

## 🧑‍💻 What's in This Repo

Each folder in this repository matches an article from the Substack and includes:

- ✅ Complete project setups
- 💡 Example code with comments
- ⚙️ Quarkus configurations and Dev Services integration
- 📦 Maven projects you can run locally with Podman, Ollama, PostgreSQL, etc.

## Build Status

| Project | Java | Quarkus | Tests | Links | Build Status |
| :--- | :---: | :---: | :---: | :---: | :--- |
| **age-everywhere** | - | - | - | Article | ![age-everywhere](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/age-everywhere.json) |
| **ai-design-critic** | - | - | - | Article | ![ai-design-critic](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-design-critic.json) |
| **ai-detector** | - | - | - | Article | ![ai-detector](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-detector.json) |
| **[ai-document-assistant](https://github.com/myfear/ejq_substack_articles/tree/main/ai-document-assistant)** | 21 | 3.29.4 | - | [Article](https://www.the-main-thread.com/p/quarkus-langchain4j-ai-document-assistant) | ![ai-document-assistant](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-document-assistant.json) |
| **ai-dungeon-master** | - | - | - | Article | ![ai-dungeon-master](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-dungeon-master.json) |
| **ai-email-simulator** | - | - | - | Article | ![ai-email-simulator](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-email-simulator.json) |
| **ai-error-handler-pii** | - | - | - | Article | ![ai-error-handler-pii](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-error-handler-pii.json) |
| **ai-memory** | - | - | - | Article | ![ai-memory](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-memory.json) |
| **[ai-progress-tracker](https://github.com/myfear/ejq_substack_articles/tree/main/ai-progress-tracker)** | 21 | 3.28.2 | - | [Article](https://www.the-main-thread.com/p/quarkus-langchain4j-granite4-ai-progress-tracker) | ![ai-progress-tracker](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ai-progress-tracker.json) |
| **api-adapter-demo** | 21 | 3.30.1 | ✅ 4/4 | [Article](https://www.the-main-thread.com/p/quarkus-stripe-api-versioning-adapter-java-tutorial) | ![api-adapter-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/api-adapter-demo.json) |
| **archunit-bce** | - | - | - | Article | ![archunit-bce](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/archunit-bce.json) |
| **banner-studio** | 21 | 3.29.4 | - | Article | ![banner-studio](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/banner-studio.json) |
| **[blog-search](https://github.com/myfear/ejq_substack_articles/tree/main/blog-search)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-postgresql-full-text-search-tutorial) | ![blog-search](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/blog-search.json) |
| **[carbon-quarkus](https://github.com/myfear/ejq_substack_articles/tree/main/carbon-quarkus)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-carbon-design-system-dashboard-tutorial) | ![carbon-quarkus](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/carbon-quarkus.json) |
| **[christmas-card](https://github.com/myfear/ejq_substack_articles/tree/main/christmas-card)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-java-christmas-card-generator-renarde-tutorial) | ![christmas-card](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/christmas-card.json) |
| **[claims-intake](https://github.com/myfear/ejq_substack_articles/tree/main/claims-intake)** | 21 | 3.30.5 | - | [Article](https://www.the-main-thread.com/p/event-driven-claims-pipeline-java-quarkus-kafka) | ![claims-intake](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/claims-intake.json) |
| **[countdown-orchestrator](https://github.com/myfear/ejq_substack_articles/tree/main/countdown-orchestrator)** | 21 | 3.30.2 | - | Article | ![countdown-orchestrator](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/countdown-orchestrator.json) |
| **[data-oriented-quarkus](https://github.com/myfear/ejq_substack_articles/tree/main/data-oriented-quarkus)** | 21 | 3.30.3 | ✅ 1/1 | [Article](https://www.the-main-thread.com/p/data-oriented-programming-java-quarkus) | ![data-oriented-quarkus](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/data-oriented-quarkus.json) |
| **[enterprise-rag-secure](https://github.com/myfear/ejq_substack_articles/tree/main/enterprise-rag-secure)** | 21 | 3.30.3 | - | Article | ![enterprise-rag-secure](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/enterprise-rag-secure.json) |
| **enterprise-rag** | - | - | - | Article | ![enterprise-rag](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/enterprise-rag.json) |
| **[event-sourcing-quarkus](https://github.com/myfear/ejq_substack_articles/tree/main/event-sourcing-quarkus)** | 21 | 3.30.2 | ✅ 2/2 | Article | ![event-sourcing-quarkus](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/event-sourcing-quarkus.json) |
| **[feature-key-service](https://github.com/myfear/ejq_substack_articles/tree/main/feature-key-service)** | 21 | 3.30.5 | - | [Article](https://www.the-main-thread.com/p/quarkus-api-key-feature-level-access-control) | ![feature-key-service](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/feature-key-service.json) |
| **fleet-insure** | 21 | 3.29.4 | - | Article | ![fleet-insure](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/fleet-insure.json) |
| **[food-delivery](https://github.com/myfear/ejq_substack_articles/tree/main/food-delivery)** | 21 | 3.30.2 | - | Article | ![food-delivery](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/food-delivery.json) |
| **[htmx-tasks](https://github.com/myfear/ejq_substack_articles/tree/main/htmx-tasks)** | 21 | 3.30.4 | - | [Article](https://www.the-main-thread.com/p/htmx-quarkus-server-rendered-ui-java) | ![htmx-tasks](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/htmx-tasks.json) |
| **[jigsaw-puzzle](https://github.com/myfear/ejq_substack_articles/tree/main/jigsaw-puzzle)** | 21 | 3.30.4 | - | [Article](https://www.the-main-thread.com/p/java-quarkus-image-processing-jigsaw-puzzle-rest-api) | ![jigsaw-puzzle](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/jigsaw-puzzle.json) |
| **[lean-dashboard](https://github.com/myfear/ejq_substack_articles/tree/main/lean-dashboard)** | 21 | 3.30.5 | - | [Article](https://www.the-main-thread.com/p/lean-business-ui-quarkus-qute-no-javascript) | ![lean-dashboard](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/lean-dashboard.json) |
| **metadata-stripper** | 21 | 3.29.4 | ✅ 4/4 | Article | ![metadata-stripper](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/metadata-stripper.json) |
| **[mtls-client-cert-guard](https://github.com/myfear/ejq_substack_articles/tree/main/mtls-client-cert-guard)** | 21 | 3.30.5 | - | [Article](https://www.the-main-thread.com/p/quarkus-mtls-client-certificate-validation-java) | ![mtls-client-cert-guard](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/mtls-client-cert-guard.json) |
| **[multi-tenant-api](https://github.com/myfear/ejq_substack_articles/tree/main/multi-tenant-api)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-multi-tenant-api-nipio-tutorial) | ![multi-tenant-api](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/multi-tenant-api.json) |
| **[nfl-game-predictor](https://github.com/myfear/ejq_substack_articles/tree/main/nfl-game-predictor)** | 21 | 3.30.1 | ✅ 2/2 | Article | ![nfl-game-predictor](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/nfl-game-predictor.json) |
| **[ooo-generator](https://github.com/myfear/ejq_substack_articles/tree/main/ooo-generator)** | 21 | 3.30.3 | - | [Article](https://www.the-main-thread.com/p/java-out-of-office-generator-quarkus-langchain4j-ollama) | ![ooo-generator](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/ooo-generator.json) |
| **[order-workflows](https://github.com/myfear/ejq_substack_articles/tree/main/order-workflows)** | 21 | 3.30.4 | - | [Article](https://www.the-main-thread.com/p/quarkus-temporal-long-running-workflows-java) | ![order-workflows](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/order-workflows.json) |
| **[pixel-art-converter](https://github.com/myfear/ejq_substack_articles/tree/main/pixel-art-converter)** | 21 | 3.30.3 | ✅ 1/1 | Article | ![pixel-art-converter](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/pixel-art-converter.json) |
| **polymorphic-json** | 21 | 3.29.0 | ✅ 2/2 | [Article](https://www.the-main-thread.com/p/quarkus-jakarta-data-polymorphic-json) | ![polymorphic-json](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/polymorphic-json.json) |
| **[product-catalog](https://github.com/myfear/ejq_substack_articles/tree/main/product-catalog)** | 21 | 3.30.5 | ✅ 1/1 | Article | ![product-catalog](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/product-catalog.json) |
| **[qr-designer](https://github.com/myfear/ejq_substack_articles/tree/main/qr-designer)** | 21 | 3.30.2 | - | Article | ![qr-designer](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/qr-designer.json) |
| **quarkus-actuator** | 21 | - | - | Article | ![quarkus-actuator](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/quarkus-actuator.json) |
| **[quarkus-docling-converter](https://github.com/myfear/ejq_substack_articles/tree/main/quarkus-docling-converter)** | 17 | 3.36.0 | ✅ 1/1 | Article | ![quarkus-docling-converter](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/quarkus-docling-converter.json) |
| **[quarkus-jqassistant-demo](https://github.com/myfear/ejq_substack_articles/tree/main/quarkus-jqassistant-demo)** | 21 | 3.30.3 | ✅ 12/12 | [Article](https://www.the-main-thread.com/p/quarkus-jqassistant-architecture-rules-java) | ![quarkus-jqassistant-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/quarkus-jqassistant-demo.json) |
| **[quarkus-protobuf-demo](https://github.com/myfear/ejq_substack_articles/tree/main/quarkus-protobuf-demo)** | 21 | 3.30.1 | ✅ 3/3 | Article | ![quarkus-protobuf-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/quarkus-protobuf-demo.json) |
| **recursive-comments** | 21 | 3.29.4 | ✅ 6/6 | Article | ![recursive-comments](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/recursive-comments.json) |
| **[request-filter-demo](https://github.com/myfear/ejq_substack_articles/tree/main/request-filter-demo)** | 21 | 3.30.3 | ✅ 1/1 | Article | ![request-filter-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/request-filter-demo.json) |
| **resource-reader** | 17 | 3.22.1 | - | Article | ![resource-reader](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/resource-reader.json) |
| **[santa-cli](https://github.com/myfear/ejq_substack_articles/tree/main/santa-cli)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-java-holiday-cli-tutorial-santa-cli) | ![santa-cli](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/santa-cli.json) |
| **[secret-santa](https://github.com/myfear/ejq_substack_articles/tree/main/secret-santa)** | 21 | 3.30.2 | ✅ 5/5 | [Article](https://www.the-main-thread.com/p/secret-santa-api-quarkus-java-tutorial) | ![secret-santa](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/secret-santa.json) |
| **[shapeshifter-api](https://github.com/myfear/ejq_substack_articles/tree/main/shapeshifter-api)** | 21 | 3.30.1 | ✅ 4/4 | [Article](https://www.the-main-thread.com/p/quarkus-zero-dto-polymorphic-api-tutorial) | ![shapeshifter-api](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/shapeshifter-api.json) |
| **stateless-api** | 21 | 3.29.4 | - | Article | ![stateless-api](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/stateless-api.json) |
| **[tech-store](https://github.com/myfear/ejq_substack_articles/tree/main/tech-store)** | 21 | 3.30.3 | ✅ 1/1 | [Article](https://www.the-main-thread.com/p/quarkus-playwright-end-to-end-browser-testing-java) | ![tech-store](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/tech-store.json) |
| **[tflite-agent-macos](https://github.com/myfear/ejq_substack_articles/tree/main/tflite-agent-macos)** | 25 | 3.30.3 | - | Article | ![tflite-agent-macos](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/tflite-agent-macos.json) |
| **timezone-storage-demo** | 21 | 3.29.4 | - | Article | ![timezone-storage-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/timezone-storage-demo.json) |
| **[toml-ai-config](https://github.com/myfear/ejq_substack_articles/tree/main/toml-ai-config)** | 21 | 3.30.3 | - | [Article](https://www.the-main-thread.com/p/toml-ai-configuration-quarkus-langchain4j-ollama) | ![toml-ai-config](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/toml-ai-config.json) |
| **url-shortener** | 21 | 3.23.3 | ✅ 3/3 | Article | ![url-shortener](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/url-shortener.json) |
| **[vaadin-task-manager](https://github.com/myfear/ejq_substack_articles/tree/main/vaadin-task-manager)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/vaadin-quarkus-java-ui-tutorial) | ![vaadin-task-manager](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/vaadin-task-manager.json) |
| **validator-demo** | 21 | 3.29.4 | ✅ 35/35 | Article | ![validator-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/validator-demo.json) |
| **[virtual-threads-demo](https://github.com/myfear/ejq_substack_articles/tree/main/virtual-threads-demo)** | 21 | 3.30.2 | - | Article | ![virtual-threads-demo](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/virtual-threads-demo.json) |
| **[voice-transcriber](https://github.com/myfear/ejq_substack_articles/tree/main/voice-transcriber)** | 25 | 3.30.3 | - | [Article](https://www.the-main-thread.com/p/java-speech-to-text-quarkus-whisper-ffm) | ![voice-transcriber](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/voice-transcriber.json) |
| **[wishlist-app](https://github.com/myfear/ejq_substack_articles/tree/main/wishlist-app)** | 21 | 3.30.1 | - | [Article](https://www.the-main-thread.com/p/quarkus-holiday-wishlist-tutorial-hibernate-soft-delete) | ![wishlist-app](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/wishlist-app.json) |
| **zombie-registry** | 21 | 3.29.4 | - | Article | ![zombie-registry](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/myfear/ejq_substack_articles/badges/zombie-registry.json) |

## 📚 Project Overview

Below are the example projects included in this repository, organized by topic. Each project folder is linked for easy access, and where available, a link to the corresponding Substack article is provided:

### 🧠 AI & LLM Integration
- [ai-document-assistant/](ai-document-assistant/): Document Q&A system with LangChain4j, Ollama, and pgvector for RAG capabilities.
- [ai-dungeon-master/](ai-dungeon-master/): Interactive text-based adventure game with AI dungeon master using LangChain4j and Ollama for dynamic storytelling.
- [ai-email-simulator/](ai-email-simulator/): Automating email generation and task extraction with LangChain4j and Ollama.  
  [Substack article](https://myfear.substack.com/p/quarkus-langchain4j-local-ai-task-extractor)
- [ai-error-handler-pii/](ai-error-handler-pii/): AI-powered exception handling, PII redaction, and user-friendly error messages.  
  [Substack article](https://myfear.substack.com/p/quarkus-ai-exception-handling-pii)
- [ai-memory/](ai-memory/): AI memory management and conversation context handling with LangChain4j.
- [ai-whitepaper-generator/](ai-whitepaper-generator/): AI-powered white paper generator using LangChain4j, Ollama, and iText for PDF generation.  
  [Substack article](https://myfear.substack.com/p/ai-whitepaper-generator-quarkus-langchain4j-itext)
- [captains-log-generator/](captains-log-generator/): Star Trek-style captain's log generator using AI with stardate calculation and mood-based entries.
- [credit-card-validator/](credit-card-validator/): AI-powered credit card validation using Luhn algorithm, brand detection, and LangChain4j chat interface.
- [dad-joke-generator/](dad-joke-generator/): AI-powered dad joke generator with LangChain4j and Ollama for guaranteed groans.
- [data-agent/](data-agent/): AI agent for CSV data analysis using tool-calling and local LLMs.  
  [Substack article](https://myfear.substack.com/p/ai-java-agent-quarkus-langchain4j-ollama)
- [dns-ai/](dns-ai/): AI-powered DNS lookup and analysis tool using LangChain4j with DNS record querying capabilities.
- [embedding-tutorial/](embedding-tutorial/): Text similarity and embeddings with LangChain4j and Ollama.  
  [Substack article](https://myfear.substack.com/p/java-quarkus-text-embeddings-similarity)
- [expense-splitter/](expense-splitter/): AI-powered expense splitting with receipt image processing using LangChain4j and Ollama.
- [flight-tracker-ollama/](flight-tracker-ollama/): AI-powered flight tracking with real-time aviation data and natural language queries.
- [gospel-in-code/](gospel-in-code/): Bible analysis application with semantic comparison, sentiment analysis, and vector embeddings.
- [intelligent-ticketing/](intelligent-ticketing/): AI-powered customer support system with ticket classification, knowledge base search, and automated processing using embeddings.
- [jvm-inspector-ai/](jvm-inspector-ai/): AI-powered JVM monitoring tool with thread analysis, deadlock detection, and intelligent diagnostics using LangChain4j.
- [llm-filter-demo/](llm-filter-demo/): Content moderation system using Bloom filters for fast pre-filtering and LLM for final content safety analysis.
- [llm-observability/](llm-observability/): LLM monitoring and observability tools for tracking AI model performance and usage.
- [quarkus-chain-of-thought/](quarkus-chain-of-thought/): AI reasoning application implementing structured chain-of-thought problem solving.
- [quarkus-chatbot/](quarkus-chatbot/): Real-time AI chatbot with LangChain4j and WebSocket.  
  [Substack article](https://myfear.substack.com/p/java-ai-chatbot-quarkus-langchain4j-websockets)
- [quarkus-image-describer/](quarkus-image-describer/): Describes images with a LangChain4j service.
  [Substack article](https://myfear.substack.com/p/quarkus-langchain4j-image-description-api)
- [quarkus-langchain4j-observability/](quarkus-langchain4j-observability/): Observability and monitoring for LangChain4j applications in Quarkus.
- [quarkus-meme-generator/](quarkus-meme-generator/): AI-powered meme generator using LangChain4j and image processing.
- [quarkus-supervisor-ai/](quarkus-supervisor-ai/): AI supervisor system with multiple specialized agents using Kafka messaging for distributed AI workflow orchestration.
- [semantic-llm-router/](semantic-llm-router/): Intelligent LLM request routing based on semantic analysis and model capabilities.
- [sentiment-analysis/](sentiment-analysis/): REST API for sentiment analysis with LangChain4j and Ollama.  
  [Substack article](https://myfear.substack.com/p/quarkus-dto-mapstruct-guide)
- [structured-ollama-tutorial/](structured-ollama-tutorial/): Structured data extraction with Ollama and LangChain4j.  
  [Substack article](https://myfear.substack.com/p/structured-data-llm-quarkus-langchain4j)
- [summarization-agent/](summarization-agent/): AI-powered text summarization agent with document processing capabilities.
- [text-analytics/](text-analytics/): Character interaction graph analysis for Huckleberry Finn using Quarkus, OpenNLP, and Ollama for sentiment analysis.  
  [Substack article](https://myfear.substack.com/p/text-analytics-quarkus-opennlp-huckleberry-finn)
- [grumbles-live/](grumbles-live/): Humorous AI news anchor built with LangChain4j.
  [Substack article](https://myfear.substack.com/p/quarkus-langchain4j-sarcastic-ai-news-anchor)
- [happy-place-app/](happy-place-app/): Sentiment-based content generator using local LLMs.
  [Substack article](https://myfear.substack.com/p/quarkus-ai-happy-feed-reactive-app)
- [openapi-ollama-doc-generator/](openapi-ollama-doc-generator/): Generate docs from OpenAPI using Ollama.
  [Substack article](https://myfear.substack.com/p/quarkus-openapi-ai-docs-langchain4j)
- [ai-design-critic/](ai-design-critic/): AI-powered design critique and feedback system.
  [Substack article](https://www.the-main-thread.com/p/langchain4j-learning-path-java-quarkus-ai)

### 📊 Data Processing & Integration
- [collaborative-editor/](collaborative-editor/): Real-time collaborative text editor using CRDT (Conflict-free Replicated Data Types) with WebSocket synchronization and AI writing assistance.
- [csv-uploader/](csv-uploader/): Dynamic CSV ingestion and schema creation in PostgreSQL.  
  [Substack article](https://myfear.substack.com/p/dynamic-csv-uploads-java-quarkus-postgresql)
- [file-upload-progress/](file-upload-progress/): Chunked file uploads with real-time progress tracking using Server-Sent Events (SSE).
- [panache-primevue-tutorial/](panache-primevue-tutorial/): Beautiful PrimeVue table backed by Quarkus and Panache with filterable, sortable Vue 3 frontend.  
  [Substack article](https://myfear.substack.com/p/quarkus-primevue-table-panache-tutorial)
- [quarkus-docling-converter/](quarkus-docling-converter/): Document conversion service using Docling library to convert various formats to text.
- [reactive-db-app/](reactive-db-app/): Reactive database operations and streaming with Quarkus and reactive programming patterns.
- [reactive-streaming-example/](reactive-streaming-example/): Reactive streams implementation with backpressure handling and event processing.
- [resource-reader/](resource-reader/): File resource handling, stream processing, and error handling.  
  [Substack article](https://myfear.substack.com/p/structured-data-llm-quarkus-langchain4j)
- [temporary-file-sharing/](temporary-file-sharing/): Secure temporary file sharing service with download limits and automatic cleanup using MinIO object storage.
- [qr-code-demo/](qr-code-demo/): QR code generation, image processing, and REST endpoints.  
  [Substack article](https://myfear.substack.com/p/qr-code-java-quarkus)
- [hibernate-search-orm-elasticsearch-quickstart/](hibernate-search-orm-elasticsearch-quickstart/): Hibernate Search quickstart with Elasticsearch.
  [Substack article](https://myfear.substack.com/p/hibernate-search-quarkus-elasticsearch-tutorial)
- [quarkus-hibernate-filters/](quarkus-hibernate-filters/): Query filtering using Hibernate ORM.
  [Substack article](https://myfear.substack.com/p/quarkus-hibernate-filters-soft-deletes)
- [color-palette-extractor/](color-palette-extractor/): Color palette extraction from images.
- [pdf-processing-pipeline/](pdf-processing-pipeline/): PDF processing and document analysis pipeline.
- [substack-discovery/](substack-discovery/): Substack content discovery and analysis tool.

### 🛡️ Security & Error Handling
- [api-key-manager/](api-key-manager/): Secret Agent themed API key management system with secure key generation, rotation, and usage tracking.
- [custom-error-pages-classic/](custom-error-pages-classic/): Custom error pages and JSON error responses with Qute and ExceptionMappers.  
  [Substack article](https://myfear.substack.com/p/quarkus-custom-error-pages-rest-qute)
- [jwt-case/](jwt-case/): JWT-based authentication and authorization.  
  [Substack article](https://myfear.substack.com/p/jwt-quarkus-murder-mystery)
- [secure-diary/](secure-diary/): Secure diary application with Bouncy Castle encryption, protecting thoughts one encrypted entry at a time.  
  [Substack article](https://myfear.substack.com/p/secure-diary-quarkus-bouncy-castle-java-tutorial)
- [security-jpa-quickstart/](security-jpa-quickstart/): JPA-based user authentication and PostgreSQL integration.  
  [Substack article](https://myfear.substack.com/p/jwt-quarkus-murder-mystery)
- [security-jpa-quickstart2/](security-jpa-quickstart2/): Alternative JPA-based authentication example.
- [self-learning-waf/](self-learning-waf/): Self-learning Web Application Firewall using DeepLearning4j for reactive Java security without static rules.  
  [Substack article](https://myfear.substack.com/p/self-learning-waf-quarkus-java-deeplearning4j)
- [totp-vault/](totp-vault/): TOTP and Vault-based secrets management.  
  [Substack article](https://myfear.substack.com/p/secure-java-api-totp-quarkus-vault)
- [zero-trust-uploads/](zero-trust-uploads/): Zero-trust file uploads with ClamAV antivirus scanning using secure in-memory pipeline before storage.  
  [Substack article](https://www.the-main-thread.com/p/zero-trust-file-uploads-quarkus-antivirus)
- [quarkflix-guards/](quarkflix-guards/): Hands on CDI Interceptors tutorial
  [Substack article](https://myfear.substack.com/p/quarkus-cdi-interceptors-real-world)
- [quarkus-response-tutorial/](quarkus-response-tutorial/): HTTP Response handling
  [Substack article](https://myfear.substack.com/p/quarkus-http-response-guide-java-developers)
- [quarkus-otp/](quarkus-otp/): TOTP (Time-based One-Time Password) implementation with Quarkus.
  [Substack article](https://www.the-main-thread.com/p/java-quarkus-totp-tan-security-tutorial)
- [secure-service/](secure-service/): Secure service implementation with authentication and authorization.
- [fraud-detector/](fraud-detector/): Fraud detection system with machine learning capabilities.

### 🏗️ Application Architecture & Patterns
- [breadcrumb-navigation/](breadcrumb-navigation/): Dynamic breadcrumb navigation component in Quarkus with zero-configuration auto-generation from URI paths.  
  [Substack article](https://myfear.substack.com/p/quarkus-qute-dynamic-breadcrumb)
- [composite-key-app/](composite-key-app/): Demonstrates composite keys with Hibernate Panache and student enrollment modeling.
- [flyway-adventure/](flyway-adventure/): Database migrations with Flyway.  
  [Substack article](https://myfear.substack.com/p/quarkus-flyway-database-migrations-java)
- [hll-tutorial/](hll-tutorial/): Scalable unique counting with HyperLogLog algorithm for counting millions of things with kilobytes of memory.  
  [Substack article](https://myfear.substack.com/p/quarkus-hyperloglog-unique-counting-java)
- [http-header-tutorial/](http-header-tutorial/): HTTP header handling tutorial with request/response manipulation and GZIP compression.
- [quarkus-dto-tutorial/](quarkus-dto-tutorial/): DTO mapping and transformation.  
  [Substack article](https://myfear.substack.com/p/quarkus-dto-mapstruct-guide)
- [quarkus-graphql/](quarkus-graphql/): Building GraphQL APIs in Quarkus.  
  [Substack article](https://myfear.substack.com/p/langchain4j-graphql-websocket-next)
- [quarkus-interceptor-tutorial/](quarkus-interceptor-tutorial/): Custom request interceptors, logging, and auditing.  
  [Substack article](https://myfear.substack.com/p/langchain4j-graphql-websocket-next)
- [quarkus-timezone-tutorial/](quarkus-timezone-tutorial/): Timezone handling best practices with Quarkus and Hibernate Panache for proper date management.  
  [Substack article](https://myfear.substack.com/p/quarkus-java-timezone-best-practices)
- [validation-example/](validation-example/): Form validation with Jakarta Validation and Qute.  
  [Substack article](https://myfear.substack.com/p/validation-java-quarkus)
- [i18n-demo/](i18n-demo/): Database-backed internationalization.  
  [Substack article](https://myfear.substack.com/p/java-quarkus-i18n-multilingual-app)
- [chirper/](chirper/): Simple microblogging demo.
  [Substack article](https://myfear.substack.com/p/build-twitter-clone-quarkus-kafka-qute)
- [credit-line-app/](credit-line-app/): Workflow example managing credit line approvals.
  [Substack article](https://myfear.substack.com/p/quarkus-credit-approval-state-machine)
- [greeting-operator/](greeting-operator/): Kubernetes operator for greeting resources.
  [Substack article](https://myfear.substack.com/p/java-kubernetes-operator-quarkus-guide)
- [mission-control/](mission-control/): Mission planning service with async tasks.
  [Substack article](https://myfear.substack.com/p/quarkus-ai-pii-redaction-dashboard)
- [multi-tenant-todo-app/](multi-tenant-todo-app/): Multi-tenant TODO API.
  [Substack article](https://myfear.substack.com/p/quarkus-multi-tenant-todo-java-hibernate)
- [quarkus-panache-transaction-tutorial/](quarkus-panache-transaction-tutorial/): Transaction patterns with Hibernate Panache.
  [Substack article](https://myfear.substack.com/p/quarkus-transactions-panache-guide?r=17bggb)
- [dynamic-agent-spawner/](dynamic-agent-spawner/): Dynamic agent spawning example.
  [Substack article](https://myfear.substack.com/p/agentic-java-multi-model-ai-quarkus)
- [dynamic-renderer/](dynamic-renderer/): Dynamic rendering service.
  [Substack article](https://myfear.substack.com/p/quarkus-langchain4j-ollama-two-step-ai-pipeline)
- [url-shortener/](url-shortener/): URL shortening service.
  [Substack article](https://myfear.substack.com/p/java-quarkus-url-shortener-tutorial)
- [wizard-app/](wizard-app/): Wizard-style application UI.
  [Substack article](https://myfear.substack.com/p/quarkus-multi-step-form-session-csrf)
- [a2a-demo/](a2a-demo/): Agent-to-Agent communication demonstration.
- [age-everywhere/](age-everywhere/): Age calculation and date handling service.
  [Substack article](https://www.the-main-thread.com/p/java-date-time-quarkus-birthday-api-tutorial)
- [approval-workflow/](approval-workflow/): Business process management and approval workflows.
- [archunit-bce/](archunit-bce/): Architecture testing with ArchUnit for business capability enforcement.
  [Substack article](https://www.the-main-thread.com/p/quarkus-archunit-java-bce-architecture-tutorial)
- [audit-app/](audit-app/): Application auditing and monitoring system.
  [Substack article](https://www.the-main-thread.com/p/quarkus-business-score-java-tutorial-detect-zombie-apps)
- [banner-studio/](banner-studio/): ASCII banner generation and styling tool.
  [Substack article](https://www.the-main-thread.com/p/quarkus-ascii-banner-studio-qute-figlet)
- [car-filter-app/](car-filter-app/): Car filtering and search application.
- [cdi-events-demo/](cdi-events-demo/): CDI events and observer pattern demonstration.
- [coffee-api/](coffee-api/): Coffee shop API with OpenAPI documentation.
  [Substack article](https://www.the-main-thread.com/p/quarkus-openapi-java-coffee-api-tutorial)
- [community-app/](community-app/): Community management application.
  [Substack article](https://www.the-main-thread.com/p/remote-office-work-from-home-guide)
- [fleet-insure/](fleet-insure/): Fleet insurance management system.
- [granular-rbac-tutorial/](granular-rbac-tutorial/): Granular Role-Based Access Control implementation.
- [greet-hypermedia/](greet-hypermedia/): Hypermedia API implementation with HATEOAS.
  [Substack article](https://www.the-main-thread.com/p/spring-hateoas-to-quarkus-hypermedia-migration)
- [meme-service/](meme-service/): Meme generation and management service.
  [Substack article](https://www.the-main-thread.com/p/quarkus-json-jackson-langchain4j-meme-service)
- [museum/](museum/): Museum management and exhibition system.
- [negotiation-simulator/](negotiation-simulator/): Business negotiation simulation system.
- [order-service/](order-service/): Order processing and management service.
- [poll-doodle/](poll-doodle/): Polling and scheduling application.
  [Substack article](https://www.the-main-thread.com/p/quarkus-java-doodle-group-poll-tutorial)
- [property-testing/](property-testing/): Property-based testing with Jqwik.
- [qualifiers-lab/](qualifiers-lab/): CDI qualifiers and dependency injection lab.
- [quantum-identicons/](quantum-identicons/): Quantum-inspired identicon generation.
- [quarkus-agentic/](quarkus-agentic/): Agentic AI system implementation.
- [quarkus-ai-debugger/](quarkus-ai-debugger/): AI-powered debugging assistant.
- [quarkus-api-testing/](quarkus-api-testing/): API testing framework and examples.
  [Substack article](https://www.the-main-thread.com/p/quarkus-rest-api-testing-vs-spring-mockmvc)
- [quarkus-coverage-tutorial/](quarkus-coverage-tutorial/): Code coverage analysis and reporting.
- [quarkus-guardrails/](quarkus-guardrails/): AI guardrails and safety measures.
- [quarkus-ldap-demo/](quarkus-ldap-demo/): LDAP authentication integration.
  [Substack article](https://www.the-main-thread.com/p/quarkus-ldap-authentication-tutorial)
- [quarkus-mcp/](quarkus-mcp/): Model Context Protocol implementation.
  [Substack article](https://www.the-main-thread.com/p/java-quarkus-langchain4j-ollama-mcp-tutorial)
- [quarkus-mutation-demo/](quarkus-mutation-demo/): Mutation testing demonstration.
- [quarkus-read-replica/](quarkus-read-replica/): Database read replica configuration.
- [quarkus-roq-tutorial/](quarkus-roq-tutorial/): Roq framework tutorial and examples.
- [quarkus-soap-multi/](quarkus-soap-multi/): Multi-protocol SOAP service implementation.
- [quarkus-todo-app/](quarkus-todo-app/): Todo application with CRUD operations.
- [quarkus-versioning-tutorial/](quarkus-versioning-tutorial/): API versioning strategies and implementation.
- [quarky-cart/](quarky-cart/): Shopping cart implementation.
- [renarde-tasks/](renarde-tasks/): Task management with Renarde framework.
  [Substack article](https://www.the-main-thread.com/p/quarkus-renarde-full-stack-java-web-tutorial)
- [resilient-ai/](resilient-ai/): AI resilience and fault tolerance patterns.
  [Substack article](https://www.the-main-thread.com/p/quarkus-fault-tolerance-langchain4j-ai-resilience)
- [rest-deprecation-practice/](rest-deprecation-practice/): REST API deprecation strategies.
- [rest-testing-demo/](rest-testing-demo/): REST API testing with RestAssured and Pact.
  [Substack article](https://www.the-main-thread.com/p/quarkus-api-testing-restassured-pact-jqwik)
- [roq-author-website/](roq-author-website/): Author website built with Roq framework.
- [unicode-greetings/](unicode-greetings/): Unicode and internationalization examples.
- [very-simple-app/](very-simple-app/): Minimal Quarkus application example.
  [Substack article](https://www.the-main-thread.com/p/proof-of-concept-java-quarkus-guide)
- [xa-transaction-tutorial/](xa-transaction-tutorial/): XA transaction management tutorial.
- [year-end-invoices/](year-end-invoices/): Year-end invoice processing system.

### 🛠️ Utilities, Monitoring & Misc
- [error-handling-app/](error-handling-app/): RFC 7807 standardized error handling in Quarkus for secure, standards-based API error responses.  
  [Substack article](https://myfear.substack.com/p/quarkus-rfc7807-error-handling-java)
- [geonames-search/](geonames-search/): High-performance autocomplete search with Quarkus, Panache, and PostgreSQL for geographic locations.  
  [Substack article](https://myfear.substack.com/p/high-performance-autocomplete-search-quarkus-java)
- [health-checker/](health-checker/): Website health monitoring service using MicroProfile Health, YAML configuration, and HttpClient for uptime checking.  
  [Substack article](https://myfear.substack.com/p/quarkus-website-health-check-yaml)
- [household-chore-assignment/](household-chore-assignment/): Fair household chore assignment using the Gale-Shapley algorithm for stable matching.  
  [Substack article](https://myfear.substack.com/p/fair-chore-assignment-java-quarkus-gale-shapley)
- [quarkus-sftp-compose/](quarkus-sftp-compose/): Smart SFTP file upload system with PostgreSQL metadata storage using Quarkus Dev Services.  
  [Substack article](https://myfear.substack.com/p/quarkus-sftp-postgresql-file-upload-tutorial)
- [realtime-monitor/](realtime-monitor/): JVM heap memory monitoring and dashboard UI.  
  [Substack article](https://myfear.substack.com/p/quarkus-dev-services-continuous-testing)
- [quote-cli/](quote-cli/): CLI tool for quotes or text processing.  
  [Substack article](https://myfear.substack.com/p/quarkus-native-cli-java-quotes)
- [cloud-metrics/](cloud-metrics/): Tenant-aware metrics and rate limiting demo.
- [matrix-test/](matrix-test/): Simple Quarkus demo inspired by The Matrix.
- [quarkus-coverage-tutorial/](quarkus-coverage-tutorial/): Jacoco code coverage setup.
- [quarkus-otel-adventure/](quarkus-otel-adventure/): OpenTelemetry observability and distributed tracing implementation with Quarkus microservices.
- [quarkus-task-runner/](quarkus-task-runner/): Background task execution and scheduling with Quarkus and job processing patterns.
- [quarkus-unleash-tutorial/](quarkus-unleash-tutorial/): Feature flags and toggles implementation using Unleash with Quarkus for controlled feature rollouts.
- [api-perf-resilience/](api-perf-resilience/): API performance and resilience patterns.
  [Substack article](https://www.the-main-thread.com/p/quarkus-api-performance-caching-rate-limiting-fault-tolerance)
- [bsky-javafeed-generator/](bsky-javafeed-generator/): Bluesky Java feed generator.
- [bsky-javafeed-generator-reactive/](bsky-javafeed-generator-reactive/): Reactive Bluesky Java feed generator.
- [caching-tutorial/](caching-tutorial/): Caching strategies and implementation.
- [camel-rest-sql/](camel-rest-sql/): Apache Camel REST SQL integration.
- [camel-rss-quarkus/](camel-rss-quarkus/): Apache Camel RSS integration with Quarkus.
- [log-to-obs/](log-to-obs/): Logging to observability platforms.
- [mutiny-test/](mutiny-test/): Mutiny reactive programming testing.

## 🚧 Work in Progress

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