I Built a Self-Hosted AI Support Widget with Spring Boot (No Monthly SaaS Fees)

Every new SaaS seems to embed ChatGPT these days. Most AI support solutions rely on third-party platforms, monthly subscriptions, and vendor lock-in. While they're great products, I wanted something different. I wanted complete ownership. I wanted to deploy everything on my own server, use my own OpenAI API key, customize every part of the experience, and embed the widget into any website with a single script tag. So I built my own self-hosted AI support widget using Spring Boot and Vanilla JavaScript. Why I Built It When building small products and websites, I realized that customer support quickly becomes a problem. Users have questions about pricing, features, returns, or simply get stuck. Most developers solve this by integrating services like Intercom, Crisp, or Tidio. Those platforms are excellent, but they also mean: Monthly subscription costs Vendor lock-in Customer conversations stored on third-party platforms Limited customization Another external dependency I wanted something that developers could completely own. The Goal The goal was simple. Build an AI-powered customer support widget that developers can deploy on their own server and integrate into any website in less than a minute. The widget should: Answer customer questions using AI Learn from a custom knowledge base Match the company's branding Store conversation history Allow human handoff Be easy to deploy Require only one script tag to embed Technology Stack Java 17 Spring Boot 3 Spring Security Spring Data JPA Thymeleaf Vanilla JavaScript H2 Database (MySQL supported) OpenAI API Architecture The overall architecture is intentionally simple. Visitor │ ▼ AI Chat Widget (Vanilla JavaScript) │ ▼ Spring Boot REST API │ ▼ OpenAI API │ ▼ Database (H2 / MySQL) Keeping the frontend framework-free makes the widget lightweight and easy to embed into virtually any website. One-Line Integration Adding the widget to a website only requires a single script. <script src="/widget/widget.js" data-api-base=""></sc