Hexabot — Open-Source Chatbot Builder

The Problem

Businesses need chatbots for customer support, but most solutions are either too expensive (Dialogflow, Botpress Cloud) or too complex to set up (self-hosted alternatives). There was a gap for an open-source, easy-to-deploy chatbot builder.

The Solution

Hexabot is an open-source chatbot builder that lets non-technical users create conversational flows using a visual editor. It supports multi-channel deployment (web, WhatsApp, Messenger) and is fully self-hostable.

What I Built

Zookeeper-Based Leader Election

As Hexabot scaled horizontally, we needed to ensure cron jobs (message cleanup, analytics, session expiry) only ran on one instance. I designed a leader election mechanism using Apache Zookeeper that safely coordinates distributed cron execution.

Chat Flow Engine

Developed the core chat flow engine that serves 500+ daily active users. The engine processes user messages through decision trees, handles context management, and supports rich message types (buttons, carousels, quick replies).

Docker Optimization

Optimized Docker builds using multi-stage builds and layer caching, reducing CI/CD pipeline time by 53%. This directly improved developer velocity — PRs went from 8+ minutes to under 4 minutes for the build step.

Impact

• 700+ GitHub stars — active and growing open-source community
• Adopted by major Tunisian telecom providers for customer support
• 500+ daily active users across deployed instances
• 53% CI/CD time reduction through Docker optimization

Tech Stack

• Frontend: Next.js, TypeScript
• Backend: NestJS, MongoDB
• Infrastructure: Docker, Redis, Zookeeper
• CI/CD: GitHub Actions