Instrumenting My MERN E-Commerce Application with SigNoz: From Zero to Full Observability

Modern applications don't just need features—they need observability . When an API becomes slow, a database query takes too long, or an unexpected error occurs, developers need answers quickly. That's where SigNoz and OpenTelemetry come in. For the Agents of SigNoz Hackathon 2026 , I integrated SigNoz into my existing MERN Stack e-commerce application called Ram Store and transformed it into a fully observable application. In this blog, I'll walk through what I built, how I instrumented it, the challenges I faced, and what I learned. About the Project Ram Store is a full-stack e-commerce platform built using the MERN Stack. Features User Authentication Product Management Categories & Subcategories Shopping Cart Address Management Order Management MongoDB Database Tech Stack React (Vite) Node.js Express.js MongoDB Docker OpenTelemetry SigNoz Winston Logger Why Observability? Before integrating SigNoz, I could only rely on: console.log() Manual debugging Browser Network tab When something failed, I had questions like: Which API is slow? Why is the response delayed? Which MongoDB query is taking time? How many requests is my backend serving? Where exactly did the error happen? Without observability, finding answers takes time. I wanted a single place where I could monitor everything. That's why I chose SigNoz . Setting Up SigNoz I self-hosted SigNoz locally using Docker. Once all the containers were running successfully, the dashboard became available. After the initial setup, the next step was instrumenting my backend. Integrating OpenTelemetry I added OpenTelemetry to my Node.js backend. Using the Node SDK together with automatic instrumentation, I configured: Express instrumentation HTTP instrumentation MongoDB instrumentation OTLP gRPC exporter Now every request automatically generates telemetry without modifying every route. Distributed Traces One of my favorite features is Distributed Tracing . Whenever I perform an action in Ram Store—like opening products or ad