React client
Captures customer text and displays the category with a visual confidence score.
AI engineering case study
Every message,
understood.
A full-stack classification service that turns unstructured customer text into a reliable category and confidence score through a clean REST API.
4CategoriesRESTIntegration0-1Confidence3/3Tests passing
01 / The challenge
Customer messages arrive without structure.
Support teams receive complaints, questions, feedback and unrelated messages in the same stream. Manual triage slows response time and creates inconsistent routing. This project provides a small, integration-ready service that applies one shared classification policy to every message.
02 / Architecture
A focused path from input to insight.
Express API
Validates requests and exposes a focused POST /api/classify endpoint.
Ollama model
Uses llama3.2:3b with a deterministic prompt and strict JSON output.
MongoDB
Optionally stores successful classifications through Mongoose.
POST /api/classifyJSON
{
"text": "My order arrived damaged."
}
{
"category": "Complaint",
"confidence": 0.96
}03 / API design
One endpoint.
Predictable output.
The API accepts a text string, validates it, invokes the model service and normalizes the response. Consumers always receive an allowed category and a confidence value between zero and one.
Check API health04 / Engineering decisions
AI output treated as untrusted input.
Allow-listed categories
Model output is matched case-insensitively against Complaint, Query, Feedback and Other.
Bounded confidence
Numeric confidence is clamped to the valid 0-1 range, with a documented fallback.
Defensive validation
Empty text and payloads over 5,000 characters return clear HTTP 400 responses.
Optional persistence
The classifier remains available when MongoDB is not configured or connected.
05 / Technology
ReactViteNode.jsExpressMongoDBMongooseOllamaLangChainVercelCloudflare Tunnel
06 / Delivered
Built, tested and documented.
Responsive React testing interface
Layered controller, route and service structure
Automated API and normalization tests
Postman collection and environment examples
Vercel serverless deployment configuration
Detailed local and production setup guide
Explore the working product