Outliers Analytics
A full-stack BI dashboard over six independent business datasets — Sales & E-commerce, Customers, Marketing, Inventory, Banking & Financial, and HR — built with Next.js, DuckDB, and Recharts. Every metric is computed server-side from the source CSVs; nothing is hardcoded on the frontend.
Live demo: https://analytics-dashboard-phi-kohl.vercel.app
Case study: docs/CASE_STUDY.md — overview, architecture, key decisions, and screenshots
Architecture
CSV files → Ingestion/validation → DuckDB (in-memory) → SQL aggregation → API routes → React UI
- Next.js 16 (App Router) + TypeScript — pages under
src/app/, API routes under src/app/api/.
- DuckDB (
@duckdb/node-api) — all analytical queries run in SQL against an in-memory DuckDB instance loaded from the CSVs at startup.
- Recharts + shadcn/ui (base-ui) + Tailwind CSS v4 — charts and components, themed via CSS variables.
- Automatic refresh — a manual "Refresh Data" button plus a 30s poll detect source-file changes (mtime/size) and re-ingest only when something actually changed.
No cross-dataset joins
Three datasets share a Customer_ID-shaped column and two share a Product_ID-shaped column, which looks like a foreign-key relationship. It isn't: joining on Customer_ID and comparing Age agrees only 1.5–1.7% of the time across every pair (random-chance level), and joining on Product_ID and comparing Category mismatches 89% of the time. These are independently-generated synthetic ID pools that happen to share a numeric range and string format.
Every page in this app is built on exactly one dataset. The Data Explorer documents this naming coincidence as a relationship diagram, explicitly labeled as unverified — see docs/adr/0001-no-cross-dataset-joins.md for the full write-up and match-rate evidence.
Pages
| Page | Source dataset |
|---|
| Executive Overview | all six, reported per-domain (no blended metrics) |
| Sales & E-commerce | sales_ecommerce_data |
| Customers | customer_demographics_data |
| Marketing | marketing_campaigns_data |
| Inventory | product_inventory_data |
| Banking & Financial | banking_financial_data |
| HR / Employees | employee_hr_data |
| Data Explorer | all six, browsed independently — search, filter, sort, paginate, export CSV |
Screenshots
Executive Overview
Sales & E-commerce
Customers
Marketing
Inventory
Banking & Financial
HR / Employees
Data Explorer
Getting started
npm install
npm run dev
Open http://localhost:3000. The six source CSVs in the project root are ingested into DuckDB automatically on first request.
npm run lint # ESLint
npm run build # production build
Project docs
