Real-Time FX Rate Tracker & Alerts

An any-to-any foreign-exchange tracker with live reference rates, historical charts, and a server-side alert engine that fires 24/7 by email and browser push — no open tab required.

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Overview

Built end-to-end for an indie product founder who wanted a clean, self-owned FX rate tracker. Users pick any base currency, watch live cross-rates on a card grid, and chart history across ranges from 1 hour to multi-year.

The standout is the alerting: users set threshold rules and the server evaluates them on a schedule, firing notifications even when nobody has the app open. The whole stack was deployed and fully handed over onto the client's own infrastructure.

Key Features

Any-to-any cross rates derived from a free reference feed
Add any ISO currency to the grid on the fly
Historical charts (1H → All) with Chart.js
Server-side alert engine — fires 24/7, no tab needed
Email + browser Web Push notifications
Google sign-in via Auth0
Cron-driven rate polling into a local store
Mobile-first responsive dark UI

Tech Stack

Node.js / Express better-sqlite3 node-cron Auth0 (OpenID Connect) Chart.js Web Push (VAPID) Nodemailer Render CI deploy + handover

Outcome

Delivered in full and migrated onto the client's own hosting, repo and accounts — nothing left tied to us. The client called it "a very good job" and moved straight to final payment.