FX Monitor

Real-time currency exchange rate monitor with browser push notifications.

Why

There are many FX monitoring tools out there, but most require a phone app, email subscriptions, or third-party services that handle your data. This project is built for self-hosting — your subscription data stays on your own server.

More importantly, many office workers can't check their phones during work hours, and logging into external websites may be against company policy. Browser Web Push works differently: notifications are delivered directly by the browser in the background, no app or email needed. You get alerted the moment a rate target is hit, right on your work computer, without opening anything.

Features

• Live FX rate charts (Frankfurter, Yahoo Finance)
• Price alerts via Web Push (Chrome, Firefox, Safari)
• Each alert notifies once; user can reactivate from the My Alerts panel
• Rate limiting and input validation

Configuration

All configuration is via environment variables. Copy .env.example to .env and fill in:

Variable	Description	Default
VAPID_PRIVATE_KEY_PATH	Path to VAPID private key PEM file	vapid_private.pem
VAPID_PUBLIC_KEY	VAPID public key (base64url)	—
VAPID_EMAIL	Contact email for push service	mailto:admin@example.com
POLL_INTERVAL	Alert check interval in seconds	60
DB_PATH	SQLite database file path	fx_monitor.db

Generate VAPID keys

pip install pywebpush
python3 -c "
from py_vapid import Vapid
import base64
v = Vapid()
v.generate_keys()
pub = base64.urlsafe_b64encode(v.public_key.public_bytes(
    __import__('cryptography.hazmat.primitives.serialization', fromlist=['Encoding']).Encoding.X962,
    __import__('cryptography.hazmat.primitives.serialization', fromlist=['PublicFormat']).PublicFormat.UncompressedPoint
)).decode().rstrip('=')
v.save_key('vapid_private.pem')
print('VAPID_PUBLIC_KEY=' + pub)
"

Run with Docker

# 1. Create data directory
mkdir -p data

# 2. Copy and fill in config
cp .env.example .env

# 3. Build and start
docker compose up -d

Data is persisted in ./data/ and the VAPID key is mounted read-only from ./vapid_private.pem.

Run locally

mkdir -p data
pip install -r requirements.txt
uvicorn main:app --host 0.0.0.0 --port 8000

Contributing

To add a new data source, create sources/your_source.py:

from sources.base import RateSource

class YourSource(RateSource):
    name = "Your Source"

    async def get_currencies(self) -> list[dict]: ...
    async def get_rate(self, base, quote) -> float: ...
    async def get_history(self, base, quote, start, end, interval="1d") -> list[dict]: ...

It will be auto-discovered and appear in the UI dropdown.