Price tracker with a polite scraper

Track the price of a few products on a site that allows scraping and get a message when one drops.

Why build it

You learn HTTP, HTML parsing and scheduling, plus the habits that keep a scraper legal and polite: robots.txt, rate limits and caching.

Features

• Add a product URL and target price
• Fetch and parse the current price
• Store price history in SQLite
• Alert by email or Telegram when below target
• Price history chart

Roadmap

1. p1

   Choose a source

   • Pick a site whose terms and robots.txt allow it
   • Check for an official API first
   • Save sample HTML for tests
2. p2

   Parse and store

   • Fetch with requests and a custom User-Agent
   • Parse the price with BeautifulSoup
   • Insert into SQLite with a timestamp
3. p3

   Schedule and alert

   • Run on a schedule with cron or GitHub Actions
   • Send the alert
   • Back off on errors
4. p4

   Show history

   • Generate a chart with matplotlib
   • Document how to add a new site parser

Common pitfalls

• Hammering a site with requests
• Parsing with brittle selectors and no tests against saved HTML

Skills you will practise

• HTTP
• HTML parsing
• SQLite
• Scheduling