Competitor Pricing Change Monitor

Overview

Competitor Pricing Change Monitor is an Apify actor that continuously monitors product or pricing pages and emits events only when a meaningful price change occurs.

It is designed to be:

• Cost-efficient

• Memory-safe under Apify limits

• Production-ready

• Reusable across multiple websites

This actor is ideal for teams that need reliable competitor pricing intelligence without noisy data or high operational cost.

What Problem This Actor Solves

Teams frequently need to:

• Track competitor price changes

• Detect increases or discounts quickly

• Avoid manually checking websites

• Prevent false alerts from unchanged prices

Most scraping solutions either:

• Store full HTML snapshots

• Emit data on every run

• Consume unnecessary storage and RAM

This actor solves the problem by tracking only what matters.

How It Works (Architecture)

For each monitored item:

• Fetches the page using lightweight HTTP requests (no browser)

• Extracts the price using a user-provided CSS selector

• Normalizes the price into a numeric value

• Reads the last known price from Apify’s Key-Value Store

• Compares old vs new price in memory

• Overwrites the stored price

• Emits a dataset record only if a meaningful event occurs

Change Types Emitted

• first_seen
• increase
• decrease
• price_not_found

Events with no_change are intentionally not written to the dataset.

Storage & Cost Model (Important)

Key-Value Store (State)

• Stores only the latest price per URL

• One key per monitored item

• Constant size (does not grow over time)

Dataset (Events)

• Append-only

• Stores only meaningful changes

• No data written when prices remain unchanged

Input Format

{
  "items": [
    {
      "url": "https://books.toscrape.com/catalogue/a-light-in-the-attic_1000/index.html",
      "priceSelector": ".price_color"
    }
  ]
}
Output Format (Dataset):
{
  "url": "https://books.toscrape.com/catalogue/a-light-in-the-attic_1000/index.html",
  "oldPrice": 51.77,
  "newPrice": 45.00,
  "changeType": "decrease"
}