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Diving deeper: using cURL requests in alert statements

Use a public request captured in Chrome DevTools when the price, availability, or information you need is loaded by an API rather than visible in the page HTML.

Sometimes the price, stock level, or availability you see in a browser is not in the page itself. The site loads it afterwards from an API. In those cases, a cURL command gives AlertChecker the same public request your browser used, including its method, headers, and request body.

A concrete use case: hotel room prices

A hotel search can load room prices after you choose the hotel, dates, and guests. One useful alert statement is: “The nightly GBP price for the Family Experience package at Park Plaza Leeds has changed for any of these nights: 26–27 August, 27–28 August, or 28–29 August.” Put the cURL request that returned those room prices beneath that sentence.

The statement tells AlertChecker what to evaluate; the command tells it where the current room data comes from. This same approach works for a Tenerife holiday price, a CeX stock check, or another site whose useful data arrives through a public request.

Find the request in Chrome

  1. Open the page that shows the current price or availability.
  2. Open Chrome DevTools, choose the Network panel, and clear the existing requests.
  3. Repeat the action that loads the information, such as selecting the room or changing the dates.
  4. Press ⌘F on macOS or Ctrl F on Windows and Linux. Search for a distinctive value from the result, such as the current room price, hotel code, product name, or availability wording.
  5. Choose a matching request and check its Response tab contains the data you care about.
  6. Right-click that request, then choose Copy and Copy as cURL.

Put it into the alert

Write the condition first, add a blank line, then paste the copied cURL command. Keep the request together: for API requests, the URL alone often is not enough. A POST request may need its JSON body, and the server may need a content-type header to understand it.

The nightly GBP price for the Family Experience package at Park Plaza Leeds has changed.

curl 'https://www.radissonhotels.com/availability-api/stays-by-rooms' \
  -H 'content-type: application/json' \
  --data-raw '{"hotelCode":"GBPPLBAPPL","checkInDate":"2027-08-25","checkOutDate":"2027-08-31"}'

Trim carefully and keep secrets out

Start by testing the copied command as-is. If it works and it is too long, remove one non-essential browser header at a time and test again. Keep the URL, HTTP method, JSON body, and any header that the response truly needs. Do not remove several things together, or you will not know which change broke the request.

Do not paste personal cookies, Authorization headers, API keys, signed URLs, CSRF values, or account details into an alert. They can expire, expose access to your account, and make the alert unreliable. Look instead for a public request that returns the same price or availability. If the data only appears after signing in, it is not a good candidate for a cURL-based alert.

Chrome documents the Network panel's search and Copy as cURL features in its Network features reference. Test the statement before relying on it.