Your task
All challenges
Challenge 26
Uptime Alerts That Don't Cry Wolf
Check your sites every five minutes and get one message when a site goes down and one when it comes back – never the same warning again and again.
Your bonus task
Warn us three weeks before a site's security certificate expires, so it never lapses unnoticed.
Example use cases
- A small team running three sites with no budget for a monitoring service.
- An agency that wants to notice a client's site is down before the client phones.
- Any check where only the moment of change matters – a price crossing a threshold, a queue filling up, a door left open.
Before you start
- 01
Sign up for n8n Cloud or open your n8n workspace. No other account is needed.
- 02
Create a Data Table called site-status with two columns: url as text and up as a boolean. This is where the workflow remembers what it saw last time.
- 03
Test with endpoints built for it: https://httpbin.org/status/200 always answers 200 and https://the-internet.herokuapp.com/status_codes/500 always answers 500, so you can watch both paths without taking anything down.
- 04
To receive the message, use ntfy.sh: pick a hard-to-guess topic name and open https://ntfy.sh/your-topic in a browser or install the ntfy app. No account is needed.
- 05
For the bonus, certificate history comes from crt.sh, which is public, free and slow – it often takes half a minute to answer.
Nodes you'll use
What the workflow must do
- 01
A site that answers 500 produces exactly one alert, and running the workflow again five minutes later while it is still broken produces none.
- 02
When that site starts answering normally again, one "back up" message arrives, and the stored stateWhat the workflow remembers between runs. Without it, every check looks like the first one and the alert repeats forever. matches what was last seen for every site.
- 03
The first ever run sends nothing at all, even though nothing is stored yet, and a site that times out is treated as down rather than crashing the run. Bonus: a certificate with 21 days or fewer left produces a warning naming the expiry date.
Tip
Need a tip?
Reveal up to five tips, one at a time.
Still stuck? Ask on the n8n community forum
Solution
See the workflow challenge answer
Reveal the completed workflow only when you are ready to compare it with your own.
Submit as solved
Ready to submit?
Submit when your team has a working workflow to demonstrate.