Just found this utility website — endoflife.date — which shows the schedule for when the software you use will no longer be supported. It displays the information in a nice color-coated table. There are multiple categories of software available.
As an example, here's the chart for PHP
We need more web apps like this:
* The website does one thing very well.
* The domain name tells you what it does.
* Clean URLs
* Light JS and CSS usage