crontab guru is described as 'An easy to use editor for crontab schedules'. There are more than 10 alternatives to crontab guru for a variety of platforms, including Online / Web-based, Google Chrome, Firefox, Mac and Windows. The best alternative is crontab, which is both free and Open Source. Other great apps like crontab guru are EasyCron (Freemium), Cron As A Service (Paid), Looper (Paid) and YouXube - Repeat Youtube Videos (Free).
The Posthook API enables application developers to start scheduling tasks in minutes. Schedule one-off tasks for tomorrow or the first of next month by making a request to the API and setting up a webhook to process these tasks.
WebGazer is a website and cron monitoring service. We check if your website and REST APIs are up, and notify you if anything goes wrong. You could also send periodic HTTP requests at the end of cron jobs or scheduled tasks to monitor.