Quartz.NET vs Windows Scheduled Tasks. How different are they?

With Quartz.NET I could contrast some of the earlier points:

1. Code to write - You can express your intent in .NET language, write unit tests and debug the logic
2. Integration with event log, you have Common.Logging that allows to write even to db..
3. Robust and reliable too
4. Even richer API

It's mostly a question about what you need. Windows Scheduled tasks might give you all you need. But if you need clustering (distributed workers), fine-grained control over triggering or misfire handling rules, you might like to check what Quartz.NET has to offer on these areas.

Take the simplest that fills your requirements, but abstract enough to allow change.

My gut reaction would be to try and get the integral WinScheduler to work with your needs first before installing yet another scheduler - reasoning:

1. no installation required - installed and enabled by default
2. no code to write - jobs expressed as metadata
3. integration with event log etc.
4. robust and reliable - good enough for MSFT, Google etc.
5. reasonably rich API - create jobs, check status etc.
6. integrated with remote management tools
7. security integration - run jobs in different credentials
8. monitoring tooling

Then reach for Quartz if it doesn't meet your needs. Quartz certainly has many of these features too, but resist adding yet another service to own and manage if you can.

One important distinction, for me, that is not included in the other answers is what gets executed by the scheduler.

Windows Task Scheduler can only run executable programs and scripts. The code written for use within Quartz can directly interact with your project's .NET components.

With Task Scheduler, you'll have to write a shell executable or script. Inside of that shell, you can interact with your project's components. While writing this shell code is not a difficult process, you do have to consider deploying the extra files.

If you anticipate adding more scheduled tasks over the lifetime of the project, you may end up needing to create additional executable shells or script files, which requires updates to the deployment process. With Quartz, you don't need these files, which reduces the total effort needed to create and deploy additional tasks.