---
title: "Introducing NCrontab Tester (Blazor WebAssembly)"
excerpt: "Introducing NCrontab Expression tester, made using NCrontab .NET library, Blazor WebAssembly, and hosted on Azure Static Web Apps"
publishDate: "2020-08-05T00:00:00"
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Web Assembly (WASM) has allowed many different programming platforms to now be supported inside of the web browser. With <a rel="noopener" href="https://devblogs.microsoft.com/aspnet/blazor-webassembly-3-2-0-now-available/" target="_blank">Blazor WebAssembly</a>, we can now develop C# .NET applications that run inside of the browser sandbox.





This also means that many .NET libraries can be used within the same context, such as <a href="https://github.com/atifaziz/NCrontab">NCrontab</a>. This library provides crontab parsing, crontab formatting and the DateTime calculation of occurrences based on a crontab expression. As opposed to the five-part format for classic CRON expressions, NCrontab support a six-part format that allows for seconds to be configured as well. The six-part NCrontab syntax is mandatory for Azure services such as <a href="https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-timer?tabs=csharp#ncrontab-expressions" class="alert-link">Timer Triggered Azure Functions</a> and <a href="https://docs.microsoft.com/en-us/azure/app-service/webjobs-create#ncrontab-expressions" class="alert-link">scheduled Azure WebJobs.</a>





There are many CRON Expression tools on the web. I chose to create another CRON Expression tool because of these reasons:





- NCrontabs syntax is slightly different than classic CRON expressions when using the six-part format required for Azure.
- NCrontab is a popular library for .NET CRON parsing. It's used by Azure services and Hangfire.
- It seemed like a fun exercise to get familiar with the new Blazor WebAssembly framework





To make this little exercise even more interesting for myself, I am using the new Azure Static Web Apps (in preview) service to host the Blazor WebAssembly application as a static web application.





Follow this link to give the tool a try:




<p style="text-align: center;"><a href="https://ncrontab.swimburger.net/" class="btn">NCrontab Expression Tester</a></p>



<p style="text-align: left;">Follow this link to check out the source code:</p>



<p style="text-align: center;"><a href="https://github.com/Swimburger/NCrontabTester" class="btn">GitHub Repository</a></p>