FetchXML Builder
is the freeware and open source (hosted on GitHub) tool you should check out.
The encouraging product tagline is "Build queries for Microsoft Dataverse, Dynamics 365 and the Power Platform. Investigate data. Get code. Empower yourself to achieve more."
It and its developer, Jonas Rapp, have a long history with MSFT cloud. Jonas explains: "The Power Platform uses FetchXML internally to query the Common Data Service (CDS) for information."
He adds:
FetchXML is the proprietary query language of Microsoft Dynamics CRM.
Which has been renamed to Microsoft Dynamics 365 Customer Engagement.
Which has transformed into the Common Data Service for the Power Platform.
Through all these transitions, FetchXML has persisted as the go-to query language for the platform.
SQL
FetchXML can be explained as the “select equivalent of SQL”. Granted, SQL is a much more colorful querying language, with full CRUD capabilities as well as functions, stored procedures etc. FetchXML does not compare to SQL in that way.
But it reads data from the Common Data Service natively. And it does it well.