As a Dynamics 365 CRM developer, you will want to get the Level Up for Dynamics 365/Power Apps browser extension by Natraj Yegnaraman.
The extension is available for multible browsers, including:
Microsoft Edge – Chrome – Firefox
Let me demonstrate what it looks like in Edge. Click the extension icon in the browser. That will open the extension in a pop-up Express Mode:

To open the standard Sidebar, which I prefer to work with, you scroll down to the bottom of the popup and click “default”:

That opens the full extension in a sidebar window:

The extension contains A LOT of invaluable features. Let me just briefly mention some of my favourites:
On screen display of form field names and one-click copy to clipboard function

If you can’t remember exactly what a field is called in the database, you can use the “Logical Names” feature to show the field names directly in the form. If you click the name, it’s automatically copied to the clipboard. “Clear Names” removes them again.
Enable the Command Checker function with the click of a button
You can access the ribbon Command Checker by adding a parameter to the url, but if you’re like me and can never remember EXACTLY what to add, you like this feature:
Clicking the Command Checker button will add the Command Checker menu item to the end of the top menu:

and clicking that menu item will open the Command Checker itself:

Browse enum values directly on-screen

The “Option Set Values” button will open a dialog that lets you browse all enums and their respective values.
Facilitate debugging
There are three buttons that can make debugging a lot easier:

“Disable Form event handlers”, “Disable Business rules” and “Disable Form javascript” . I think you can guess what they do and how it can be helpful in debugging scenarios.
God Mode
There’s even a God Mode. God only knows what that does…

Impersonate user
There are a lot more useful functions, but I have of course saved the best for last.
There is an Impersonate user function. At the very top of the sidebar is a search box where you can look up a specific user to impersonate in the system. You will see the system as that user. Extremely useful for debugging security problems.
This is a function that is not supported by Microsoft, and it is really a miss in the system that nothing like that exists. So thank god for 3rd party extensions like this that can do it!
