It is possible to run flows directly from the flow builder. Click on "Test flow" in the top-right corner. A sidebar appears where you set the input for the flow in JSON format. This is partially pre-filled in based on the required input schema. Click on "Run flow" to execute.
The blocks and connections that were executed are highlighted. This allows you to see where an error occurs. Also, a new icon is visible on executed blocks that lets you view the block's input and output data.
In the output above, you'll see that the request succeeded (status 200). You can expand items by clicking on it. Also, it is possible to copy the objects by clicking on the copy icon. When clicking once, this copies the JSON data. By clicking multiple times, you can copy JSON Schema and TypeScript definitions for this object. This is especially handy when you want further to process this data in subsequent blocks or scripts.
A block might have multiple executions during a single flow run. Only the debug information for the first and last execution is saved.