QUICK ANSWERStart with the tool that matches your immediate input.
Open JSON Formatter and Validator first when its stated purpose matches the result you need now. Use XML Formatter only when it solves a separate next task.
This guide is for developers, analysts, testers, and technical writers. Start with JSON Formatter and Validator when your immediate task is to open the original JSON Formatter and Validator and complete the task with a focused browser-based interface. Move to XML Formatter only when you also need to open the original XML Formatter and complete the task with a focused browser-based interface.
The goal is not to run two tools automatically. It is to finish the first narrow task, inspect its result, and then decide whether XML Formatter solves a genuinely different next step.
Both tools sit in Developer & Data, but they handle different inputs or outcomes. Keeping those roles separate reduces repeated work and makes verification easier.