This is the exact reason I built the app :)

I tried to use the Chrome Dev Tools as much as I can (e.g. btoa/atob function to work with base64), but it takes too many unnecessary steps.

Now I just use the app and add any missing tools I found in my workflow.

Same. I always check the source for them to ensure all work is being done locally, but it still feels wrong. Would be cool to have a browser feature that disables form submission and JS network requests for specific sites.