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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
https://www.poeoverlay.com/ - This will do price checking and also gives you convenient buttons for trading (join party, travel to hideout, open trade, leave group, etc). Once you get into trading this saves you a lot of wrist life. I personally used PoE Trades Companion, an Autohotkey script but it looks like it isn't supported anymore so I don't want to recommend it as it may stop working at anytime.
https://snosme.github.io/awakened-poe-trade/download - Useful add-on, primarily useful for price checking (mouse-over item -> Press CTRL+D) but can also store search strings (rolling maps, Gwennen, crafting) and quick search/OCR for Heist targets.