This is unofficial Path of Exile Skill Tree app.
It allows you to create builds for any Path of Exile character and share them with a build link.
You can specify your weapon and main skill type and see combined totals for all relevant stat increases like damage, crit, attack or cast speed etc
It include full jewel support for jewels with radius, this include modifying tree in radius according to jewel rules.
You can enter your gear totals for life, mana and energy shield and see exact values for Max Totals, Regen and Leech Cap.
You can select auras and other reservations and see how much life and mana you have unreserved.
You can enter you skill and support gems and see how much they would cost to cast and how long can you sustain casting them.
Overview of all features is available here:
https://www.youtube.com/watch?v=G8QM16bFLbE