I was working on a GUI calculator for personal use, that i intended to possibly release had i ever finished it, but I took a break from the game, cause life, and never really continued it.
It's done with Python and I had tried to mimic the game GUI to the extent possible. There's code for saving/loading character data, but it wasn't implemented in the GUI yet. The equipment options were culled from an equipment master list, that i had intended to make (may have made) a separate thing to edit/add new equips (particularly because of augments). In this way, this separated it from other calculators where one inputted trait values directly. In mine, they're pulled right from the equipment, job,race data. I was going to do a recursive comparative option, but I realized it's multi-instance so you could just open up another window to make comparisons.
As far as i know, the calculations, caps, and order of operations (which can be seen in blue text printed to the register in that left pane) were accurate as of a couple months back. I was in the process of transferring register printing into the GUI text seen under the 'equipment menu'. When i last worked on it. Keeping a minimalist approach, the job titles, aren't titles, they're buttons. So they'd bring up Job specific merit window not unlike the 'merit group 1 window'. I think i even implemented parts of the Gift system.
I intended to implement WS/magics (it was intended for my Blue Mage)but never got around to it.
most of the game mechanic formulas were culled from various ffxi sites or spreadsheet fare. Some are my own. So I can't even really say what's mine or what's someone else's mathematical work for credits.
I really wanted to implement a feature that would allow the importing of game gear, but that's beyond my skill level. The code's in python as i said, but if anyone wants it as skeleton code to finish or transmute into another language to release, let me know. As I don't actively play the game anymore, I don't really have the inclination to finish it. Unless someone pays me :P