About
I'm Shan, founder of Aeonic Frets: a player, a collector, a reseller, and a software engineer by trade. I couldn't find software that worked the way a guitar shop works, so I built my own. It runs my shop every day.
The shop
Like a lot of players, I picked up a guitar and never really put it down. Over the years I've owned, played, restored and photographed hundreds of instruments, from everyday workhorses to rare collector pieces, and opening a case still hasn't gotten old.
Aeonic Frets grew out of that. I inspect every guitar myself, photograph it, and describe it honestly, flaws included. Then it goes up on Reverb, on my own storefront at aeonicfrets.com, on Sweetwater Gear Exchange and on eBay.
The problem
As the shop grew, I went looking for software to run it and found nothing made for the way a used-gear shop works. Every guitar is one of a kind. Each one is bought, inspected, set up and photographed before it's listed, then sold on several marketplaces at once — and what it really made only shows once every fee, part and repair is counted against what I paid.
The tools I found were built for stores restocking the same new models, or for reselling things that don't have a condition grade. None of them could tell me what a guitar actually made. None of them took it down everywhere the moment it sold somewhere.
So I did it by hand: every guitar typed into every marketplace, every cost in a spreadsheet, and every sale a race to pull the listing everywhere else before a second buyer paid for a guitar that was already boxed up. That works for a few guitars a month. At the pace the shop sells now — about 100 a month, half of them within a week of listing — it doesn't work at all.
From Aeonic Frets' own records in BacklineSync, rounded, and the pace the shop sells at.
The software
I'm a software engineer by profession. When the tools didn't exist, I wrote them — one problem at a time, each one a problem I'd had that week. Every version was built because the one before it couldn't keep up.
2024
Every guitar, every cost and every sale in spreadsheets, and every listing typed out again for each marketplace. It held together until the shop outgrew it.
2025
The shop moved into a Power Apps app I built: inventory, costs and sales in one place, and flows on a timer copying listings from Reverb to the storefront and to Sweetwater. A guitar that sold waited for the next run to come down.
April 2026
Rebuilt from the ground up: inventory, purchases, the real profit on every guitar, and inspections that print a condition sheet for the listing.
July 2026
Sync moved inside it. Listing on Reverb became the only thing I did by hand — everything else followed from it — and a sale anywhere took the guitar down everywhere in seconds, instead of at the next timed run.
September 2026
Rebuilt once more, so other shops could use it. Aeonic Frets moved across on September 25 — every guitar, sale, photo and inspection — with every total matching to the cent.
October 2026
eBay was connected directly rather than through the storefront, and BacklineSync opened at backlinesync.com to any shop that sells in more than one place.
Today
Every feature in BacklineSync was built for my own shop first, then refined over years of working out how a shop like mine should run. The inspection checklist every new shop starts with is the one I run on every guitar I buy: 29 questions, in the order I work down the instrument. The price rules are the ones I set on my own listings. The sync is what keeps my guitars from selling twice. There's nothing in it I don't use to run Aeonic Frets.
So you won't be the one testing it. The trial and error already happened, in my shop, on my guitars.
This isn't software from a big development company. It's built by a player, collector and reseller who needed it, and it still runs my shop every day.
— Shan, founder of Aeonic Frets
7 days of Pro, with every marketplace you connect kept in step. No card until you decide to stay.