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634 points david927 | 1 comments | | HN request time: 0.209s | source

What are you working on? Any new ideas that you're thinking about?
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nlh ◴[] No.41342681[source]
I’m a tech nerd rare coin & currency dealer! I took my two hobbies and combined them into a real business and I’m having the time of my life. Just launched a proper retail site here:

https://www.rarity7.com/

About 50% of my days are spend doing the coin dealer stuff - hunting for inventory, buying collections/doing appraisals, going to coin shows and buying and selling in person, etc.

The other 50% I’m writing code and building out the tech stack for this business. I’ve written the whole backend for the retail site myself, which includes my own inventory management system, sync with eBay and other marketplaces, etc.

I’ve also built out a research tool which includes an ML price prediction engine engine (which sounds fancy but is really just a tabular regression model).

Backend is written in Crystal because I love the language and there’s nobody stopping me from using it :) Frontend is all Svelte and they’re glued together using a mini framework I wrote:

https://github.com/noahlh/celestite

I probably have 5 years worth of ideas I still want to build and I wish I could spend even more time building it all, but it’s super fun actually using it in the real live marketplace so I’d never give that up.

Happy to chat about this stuff with anyone who’s interested or vaguely interested in numismatics.

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efishnc ◴[] No.41343439[source]
Very cool and super clean website! Talk about your infra please!
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1. nlh ◴[] No.41344751[source]
Thanks!!

Infra: I was hosted on Google Cloud for a while -- literally a single VM running Docker Compose, but I decided I wanted something a bit more flexible and interesting, so last month I switched everything over to Fly.io and I am incredibly happy with them. It's just so easy and fun to manage.

The retail site (rarity7.com) is just a small VM running a Crystal server process to handle web requests. Image hosting is all done on Cloudinary. My backend / inventory management / trading + research engine is a separate Crystal process in a separate VM. Both connect to a Fly Postgres DB. There's one other service which is a small python process on another VM which is doing inference on my regression model. That's super lightweight and I don't need any GPUs to do the inference (tabular data is nice like that).

Overall it's really nothing fancy and it works quite well. A few web-serving VMs and an inference service for my pricing model. I train/retrain the model a few times a year on a local box (my repurposed gaming rig running a 2080Ti).