TF2 Arbitrage Dashboard

On backpack.tf, every item has people posting buy orders and people posting sell orders at the same time. Almost always the highest buy sits below the lowest sell, but every so often someone posts a buy order above what somebody else is already selling the same item for, and until one of them notices, you can buy from one and sell to the other. This dashboard watches the entire live listing feed and collects every one of those windows into a single table, biggest gap first.

Behind the page is a background worker that holds one connection to backpack.tf's event stream, keeps an order book for every item in memory, and only writes to the database when an item actually crosses into profit.

Click here to see the code on GitHub

Below is what the dashboard looks like while it is running.

The three cards along the top show the biggest gap it is currently tracking, how many items are profitable right now, and the average margin across all of them.

Clicking any item name opens that exact item variant on backpack.tf, so you can go check the listings yourself, as shown below. 

NOTE: Backpack.tf has no association with me or this project. This is just the site I use to get the data from.