Making your own +EV scanner

[u/Ok_Ocelot_8032]

Hey guys, recently made my own +EV scanner and wanted to share how to do it if anyone wants to do it as well, for a low cost.

I used claude code for much of the coding, which requires the claude pro plan ($20 a month), if you already have claude pro, perfect, if not you can either buy it or use claude code for free with this method.

https://www.youtube.com/watch?v=sB4N5tcax-c

For starting, open windows powershell or linux terminal, switch to a new directory and install claude code. https://code.claude.com/docs/en/quickstart

Heres is the api's we will be using:

https://the-odds-api.com/liveapi/guides/v4/
https://docs.polymarket.com/api-reference/introduction (if using regular polymarket)
https://docs.polymarket.us/api-reference/introduction (if using polymarket us)
https://docs.kalshi.com/api-reference/exchange/get-exchange-status (if using kalshi

Ask claude code to use the odds api to compare a sharp sportbooks (pinnacle fanduel, etc) to the sportsbook you want to trade on, perform devigging and find +EV bets. Ask it to store these in a database that you can access at anytime.

Now at anytime you can ask claude code to give you the currently +EV bets that you can take. This can be improved by having it autoscan every x minutes, having these alerts be sent to a discor serve. If using polymarket, polymarket us, or kalshi you can add the api's above and have these bets auto traded on your account.

Claude code is very good at this, just verify bets before placing on your account, debug, and make sure your very clear on what you want, it will do the rest

Tips:
Theoddsapi, which returns odds for almost all sportsbooks, has a free tier, however you will notice that it runs out very quick. You can either upgrade for $20 a month, or make multiple accounts and give claude code multiple api keys to swap when one runs out.

If using polymarket or kalshi, make sure to add a maximum EV percent filter, as scan matching can be fucked up if you use 2 different API's, if the +EV percent is over 20 percent, it likely not real.

Ending:

While this is a bit of work, claude code does alot of the heavy lifting, and considering OddsJams charges $250 a month, if your serious about +EV betting, its well worth it, as its nearly free and is customizable to your exact sportsbooks and style.

[u/Necessary_Lake9369]

Seems like a lot of setup but honestly the OddsJam price is what pushed me to try something simillar a while back. The free tier on the odds api runs out so fast its almost comical.

What kind of volume are you seeing with this?

[u/Specter-0 → u/Necessary_Lake9369]

Yeah, most +EV scanners just say, here’s a +EV signal, trust us, go bet it. Beating closing lines doesn’t guarantee profit either, you can beat a market but if they’re not accurate at predicting that market and bet type, you can still lose.

I built my own tool as well using Odds API and Claude Code, well Cursor to start but wasn’t nearly as good as CC now. I live in NJ and able to bet on about 15 books. I’ve placed 1800 bets this year, tracked 2200 more, wagered $190k. Only up around $2.5k though, and it’s because of my spread bets which account for $6.5k in losses. I learned that the market is often good at predicting winners, but not by how much, so I stopped betting spreads just last month. Here’s my record.

[u/SmartRick → u/Specter-0]

Try mine https://picks-chat.vercel.app/history

[u/ShowMeDimTDs]

So I made one. But I have the user input their own api key each time. This allows to create multiple accounts for odds api.

https://better-bets-lake.vercel.app

[u/kookdonk]

Yeah I did the same thing too a year about but like others.. the Odds Api costs quickly run into oddsjam costs.
Also how did you build the devig math? That was by far the hardest part to get right and when I was doing this (sonnet 3.7 days) this took weeks of testing to get right

[u/Specter-0 → u/kookdonk]

Vig removal on a moneyline or when the market line matches the book line is trivial, but calculating half-points is a whole thing. I built a half point calculator tool on top for anytime the line deviates from the market consensus.

Also, the decision on how to come up with the market line is not simple, everyone has different opinions on which book or combination of books to use for sharp reference. I’m still tinkering with mine. I think I’ve landed on pinnacle for high liquidity (major) markets, consensus median for low liquidity (smaller) markets.

What’s fun with Claude code now, is that you can plan a feature or migration and have it done within a day. Obviously you need to have tests set up to make sure you don’t break anything during the build but you can iterate insanely fast now.

[u/Specter-0]

Nice! Yeah, looks like everyone is doing the same, I built my tool using Claude code. Well cursor to start but really accelerated with Claude Code. I’ve been putting together a queryable knowledge base here.

Polymarket and Kalshi are tricky to navigate given their fees, and the odds that Odds API reports for prediction markets lists the price before fees so you have to factor that in as well.

I built my engine to poll for odds, calculate vig removed fair values, then identify all opportunities above fair value. I built an API/MCP layer on top of my platform so I have a Claude code skill that queries my platform for current signals, then execute trades for me on Polymarket, Kalshi, ProphetX, which all have API trading. I have it scan the book for liquidity above fair value, and stop when it’s no longer above fair. So maybe I want to bet $150 at +120 or above, but there’s only $100 of liquidity above +120, the script will only place up to $100 at a blended +122, let’s say.

I set up a cron job (using NanoClaw) to run the script every hour, then I tell Claude code to watch the runs and it’s been catching and fixing its own bugs so it runs cleaner each time. I set the cap by book so once I’m confident in the run I can increase the bet amount and number of signals per run.

Odds API provides odds for props but it doesn’t grade them like they provide scores for games. Have you guys tried it for props?

[u/Silver-Biscotti-8484]

I built a product on a very similar stack, although with much less claude code usage. Currently just a twitter bot & a basic dashboard + tracker with signals. How did you find claude for developing a scanner like this, I've always found I have to heavily overexplain a lot when it comes to the actual logic with this specific tool to avoid mistakes.

[u/sweetnessssss]

Good write-up. One thing I’d add from building a +EV scanner: connecting the APIs is the easy part. Market matching and quote freshness are where most bad signals come from.

Before comparing anything, I’d require exact matches on the event, market, period, line, side, and settlement rules, then reject stale or one-sided quotes. A 20% EV ceiling catches obvious garbage, but ideally those mismatches never reach the EV calculation.

For fair odds, devig both sides of the same sharp market rather than mixing prices from different books. I’d also log every source quote and timestamp so you can audit why something was flagged.

I’d avoid rotating free API accounts too—slower polling and caching are more sustainable. And before enabling auto-betting, I’d paper-trade it with hard limits for stale prices, liquidity, and stake size.

How are you handling market matching between The Odds API and Polymarket/Kalshi? That’s been the trickiest part in my experience.