Building a Real-Time Betting Odds Monitor with Arbitrage Detection

I recently built PariScrapper — a real-time betting odds monitor with an API, basic arbitrage detection, and a Streamlit dashboard for live visualisation of odds, implied probabilities, and bookmaker margins.

DISCLAIMER - BETTING IS RISKY AND I AM NOT PROMOTING IT

This blog walks through the math behind betting odds, how bookmakers make money, and how I built this project to track odds and detect arbitrage opportunities in real time.

---

1. Understanding Betting Odds (With a Simple Example)

Betting odds tell you how much you can win relative to your stake.

For example:

• India: 1.14

• Australia: 5.60

If you bet ₹200:

• On India: 200 × 1.14 = ₹228 → ₹28 profit if they win.

• On Australia: 200 × 5.60 = ₹1120 → ₹920 profit if they win.

The formula is simple:

$$\text{Payout} = \text{Bet Amount} \times \text{Odds}$$

---

2. Can You Bet on Both Teams and Always Win? (Arbitrage Betting)

This is where arbitrage betting comes in.

It’s a strategy where you bet on all possible outcomes in such a way that you guarantee profit no matter what happens.

The key condition for a two-outcome event:

For two outcomes with odds ( a ) and ( b ), the key condition is:

$$\frac{1}{a} + \frac{1}{b} < 1$$

Where ( a ) and ( b ) are the odds for both teams.

---

Example:
India: 1.14
Australia: 15.60

Substituting:

$$\frac{1}{1.14} + \frac{1}{15.60} \approx 0.91 < 1$$

This means you can split your stake to guarantee profit.

• Bet ₹186.38 on India.

• Bet ₹13.62 on Australia.

• No matter who wins, you end up with ₹198.85 → a small risk-free profit.

This doesn’t happen often — but when it does, it’s a free money situation.

---

3. How Do Bookmakers Always Make Money?

Bookmakers aren’t in the business of losing.

They bake in a margin (or "overround") by slightly skewing the odds.

The implied probability of each outcome is:

Probability=1Odds\text{Probability} = \frac{1}{\text{Odds}}

For our example:

• India: 1 / 1.14 ≈ 87.72%

• Australia: 1 / 5.60 ≈ 17.86%

Total: 87.72 + 17.86 ≈ 105.58%

That extra 5.58%? That’s the bookmaker’s profit margin.

---

4. The Project: Real-Time Odds Monitoring & Arbitrage Detection

I wanted to monitor live odds, expose them via an API, and visualize them in real time.

So I built PariScrapper, which has three main components:

a) Flask API (main.py)

• Uses Selenium to scrape live odds from Parimatch.

• Runs a background thread to continuously update odds for a given event.

• Provides a REST API at /odds?event=<id> to fetch the latest data.

b) Arbitrage Detection (arbitrage.py)

• Periodically queries the API.

• Checks if the arbitrage condition is met.

• Logs alerts when opportunities are found.

c) Streamlit Dashboard (streamlit_ui.py)

• Displays real-time odds, implied probabilities, and bookmaker margins.

• Plots historical trends for better insights.

---

5. Key Features

• Live Odds Monitoring: Continuous updates from the betting platform.

• Arbitrage Detection: Detects when a guaranteed profit opportunity arises.

• Bookmaker Margin Estimation: Shows how much profit bookmakers make.

• Streamlit Dashboard: Interactive visualization for odds & probabilities.

• REST API: Easy access for programmatic use.

---

6. What’s Next?

I’m planning to add:

• Support for multiple bookmakers (to find cross-platform arbitrage).

• Custom market selection (e.g., over/under, totals).

• Advanced notifications (Telegram/email alerts when arbitrage appears).

• Better scaling (switching to async scraping for many events).

---

Disclaimer

This project is for educational purposes only. Betting involves financial risk, and arbitrage opportunities are rare and time-sensitive. Use this tool responsibly.

---

Check it out on GitHub: PariScrapper