How to Detect If Your Opponent Is Cheating (Free Tool On Github)

I Built a Chess Cheating Detection Tool - Here's How to Use It

The Problem
We've all been there. You play a great game, but something feels off. Your opponent plays perfectly, finds every tactic, never blunders. You're left wondering: Did they cheat?

I faced this too, so I built a tool to find out.

What I Built
A free, open-source chess cheating detection system that analyzes PGN files using Stockfish engine analysis.

It tells you:
- ✅ How accurate their moves were
- ✅ If they match computer suggestions
- ✅ Suspicion score (0-100%)
- ✅ Which specific games and moves were suspicious

How It Works
The tool compares each move against Stockfish (world's strongest chess engine) and calculates:

### 1. Move Accuracy (0-100%)
- 95-100%: Computer-level play
- 85-95%: Grandmaster level
- 70-85%: Strong club player
- <70%: Average player

2. Centipawn Loss
How much value was lost compared to the best move

3. Engine Match Rate
How often their move matched Stockfish's top choice

4. Suspicion Score
A weighted score combining:
- Accuracy (25%)
- Engine match rate (30%)
- Blunder frequency (20%)
- Consistency (15%)
- Phase performance (10%)

What the Output Looks Like

9-in-1 Visualization Chart (As shown at the bottom)

Shows:
- Suspicion timeline
- Accuracy distribution
- Error analysis
- Risk level breakdown

Detailed Report

How to Use It (Even If You're Not Technical)

Option 1: I'll Analyze for You (Easiest)
Just send me the username! I'll run the analysis and send you:
- PDF report
- Visual chart
- Simple verdict

Contact me:
- Email: tatarchess@gmail.com
- Instagram: @tatarldw
- Discord: tatarldw
- Or message me on chess.com!

Option 2: GitHub Repository
All code is open-source: Chess Cheat Detector Github

How Accurate Is It?

- **Clear cheating**: 95%+ detection rate
- **Strong players**: May show false positives occasionally
- **Best used as screening tool**, not definitive proof

Always manually review flagged games before reporting

What About False Positives?

Strong players can have high accuracy. The tool looks for patterns:
- Consistency across many games
- Unnatural blunder rates
- Selective cheating (white vs black)

Case Study: Real Detection

I tested this on a known cheater (later banned by Chess.com):

Results:
- 20 games analyzed
- 18 games flagged suspicious
- Average accuracy: 96%
- Suspicion score: 0.82 (VERY HIGH)

The suspicious games:
- Perfect opening preparation in rare lines
- 0 blunders in complex tactical positions
- Consistent 5-10 second moves regardless of complexity

Why I Made This Free?

Chess should be fair. Everyone deserves to know if their opponent played fairly or used engine assistance.