Stockfish OnlineWorld's Strongest Chess Engine - Free in Your Browser
Use Stockfish 15+ with NNUE (Neural Network) technology completely free online. Analyze any chess position, find the best moves, and improve your game with the world's most powerful open-source chess engine. No download or installation required.
What is Stockfish?
Stockfish is the world's strongest open-source chess engine, consistently rated over 3500 Elo - far stronger than any human chess player. Originally developed in 2008, Stockfish has evolved through contributions from hundreds of developers worldwide and has become the gold standard for chess analysis.
The latest version, Stockfish 15+ with NNUE (Efficiently Updatable Neural Network), combines traditional alpha-beta search algorithms with modern neural network evaluation. This hybrid approach provides unprecedented accuracy in position evaluation, especially in complex middlegame and endgame positions.
Professional chess players, coaches, and enthusiasts worldwide rely on Stockfish for game preparation, analysis, and training. Now you can access this powerful engine directly in your web browser, completely free, without any downloads or installations.
Stockfish Online Features
NNUE Technology
Neural network evaluation provides human-like understanding of positions with superhuman calculation depth. More accurate than traditional engines.
Lightning Fast
Analyzes millions of positions per second using WebAssembly technology. Get instant analysis results even on mobile devices.
3500+ Elo Strength
Rated far beyond world champion level. Provides perfect analysis for players of all skill levels from beginner to grandmaster.
Multi-PV Analysis
See multiple best move variations simultaneously. Understand alternative plans and compare different strategic approaches.
Precise Evaluation
Get exact position evaluations in centipawns. Understand who's winning and by how much at any point in the game.
Browser-Based
No downloads, no installations. Works directly in your browser on any device. Start analyzing immediately.
How to Use Stockfish Online
Step 1: Load Your Position
You can analyze any chess position using several methods:
- Upload a PGN file of your game
- Paste PGN text directly
- Enter a FEN string for a specific position
- Set up pieces manually on the board
- Start from the initial position and play moves
Step 2: Configure Analysis Settings
Customize the engine settings based on your needs:
- Depth: Set analysis depth (10-25+ plies). Higher = more accurate but slower
- Multi-PV: Choose how many best move variations to show (1-5)
- Threads: Adjust CPU usage for faster analysis
- Hash Size: Allocate memory for better performance
Step 3: Start Analysis
Click the "Analyze" button and Stockfish will begin evaluating the position. You'll see real-time updates showing the best moves, evaluation score, and principal variation (the sequence of best moves for both sides).
Step 4: Understand the Results
Stockfish provides several types of information:
- Evaluation: Numbers like +1.5 mean White is better by 1.5 pawns
- Best Move: The strongest move in the current position
- Principal Variation: The expected continuation if both sides play perfectly
- Depth: How many moves ahead the engine has calculated
- Nodes: Number of positions evaluated
Step 5: Explore Variations
Click on suggested moves to see how the position would change. Compare different variations and understand why certain moves are better than others. Use this to improve your chess understanding and find your mistakes.
Understanding Stockfish Evaluation
Evaluation Scores Explained
White has a slight advantage (about half a pawn)
White has a clear advantage (1.5 pawns better)
White has a winning advantage
Position is equal, balanced chances for both sides
Black has a significant advantage
Checkmate in 5 moves (forced win)
Common Stockfish Terms
- Depth
- How many half-moves (plies) ahead the engine has searched. Higher depth = more accurate.
- Nodes
- Number of positions evaluated. More nodes = more thorough analysis.
- NPS (Nodes Per Second)
- Analysis speed. Faster devices achieve higher NPS.
- PV (Principal Variation)
- The best sequence of moves for both sides according to the engine.
- Multi-PV
- Shows multiple best move options, useful for understanding alternatives.
Tips for Effective Stockfish Analysis
✅ DO
- • Use Stockfish to verify your own analysis first
- • Try to understand WHY moves are better
- • Focus on critical positions and turning points
- • Compare multiple variations in complex positions
- • Use it to prepare openings and study endgames
- • Let it run longer for important positions
❌ DON'T
- • Blindly follow engine moves without understanding
- • Rely on it during your actual games (that's cheating!)
- • Analyze every single move of every game
- • Ignore your own chess intuition completely
- • Expect it to solve all your chess problems
- • Use shallow analysis for complex positions
Stockfish Online FAQ
Is Stockfish really free to use?
Yes! Stockfish is completely free and open-source software. You can use it online through our website at no cost, with no registration required. There are no premium features or paywalls - everything is free forever.
How strong is Stockfish compared to human players?
Stockfish is rated over 3500 Elo, which is approximately 800-1000 points higher than the world's best human players (around 2800-2850 Elo). To put this in perspective, even world champions have virtually no chance of beating Stockfish in a match.
What is NNUE and why is it important?
NNUE (Efficiently Updatable Neural Network) is a neural network evaluation system that makes Stockfish much stronger, especially in complex positions. It combines traditional chess algorithms with machine learning, resulting in more human-like positional understanding with perfect tactical calculation.
Do I need to download Stockfish?
No! Our online version runs entirely in your web browser using WebAssembly technology. There's no need to download or install anything. Just visit our website and start analyzing immediately.
Can I use Stockfish on my phone or tablet?
Yes! Stockfish works on all modern devices including smartphones and tablets. The analysis runs locally on your device, so you can even use it offline once the page is loaded.
How accurate is Stockfish analysis?
Stockfish is extremely accurate and is considered the gold standard for chess analysis. At sufficient depth (18-20+ plies), its evaluations and move suggestions are essentially perfect for practical purposes.
What depth should I use for analysis?
For most positions, depth 18-20 is sufficient. Tactical positions may benefit from deeper analysis (22-25+), while simple positions can be analyzed at lower depths (15-18). More depth takes longer but is more accurate.
Can Stockfish solve all chess positions?
While Stockfish is incredibly strong, chess is too complex to be completely solved. However, for practical purposes, Stockfish's analysis is accurate enough that any differences from perfect play are irrelevant for human players.
Is it cheating to use Stockfish?
Using Stockfish to analyze your completed games is perfectly fine and encouraged - it's how you learn and improve. However, using any engine assistance during live games is cheating and will get you banned from chess platforms.
How does Stockfish compare to other chess engines?
Stockfish is consistently ranked as the strongest chess engine in the world, regularly winning computer chess championships. Other strong engines include Leela Chess Zero, Komodo, and Houdini, but Stockfish typically performs best.
Can I adjust Stockfish's playing style?
Stockfish always plays objectively for the best moves. Unlike some engines, it doesn't have different playing styles. However, you can adjust the analysis depth and multi-PV settings to see different move options.
Why does Stockfish sometimes change its evaluation?
As Stockfish analyzes deeper, it may discover new tactics or strategic ideas that change the evaluation. This is normal - deeper analysis is more accurate. Evaluations typically stabilize after reaching sufficient depth.
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