Chess engines have transformed how we learn and play chess in the 21st century, providing us with instant analysis and helping players of all levels improve their skills.
And the best part? You can find many high-quality free chess engines online!
In this article, I’ll introduce you to the 10 best free chess engines available today. I’ll also explain their key features so you can decide which one is best for you.
The 10 Best Free Chess Engines
I’ve compiled a list of 10 powerful chess engines that are open-source and free for download in 2023.
I’ll discuss each engine based on its playing strength, search algorithms, and other key features so that you can find the one that best suits your preferences.
1. Stockfish
Stockfish is an open-source chess engine that consistently tops chess engine ratings, and for a good reason! It’s the strongest free chess engine available with an estimated Elo rating of over 3500.
The chess engine can use up to 512 CPU cores, resulting in stronger and more efficient gameplay. Apart from that, the engine uses aggressive pruning and late move reductions aside from the alpha-beta search algorithm.
Furthermore, it has a large transposition table that can store up to 1 terabyte of information about previous game states.
Stockfish also has many built-in analytical tools, such as game analysis, position analysis, and opening book analysis. Additionally, it can support a variety of input and output formats, including PGN, EPD, and FEN.
2. Berserk
Berserk is another open search engine with high playing strength. Its Elo rating is estimated to be around 3500.
It can use two board representations: Bitboards and Magic Bitboards. The latest version of the engine features improvements in search algorithm, time management, and evaluation.
The engine has its network architecture, which includes NNUE evaluation, reverse futility pruning, quiescence search, and singular extensions.
Like other chess engines, you can easily import the PGN of previous games on Berserk for analysis.
- Leela Chess Zero
Leela Chess Zero is another open-source engine with high playing strength. Its estimated Elo rating is around 3500.
The engine is inspired by the principles of Deepmind’s Alpha Zero and AlphaGo Zero research, which uses a neural network to learn from playing with itself millions of times.
Unlike other chess engines that use AlphaBeta search, Leela Chess Zero uses a Monte Carlo Tree Search (MCTS) called Puct.
For optimal performance, you should run this engine on a CUDA-supported GPU. Using a GPU without CUDA support can cause the engine to run slower and provide inferior results.
4. Komodo
Komodo is an open-source engine that was developed by rewriting an older engine called Doch and rewriting it into C++11. Its Elo rating is estimated to be around 3400.
Unlike other engines, which rely on depth, Komodo relies on evaluation, resulting in a unique positional style.
Some other features include the ability to support up to 64 CPU cores, Syzygy endgame tablebase, and Fischer random chess.
Further, you can save the engine’s analysis of a position to resume analysis later. There’s also an added feature that lets you see how the engine makes long-term sacrifices of pawn structure.
5. Ethereal
Another open-source search engine you can try is Ethereal. Its playing strength is quite high, with an Elo estimated at around 3400. It’s been influenced by successful engines like Stockfish.
Ethereal uses different enhancements in addition to the conventional alpha-beta search. It includes reduction and pruning to improve performance.
In addition, the engine uses extension techniques to evaluate the game tree and explore moves.
6. Rubichess
Rubichess started as a personal project aimed at practicing C++ programming. Over the years, it became highly competitive and is now featured in most chess rankings.
It has high playing strength, with an estimated Elo ranking of almost 3500. It’s UCI-compliant which means you can use it with different graphical user interfaces like Arena, CuteChess, or BanksiaGUI.
It uses Alpha-Beta search with various enhancements such as Alpha-Beta pruning, quiescence search, and transposition tables.
7. Revenge
The Revenge chess engine, also known as Predone, is a powerful, open-source engine with an estimated Elo ranking of almost 3500.
The engine is compatible with both Windows and Linux operating systems but, similar to Rubichess, requires a GUI.
In 2023, Revenge incorporated a larger neural network. This update significantly enhanced the engine’s strength across all game stages, especially in the endgame.
The engine also underwent advanced speed optimization in its search algorithm. This optimization ensures a faster and more efficient exploration of the game tree, leading to quicker and more accurate evaluations of positions.
8. Koivisto
Koivisto is another open-source chess engine known for its high playing strength. Its Elo rating is estimated to be almost 3500.
It’s implemented in C++ and uses advanced techniques like lazy SMP (Symmetric Processing), iterative deepening, and principal variation search. However, this engine requires a GUI before you can use it effectively.
Another notable key feature of Koivisto is its bitboard engine, which uses a specialized data structure to make calculations.
You can download the engine’s binaries on GitHub which is available for both Windows and Linux.
9. Booot
You can also try using Booot, another open-source UCI chess engine project. It also has high playing strength, with an estimated Elo rating of around 3400.
One of its key features is using rotated bitboards to determine sliding piece attacks. Using this technique allows it to have a more efficient calculation and evaluation of moves.
In terms of the search algorithm, Booot uses PVS (Principal Variation Search), including search enhancements like late move reductions, null move pruning, and internal iterative deepening.
10. Fizbo
With an estimated Elo rating of around 3300, the Fizbo chess engine provides high playing strength and you can download it for free.
The chess engine uses Chess Engine Communication Protocol. Currently, it’s only compatible with Windows and requires a CPU that supports pop-count instructions.
Fizbo employs iterative deepening and parallel searches using an improved PV splitting algorithm.
Conclusion
Chess engines have revolutionized the way we play and learn chess. Nowadays, chess players at all levels and from anywhere in the world have the resources they need to improve their skills.
What’s more, there are several top-notch options you can choose from in 2023. Take your pick from the 10 options we recommended and enjoy experimenting with new openings and tactical combinations.
