Chess engines: what they are and which are the best

Did you know a free program today can spot you three moves and still win? That’s what a chess engine does: software that evaluates millions of positions per second and finds the best move in any situation. It plays far better than any human, including the World Champion.

Let’s look at where all this came from and, more importantly, how you can use it to improve your game.

How we got here: the history in five minutes

In the seventies, grandmasters laughed at the first programs. They played very badly. One of the scientists involved in those tournaments said something that’s been repeated ever since: “They’re laughing today, tomorrow they’ll be asking us for advice.” He was right.

The turning point came in 1997. Garry Kasparov, considered by many the best chess player in history, lost a match against Deep Blue, an IBM supercomputer that cost tens of millions of dollars. It was a shock to the chess world.

But here’s the interesting part. Today you don’t need millions of dollars. Your home computer, with a free program, comfortably beats any Grandmaster. The progress has been brutal.

The best chess engines

Let’s go through the names you need to know.

Stockfish — the free king

Stockfish is the strongest engine in the world among the open source ones. Free, no installation, and it runs directly in the browser. It has won the TCEC (the world championship for engines) multiple times. Its Elo rating is over 3700 points, far above any human player.

If you’re only going to use one engine, make it Stockfish.

Leela Chess Zero — the artificial intelligence

Leela Chess Zero (Lc0) doesn’t work like the others. Instead of calculating moves with programmed rules, it learned to play on its own through artificial intelligence, starting essentially from zero. The result is a creative, surprising style that has won over many enthusiasts.

Komodo and other commercial engines

Komodo is another top-level engine, well known for its positional style and its ability to calculate deep variations. There’s a paid version and a free one (Dragon). You’ll also find names like Houdini, Fritz or Ethereal in computer competitions; all of them extraordinarily strong.

The difference between them for an amateur player is almost irrelevant: they’ll all show you your mistakes perfectly.

What’s an engine good for if you’re a beginner?

It might seem like such a strong program is only useful for professionals. But that’s not the case.

There are two key uses that will help you improve:

1. Analyzing your games. After playing, paste the PGN into the viewer and the engine marks your mistakes. Not with punishment, but by pointing out which move was better and why. It’s the most effective study method I know.
2. Exploring specific positions. Want to understand a trap in the openings? Set up the position, analyze it with the engine, and see exactly what happens in each variation.

If you want to know how to improve at chess, analyzing your games with an engine is one of the most important steps. Beginners and Grandmasters alike do it.

How to use Stockfish right here

You don’t have to install anything. On this site you can play against the computer directly in your browser, with Stockfish running in real time.

You can also paste any position in FEN notation to analyze it. FEN notation is simply a way to write a board position as text, like a photo in code.

Let’s try a practical example: paste the PGN of your last game into the viewer below, click load, and watch where the engine marks mistakes. In five minutes you’ll learn more than reading theory for an hour.