ProjectResolute has been a chess fan since he was a kid. He now enjoys playing on chess (dot) com and various computer chess programs.
Chess engines are a great tool to have. Whether they are used for analyzing games, accurately converting a large advantage into a win, studying openings, or watching cyber chess warfare, if they are used correctly, they can help any chess player improve.
Any avid chess player can and should download at least one strong chess engine. However, there are thousands of engines out there and not all of them are created equal. Some of them have a fairly good rating on various chess engine rating lists, but they don’t function well. Some have various problems such as the inability to set search depth, searches longer than the set time limit, or crashes every now and then.
This can be a pain, although most engines that have these issues are free for anyone to download. To avoid this potential frustration, I’ve decided to make a list of the five best free chess engines. These engines all follow the Universal Chess Interface protocol (UCI for short), and can be used in any UCI-compatible chess program.
All of these engines are 100% functional and have quite a few configurations to play with. They are also all extremely strong, although some can be set to play at a more human level, too. Please note that the rating given to these UCI chess engines aren’t mine, but I get them from a 3rd-party source, which tests hundreds of chess engines and apply a rating to them. The link above will take you to the rating list I used for this article.
Okay, I’ve blabbered around long enough! Let’s continue to see what some of the best free chess engines are.
6 Best Free Chess Engines
- Stockfish Chess Engine
- Komodo Chess Engine
- Houdini Chess Engine
- Rybka Chess Engine
The Rating List I've Used
- Computer Chess Rating List
As I said, this site tests chess engines, and gives them a rating according to how well they do. While the site's ratings don't match up with FIDE's ratings, it is within the ballpark. I've used the list with 40 minutes per 40 moves time control
1. Stockfish Chess Engine
Stockfish is the strongest free chess engine. Stockfish 7, the latest version as of this moment of writing, has a rating of 3339. Although computer rating lists and official rating lists don’t necessarily match up, it is easy to say that Stockfish 7 is well beyond the skill of any grandmaster. It is also about 40 points above the next best chess engine!
The main co-authors of this engine are Tord Romstad, Marco Costalba, Joona Kiiski, and Gary Linscott. It must be noted that although these four are the main developers, this engine is open-sourced and thus was developed by a whole community of people. It is licensed under GPLv3, which basically means you can share to anybody, sell it as part of a larger project, and change the source code, as long as you either point back to where you got it, or supply the original source code.
The Stockfish project is actually a fork off of a chess engine called Glaurung, which is also open-sourced. People gradually started moving to stockfish, until finally Glaurung was abandoned altogether. It is interesting to note that the Glaurung chess engine’s rating is 2902, so Stockfish has improved upon its predecessor by 430 rating points.
Stockfish has several interesting configurations; the most noticeable in my opinion is the ability to scale down the skill level, so an average human can beat it. It has 21 different playing levels, and at level 0, although I have to think, I can beat it.
Another configuration that caught my eye is contempt. This setting is to make it play more risky moves. A setting of zero is default and considered neutral, a positive number up to 100 is more aggressive setting, and a setting of below zero up to -100, it will play for a draw.
While Stockfish is undeniably a strong engine, it is not the strongest. There is one engine that is stronger than stockfish according to most rating lists.
Download Stockfish Here
- Stockfish Downloard Page
Here's the Stockfish download page. There are versions available for Windows, Mac, Linux,, and Android.
2. Komodo Chess Engine (Latest Free Version)
Komodo chess engine is actually the strongest chess engine in the world. The reason why it isn’t first place in the list is because the latest version isn’t free. The most recent version of this engine is Komodo 10.1, which costs $59.96. This version has a current rating of 3379, which is 40 points above its “archenemy,” Stockfish.
However, with every new version of Komodo that is unveiled, there also becomes a past version available for free. Currently, Komodo 8 is available without charge, and this version has a rating of 3296. The free version is about 40 points below Stockfish 7 and 80 points below Komodo 10.1. So even with Komodo 8, you’re going to have a world-class chess engine.
The thing I wish Komodo would have but doesn’t is a setting to weaken its play. This is true for all versions. It is a minor inconvenience though because I mostly use UCI chess engines for game analysis, and if I want to, I can still limit its skill by search depth, which when set to one ply, plays quite stupidly.
Komodo 8 does have a configuration to control its aggressiveness, called draw score. The default setting is -7, and if you set it lower, (i.e. -15) it will play more aggressively, and if higher, it will try to play for a draw more often.
So, although the free Komodo chess engine isn’t quite as strong as Stockfish 7, I can’t think of a reason why one wouldn’t want to take time and download the chess engine. In fact, I bought the engine back when it was the latest and the greatest, and although it was a while back, it’s still among the strongest.
Download Komodo Here
- Komodo Download Page
Komodo 8 comes in a zip file, and contains versions for Windows, Linux, Mac, and Android
The Andscacs chess engine was first released in September of 2013. Since then, it’s only grown in strength. Its current release, Andscacs 0.872, has a rating of 3211 according to CCRL and has participated in stage 3 of season 9, where it came in 5th place.
The creator of this chess engine, Daniel José Queraltó, lives in the country Andorra. Hence the name of the engine, Andscacs, “And” for his country, “scacs” for the Catalan word escacs, meaning chess. Daniel got his inspiration for creating this chess engine from a variety of open-source engines such as Stockfish and Gull.
Unfortunately, this chess engine is no longer available for download. That said this article is long overdue for an update, and I will do so very soon.
Fire is another one of the top free chess engines. Originally called Firebird, this chess engine is usually among the top 10 in many rating lists. It's debatable whether Fire or Andscacs is the better engine since they are within 10 points difference in the CCRL rating list.
It originally started out as an open-source project, but later the code became closed. However, there is a fork off of fire 2.2, which has been rename Firenzina, which is still open-sourced. When the Fire chess engine became closed, the code was completely rewritten and doesn't contain any code from the chess engine Ippolit, as the original open-source version did.
- Fire Chess Engine's Home Site
Fire 4 is available for download at this link. There is only a 32 bit and 64 bit versions for Windows in the .rar file.
5. Houdini Chess Engine (Latest Free Version)
The Houdini chess engine is a very popular chess engine even though it is a distant 3rd place on most chess engine rating lists. Houdini 4 is the most recent version and it has a rating of 3255 on CCRL. It is a 3 time champion in the TCEC tournaments, which is considered by many to be the world computer chess championship. Only Komodo holds as many titles.
Rumor has it that Houdini 5 will be released for the final stages of TCEC season 9. Houdini 4 improved upon its predecessor by approximately 50 elo points. Will this Houdini 5 have a rating of around 3300? We’re going to have to wait and see. I personally have my doubts, since at the moment I’m writing this, Stage 3 of season 9 is already under way, and there’s no sign of Houdini 5 as of yet.
Whether or not a new version will ever be released, the free Houdini chess engine is also very strong. With a rating of 3197, Houdini 1.5a is a chess engine that a human will never stand a chance at winning. What’s more is that Houdini has an interesting style of play. Many chess players have remarked that this chess engine has a very romantic style of play, similar to such players like Paul Morphy and Mikhail Tal.
Download Houdini Here
- Houdini Free Chess Engine Download Page
The link for the free version of houdini is hard to find on this page. It's further down after talking about Houdini 4, and is labeled Houdini 1.5. There is only a windows version available.
6. Rybka Chess Engine (Latest Free Version)
I know that the Rybka chess engine is fairly outdated. Rybka 4, the last release, has a rating of 3160. This is around 30 points lower than the free version of Houdini! However, the latest release is still available for sale on Amazon & Chessbase. On Amazon, the engine costs about $50 and on Chessbase it costs a whopping $90.75! Even the latest version of Komodo’s cheaper!
Thankfully, there’s a free version too — Rybka 2.3.2a which has a relatively minuscule rating of 3024. So, why am I recommending this engine as one that every chess player should have? Because of a configuration that I think is quite handy! You can set the rating at which it works. With a range of 1200 to 2400, the lower one sets this rating the more mistakes they make.
The rating will not match up with a Fide rating though, so don’t go into a tournament saying that you have a rating of 1300 because you beat Rybka at that rating. That said, if you win a game at 1200, your rating will likely be higher than this. I have trouble defeating it at this level, and my rating on chess.com is around 1600!
Download Rybka Here
- Rybka Download Page
Here's the free version of Rybka. Sadly, it's only available for Windows.
Come Back Soon!
Thus ends my listing of some of the best free chess engines. Although the article is now drawing to a close, I encourage you to check back, since I’m planning on adding more engines to this page.
© 2016 ProjectResolute
Sorrowdy on April 24, 2020:
And where is Raubfisch? According my engine tournaments it is the best engine ever. And it's also free.
noob on March 10, 2020:
It's 2020 and this article makes zero mention of the new Neural Network engines Lc0, Leelenstein, Stoofvlees, all of which are significantly better than every engine above except Stockfish.
Chess Player on February 25, 2018:
Thanks! Good Job for the Source!
Erik on November 26, 2017:
Thanks, good job. Nice would be comparing chess GUIs, too.
Really? on October 27, 2017:
Check your spelling and grammar. Nothing added here beyond a rating list and some nonsense. You can find actual reviews elsewhere online, and links that aren't "hard to find." A chess "fan," really? Not a player, a fan? lol
ciarli on September 29, 2017:
what about 'demon' engine! I heard that it is prohibited because he can make any move and win again and is insulting Godmaster way of thinking!
Md. Shahinur Islam on August 30, 2017:
Whats the position of Chessmaster & Fritz in terms of ratings??
Reign Tibudan on July 27, 2017:
Thank you, you are so helpful
Kainoa Thomas Henao on May 24, 2017:
Hal on April 01, 2017:
Thank you.. :)
Thomas on October 23, 2016:
Very nice and competent review of the best chess programs - thanks! I wonder, however, if the new version of Houdini is not even stronger given it's current performance in TCEC Rapid - perhaps 100 -150 Elo points over version 4? Anyway - we'll see in the TCEC Super Final! Best Regards Thomas