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Is Stockfish 12 free?

Stockfish 12, the latest version of the open source Stockfish chess engine, is 100% free for you to download and use. Both personal and commercial use are permitted under the GNU GPLv3 license. Let‘s dive into everything you need to know about getting and using this powerful chess AI.

A Brief History of Stockfish

Stockfish first emerged on the chess scene in 2008, created by Norwegian programmer Tord Romstad. Early versions already showed immense promise, eventually growing in strength to surpass open source rival Rybka.

Key releases over the years:

  • 2016 – Stockfish 8 gained worldwide acclaim after convincingly defeating Komodo in TCEC Season 9.
  • 2018 – Stockfish 10 introduced NNUE evaluation, taking playing ability to new heights.
  • 2020 – Stockfish 12 enhanced multi-threading up to 512 cores.
  • 2022 – Stockfish 15 introduces further NNUE improvements and exceeds 3800 Elo on some lists.

As you can see, Stockfish progresses in leaps and bounds thanks to its tireless development community!

Just How Strong is Stockfish?

Stockfish dominates the chess engine world with an estimated Elo rating above 3500. The current version Stockfish 15 likely exceeds 3800 Elo based on recent match results.

To put this in perspective, world champion Magnus Carlsen peaks around 2880 Elo. Stockfish would almost certainly deliver a crushing victory with a score such as 98% over even the greatest human player.

Against rival engines, Stockfish still demonstrates an overwhelming edge. Here are win-loss percentages from a match against Stockfish 11:
Stockfish match results
As you can see, Stockfish 12‘s advantage is astounding. It convincingly won over 91% of the game pairs played.

Technical Optimizations

So how does Stockfish achieve such superhuman performance? The engine utilizes a range of optimizations:

  • Efficient bitboard representation to track positions.
  • Alpha-beta pruning to deeply search critical lines.
  • Null move pruning and extensions to improve analysis.
  • Multi-threaded support to leverage up to 512 cores.

Combined together, these enhancements enable Stockfish to reach depths of over 60 plies in many positions!

Neural Network Evaluation

A breakthrough came with Stockfish 10‘s introduction of NNUE (Neural Network Universal Evaluation). This machine learning approach analyzes positions more accurately. By integrating deep learning alongside traditional search, NNUE evaluation has further solidified Stockfish‘s place at the top.

Getting Started with Stockfish 12

One of the great things about Stockfish is how easy it is to download and start using.

Desktop Download

To use Stockfish 12 on your Windows, Mac, or Linux desktop, simply:

  1. Go to stockfishchess.org/download
  2. Download the executable for your OS.
  3. Open the file and Stockfish is ready to go!

Now you can integrate Stockfish with chess GUIs like Chessbase or load engine matches directly from the executable.

Mobile Options

Stockfish offers excellent mobile apps for Android and iOS. You can analyze positions on the go or play against the engine with Elo rating up to Grandmaster level:

  • Stockfish Chess on Android – Completely free.
  • SmallFish/Stockfish on iOS – Free version available.

Play Online

One of the most convenient ways to play against Stockfish is online:

  • Lichess.org – supports game analysis and matches versus Stockfish AI.
  • Chess.com – features Stockfish bot opponents up to level 10.
  • Chesstempo.com – solves Stockfish puzzles and custom board positions.

I highly recommend lichess.org in particular for the friendliest Stockfish experience. You can even see server-side analysis during games!

How Does Stockfish Work?

Under the hood, Stockfish utilizes sophisticated evaluation and search techniques to master the game of chess.

The evaluation function aims to accurately assess board positions. It considers elements like:

  • Material balance
  • Piece activity
  • Pawn structure
  • King safety

The search then builds upon this evaluation by looking ahead many moves with alpha-beta pruning. Given enough time, Stockfish can see ahead 20 moves or more and confidently select the best continuation.

These core techniques enable Stockfish to play at super-GM strength. The open source codebase allows ongoing improvements as well.

Stockfish vs. Other Chess Engines

How does Stockfish compare against other top chess AI? Here is a quick rundown:

Leela Chess Zero

Like Stockfish, Leela is completely open source. It uses neural networks evolved through deep learning. While once thought to have surpassed Stockfish, Leela lags again in recent seasons. But it remains one of the top 3 engines.

Komodo

Komodo dominated TCEC over four seasons but has fallen behind the open source engines. Komodo is commercially developed by Mark Lefler and features highly aggressive play.

Houdini

Once a rival to Stockfish, Houdini‘s commercial development has stalled. It is now clearly ranked behind Stockfish, Leela, and Komodo at the top tier of chess AI. But Houdini still plays at super-GM level.

Final Thoughts

As you can see, Stockfish remains firmly at the cutting edge of computer chess. The ongoing open source development continually improves Stockfish‘s incredible power.

I hope this guide gives you a great overview of how you can access Stockfish. Please let me know if you have any other questions! I‘m always happy to help fellow chess enthusiasts make the most of this remarkable free engine.