Chiron 5 is the latest version of the chess engine Chiron, released in July 2021.
Chiron 5 is much stronger than Chiron 4, supports multiple processors, Polyglot, CTG and Arena opening books, several endgame tablebases formats (Syzygy, Gaviota, Nalimov, Scorpio). If you want a chance to win against Chiron, you can limit its playing strength.
Chiron comes in both Chessbase and Open Exchange formats.

CHIRON IS A CHESS ENGINE THUS NEEDS A CHESS GUI TO BE USED.
RUN THE APP TO VERIFY YOUR LICENSE BEFORE PLAYING WITH IT IN A GUI.
BUYERS OF THE WINDOWS VERSION GET THE ANDROID ONE FOR FREE.

Chiron's main features are:
• playing strength of about 3240 Elo points on single core (CCRL 40/4)
• parallel search for up to 512 threads
• adjustable playing strength with autolimitation of book knowledge
• support for UCI and Winboard2 communication protocols
• MultiPV and searchmoves for game analysis
• support for Chess960
• support for Polyglot opening books
• support for CTG opening books
. support for Arena opening books
• support for Syzygy bases
• support for Gaviota tablebases
• support for Nalimov tablebases
• support for Scorpio bitbases
• smart detection of pawn blockages

Chiron 5 is about 110/120 points stronger than Chiron 4. Most of the gains come from improvements in search and move ordering but also the evaluation has been improved and tuned by playing several million games.
Here’s a list of the other main changes:
• support for 7-men Syzygy Bases
• improved time allocation
• support for Arena (.abk) opening books. The params saved in the book are used to choose the moves
• a second opening book can be used
• Elo limits have been retuned
• some other minor bug fixes

Major chess GUIs:
• Chess For Android (free)
• Droidfish (free)
• Scid on the Go (free)
• Chessbase Online (commercial)
• Chess PGN Master (commercial)

For a description of all the options please visit the official website: http://www.chironchess.com/support