Run a chess tournament, and know why every pairing is what it is.
Lysander is tournament management for arbiters and organizers. It pairs individual Swiss tournaments by the FIDE Dutch System and can show the reason for each pairing.
What it is, and for whom
Lysander is for the people who run chess tournaments: arbiters who pair the rounds and organizers of clubs, opens and school events. It handles the work of an individual Swiss tournament from the list of players to the last result.
What sets it apart
- Every pairing can be traced to the rules
- The pairing engine works from the FIDE rules text in force from 1 February 2026 and records the decisions it takes, so an arbiter can ask why two players were paired and get an answer that points at the rule.
- The same input always gives the same pairing
- Pairing is deterministic. Where the rules leave a real choice open, the program says so instead of hiding it.
- Manual pairings are checked
- An arbiter may pair by hand. Lysander checks the pairing against the rules and records any deliberate override.
- Checked against an independent program
- The engine was compared with an independent reference pairing program on 10 000 random tournaments. They agree, except for one documented deviation of the reference program.
What works today
The Web application runs a whole individual tournament by the FIDE Dutch System:
- set up the tournament and add players, late entries, withdrawals and requested byes;
- pair each round, with the reasons for the pairings, or pair by hand with the check above;
- enter results and correct them later, and look back through every round;
- keep the tournament in your own browser: once the application has loaded it works without a network, with no account and with nothing sent to a server;
- save a tournament to a file and open it again, import and export TRF-2026 files, and print pairings, results and the list of participants;
- export a page file for the players: one file with the pairings and results to put on a screen or send out.
Not available yet: standings with tie-breaks, online publication of pairings, and installers (see Downloads). Nothing here describes a feature that does not exist.
The Web application
It runs in a current browser, with the pairing engine inside the page. There is nothing to install.
The address of the Web application is not set for this build of the site.
Downloads
Licence
Lysander is free of charge. It is not open source: the end-user licence lets you use it for any lawful purpose, including running tournaments for a club or an event, and does not let you copy it, pass it on or change it. The tournament files you make are yours.
Read the end-user licence (plain text)