The licence in plain words.

The software is provided “as is”

Kingfisher is provided as is, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

That is the MIT licence's own wording, in its own words. It means exactly what it says.

No warranty of correctness

Kingfisher is a chess research tool. The engine analysis it shows is the engines view, the reference data it queries is the data the upstream published, and the assessment you reach with it is your own. Kingfisher does not certify that a move is good, that an opening is “best”, that a result is “correct”, or that any number it displays is a fact about a chess position rather than a measurement of how a population played it.

A statistic labelled 15,432 games is a count of games in a specific upstream archive. A statistic labelled Wins 53% · 4,200 games is a sample statistic on that count. Kingfisher does not extrapolate, blend, or rank sources. The application will sometimes refuse to answer a question; that is a deliberate product decision, not a defect.

No warranty of availability

The web build is hosted on Vercel. Vercel's own availability terms apply. The macOS application is a downloadable DMG; once downloaded, the application runs on your machine and your machine's availability governs. There is no service-level commitment on the web or the desktop, and the maintainer reserves the right to take a deployment offline for maintenance, change a domain, change a host, or change any public URL with the same notice the source repository receives.

The “current canonical landing” and “current canonical studio” URLs are recorded indocs/product/public-claims.md and surfaced as a single canonical source (src/release/public-urls.ts in this repository).

Reference data is licensed by its publisher

Each reference pack and each upstream provider carries its own licence, recorded in the pack manifest and in Data & licences. Kingfisher redistributes data only where the licence permits, with the attribution the licence requires.Your use of a pack inherits the packs licence; if you want to redistribute a pack, read the licence, not this page.

Account, sync, telemetry

There is no Kingfisher account, no Sync, and no telemetry. The web build does not set cookies. See the Privacy page for the full statement.

Engine binaries

The native engines Kingfisher can install (Stockfish, Halogen, PlentyChess, Stormphrax, Viridithas, Lc0 and others) carry their own licences, recorded indocs/ENGINES.md and in the catalogue row inside the application.Native engines run with your user accounts permissions and are not sandboxed.You agree to that by installing one.

No professional advice

Kingfisher is a chess research tool, not a chess coach. The Training, Repertoire and Review workflows help you organise your study; they do not decide what to study, and they do not take responsibility for the result. Nothing the application shows is a substitute for a coach, a tournament, or the opponent across the board.

Changes to these terms

This page may be updated. Material changes will be listed in CHANGELOG.md. If a change affects a right or a warranty, the change will not be retroactive.

Contact

The maintainer can be reached through the public issue tracker atgithub.com/mardakurt/kingfisher/issues. For security, see the Security page.