| Sep 14, 2025 | Gallagher | 0–1 | Koster | Round 5: Gallagher, Daniel GH - Koster, Chiel | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | |
| Sep 13, 2025 | Koster | 1–0 | Wang | Round 4: Koster, Chiel - Wang, Jake | Sicilian Defense: Kan Variation, Swiss Cheese Variation | |
| Sep 13, 2025 | Aydogdu | 1–0 | Koster | Round 3: Aydogdu, Cagatay - Koster, Chiel | English Opening: Symmetrical Variation, Fianchetto Variation | |
| Sep 12, 2025 | Seel | 1–0 | Koster | Round 1: Seel, Christian, Dr. - Koster, Chiel | Queen's Pawn Game: London System, with e6 | |
| Sep 12, 2025 | Koster | 1–0 | Jordan | Round 2: Koster, Chiel - Jordan, Felix | Neo-Grünfeld Defense: Classical Variation | |
| Jun 8, 2025 | Koster | ½–½ | Kurt | Round 5: Koster, Chiel - Kurt, Sascha | English Opening: King's English Variation, Three Knights System | |
| Jun 7, 2025 | Barzen | 1–0 | Koster | Round 3: Barzen, Pascal - Koster, Chiel | Sicilian Defense: Old Sicilian | |
| May 18, 2025 | Ritzerveld | ½–½ | Koster | Round 6: Ritzerveld, Noah - Koster, Chiel | Sicilian Defense: Lasker-Pelikan Variation | |
| May 18, 2025 | Koster | ½–½ | Kazarjan | Round 5: Koster, Chiel - Kazarjan, Gachatur | Tarrasch Defense: Classical Variation | |
| May 17, 2025 | Vennix | 0–1 | Koster | Round 3: Vennix, Tom - Koster, Chiel | English Opening: King's English Variation, Taimanov Variation | |
| May 17, 2025 | Koster | 1–0 | De Vries | Round 2: Koster, Chiel - De Vries, Emma | Neo-Grünfeld Defense: Ultra-Delayed Exchange Variation | |
| May 16, 2025 | Blijlevens | ½–½ | Koster | Round 1: Blijlevens, Pim - Koster, Chiel | Trompowsky Attack | |
| Jul 29, 2024 | Stillger | 0–1 | Koster | Round 6: Stillger, Bernhard - Koster, Chiel | King's Indian Attack | |
| Jul 27, 2024 | Koster | 1–0 | Smit | Round 5: Koster, Chiel - Smit, Manuel | English Opening: Anglo-Indian Defense, King's Indian Formation | |
| Jul 26, 2024 | Van Kuijk | ½–½ | Koster | Round 4: Van Kuijk, Vadim - Koster, Chiel | Sicilian Defense: Lasker-Pelikan Variation, Sveshnikov Variation, Chelyabinsk Variation | |
| Jul 25, 2024 | Koster | 0–1 | Shakhverdian | Round 3: Koster, Chiel - Shakhverdian, William | King's Indian Defense: Fianchetto Variation, Yugoslav Variation, Advance Line | |
| Jul 24, 2024 | Ritzerveld | ½–½ | Koster | Round 2: Ritzerveld, Noah - Koster, Chiel | French Defense: Rubinstein Variation, Blackburne Defense | |
| Jul 23, 2024 | Koster | ½–½ | Grooten | Round 1: Koster, Chiel - Grooten, Herman | Caro-Kann Defense | |
| Jun 2, 2024 | Koster | 0–1 | Baselmans | WLC Tournament 2024 A | Italian Game: Two Knights Defense, Modern Bishop's Opening | |
| Jun 2, 2024 | Coronel | 0–1 | Koster | WLC Tournament 2024 A | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation | |
| Jun 1, 2024 | Koster | 0–1 | Beerdsen | WLC Tournament 2024 A | Caro-Kann Defense | |
| Jun 1, 2024 | Koster | ½–½ | Kools | WLC Tournament 2024 A | English Opening: King's English Variation, Taimanov Variation | |
| Jun 1, 2024 | Matthijssen | 0–1 | Koster | WLC Tournament 2024 A | Sicilian Defense: Lasker-Pelikan Variation, Sveshnikov Variation, Chelyabinsk Variation | |
| May 31, 2024 | Van Happen | 0–1 | Koster | WLC Tournament 2024 A | Sicilian Defense: Lasker-Pelikan Variation, Sveshnikov Variation | |
| Aug 1, 2024 | Koster | ½–½ | Grooten | Round 9: Koster, Chiel - Grooten, Tommy | Sicilian Defense: Scheveningen Variation, Delayed Keres Attack | |
| Jul 31, 2024 | Zwirs | ½–½ | Koster | Round 8: Zwirs, Jasper - Koster, Chiel | Rapport-Jobava System | |
| Jul 30, 2024 | Koster | 0–1 | Buckels | Round 7: Koster, Chiel - Buckels, Valentin | Caro-Kann Defense | |
| May 7, 2023 | Koster | 1–0 | Sprangers | WLC Toernooi 2023 A | Sicilian Defense: Najdorf Variation, Adams Attack | |
| May 7, 2023 | Bollen | ½–½ | Koster | WLC Toernooi 2023 A | King's Indian Defense: Fianchetto Variation, Panno Variation | |
| May 6, 2023 | Koster | 1–0 | Baselmans | WLC Toernooi 2023 A | French Defense: Queen's Knight | |
| May 6, 2023 | Koes | 0–1 | Koster | WLC Toernooi 2023 A | Sicilian Defense: Wing Gambit | |
| May 6, 2023 | Beerdsen | 1–0 | Koster | WLC Toernooi 2023 A | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation, Gufeld Gambit | |
| May 5, 2023 | Koster | 1–0 | Messaoudi | WLC Toernooi 2023 A | ? | |
| — | Koster | ½–½ | Kools | WLC 2022 A | Sicilian Defense: Kan Variation, Polugaevsky Variation | |
| — | Koster | 1–0 | Van Helvoort | WLC 2022 A | Modern Defense | |
| — | Koster | ½–½ | Van Roon | WLC 2022 A | Sicilian Defense: Najdorf Variation, Adams Attack | |
| — | Roebers | ½–½ | Koster | WLC 2022 A | Sicilian Defense: Lasker-Pelikan Variation, Sveshnikov Variation, Novosibirsk Variation | |
| — | van der Valk | ½–½ | Koster | WLC 2022 A | English Opening: King's English Variation, Four Knights Variation, Fianchetto Line | |
| — | Slagboom | 0–1 | Koster | WLC 2022 A | Indian Defense: Anti-Nimzo-Indian | |
