Introduction
Jonathan Westerberg, known online as jonathanwesterberg, is a FIDE Grandmaster whose online career reads like a love letter to fast chess. He has never met a bullet game he didn't like, and his statistics suggest he may be part clock.
Early Days and Rise
Jonathan's chess footprint dates back to 2008, when he was grinding Daily games around the 1500-1800 range. By 2013 he had transformed into a proper Blitz force, climbing through the 2200s and 2300s before breaking into elite territory around 2018. His rating graph shows a steady upward climb, punctuated by volcanic bursts of activity.
His workload in the mid-2020s is staggering. The data records 995 Bullet games in August 2025 alone, along with hundreds more in nearly every month. He is less a player and more a one-man distributed denial of service against the chess servers.
Style and Openings
Jonathan is a stubborn, resourceful competitor. With an early resignation rate of just 0.41%, he rarely folds early;; instead, he steers games toward endgames, where he outplays opponents at a remarkable rate. His comeback rate of 87.58% proves that even when he drops a piece, the game is far from over.
His opening repertoire revolves around the Sicilian Defense in all its forms, particularly the Closed Sicilian, and the solid Caro-Kann Defense. He also happily plays offbeat tries like the Amar Gambit and the Four Knights Game, proving that a grandmaster can still have fun at the board.
Rivalries
No profile of Jonathan would be complete without his fiercest online rival, Emil Jonsson. They have crossed swords 295 times, with Jonathan owning a dominant 253-32 record. If gnarpsk ever logs off, Jonathan is probably still in the queue waiting for game 296.
By the Numbers
- Longest winning streak of 22 games, and a longest losing streak of just 8.
- More than 2,000 Blitz wins and 2,700 Bullet wins, with win rates comfortably above 60%.
- Peak Bullet rating: 2950 (2026-03-16).
- Peak Blitz rating: 2871 (2026-01-24).
- Best time of day to face him? 08:00, when his win rate reportedly jumps to 75%. Avoid.
- Low tilt factor of 8, meaning losses rarely snowball into disaster.