GLM-5.1: First Open-Source Model to Top SWE-bench Pro (2026)

On April 7, 2026, Z.ai dropped GLM-5.1 — a 754-billion-parameter open-weight model that, for nine days, held the top spot on SWE-bench Pro with a score of 58.4%, beating GPT-5.4 (57.7%) and Claude Opus 4.6 (57.3%). It was the first time an open-sourc...