Chinese AI lab Z.ai released GLM-5.2, an open-weights text model that now ranks as the leading model on independent benchmark standards, outperforming rivals on reasoning tasks.

What happened: Z.ai released GLM-5.2, a 753-billion-parameter text-only model, under an MIT license on June 16th. The model ranks #1 on the Artificial Analysis Intelligence Index v4.1 with a score of 51, ahead of MiniMax-M3 (44), DeepSeek V4 Pro (44), and Kimi K2.6 (43). It also ranks #2 on the Code Arena WebDev leaderboard, behind only Claude Fable 5.

Why it matters: GLM-5.2 achieves top-tier performance on major independent benchmarks while remaining available as open-weights software under a permissive license. This means researchers and businesses can deploy and modify it without licensing restrictions. The model's 1 million token context window (up from GLM-5.1's 200,000) allows it to process and work with substantially longer documents or conversations.

What to watch: The model generates substantially more output tokens per task than competitors—43k tokens per benchmark task, compared with 26k for GLM-5.1 and 24k for MiniMax-M3. On OpenRouter, input costs $1.40/million tokens and output costs $4.40/million tokens, making it cheaper than GPT-5.5 ($5/$30) and Claude Opus 4.5-4.8 ($5/$25).