Claude Opus 4.6 vs GLM 5.1

Choose Claude Opus 4.6 if you want…

• ✓Larger context window (1M)

Choose GLM 5.1 if you want…

• ✓Higher intelligence (Artificial Analysis index 51)
• ✓Faster output (~80.7 tokens/sec)
• ✓Lower price ($2.15 / 1M blended)

Claude Opus 4.6

Opus 4.6 is the model researchers and engineers reach for when the problem genuinely cannot be chunked — loading an entire codebase, a year's worth of literature, or a complex multi-part investigation into a single session of up to 750,000 words. It tops Terminal-Bench 2.0 among frontier models for agentic coding tasks and leads BrowseComp for hard-to-locate information retrieval, reflecting a design philosophy built around sustained, autonomous work rather than quick exchanges. Scientists have noted roughly double the accuracy on computational biology and structural chemistry tasks versus its predecessor. The tradeoff is speed: at 38.8 tokens per second, it feels noticeably slower than alternatives during interactive back-and-forth. The 1M-token window is also still in beta, and users report meaningful performance degradation well before hitting its ceiling. Best suited to high-stakes tasks where depth matters more than pace.

GLM 5.1

GLM-5.1 from Z.ai is built for one thing above all else: software engineering that runs on its own. A 754-billion parameter Mixture-of-Experts model, it tops the SWE-Bench Pro leaderboard at 58.4%, edging out both GPT-5.4 and Claude Opus 4.6 on real-world coding tasks. What sets it apart in practice is stamina — it can pursue a single engineering goal autonomously for up to eight hours, sustaining hundreds of iterations and thousands of tool calls without human intervention. Users consistently praise this long-horizon execution for agent-based workflows where other models stall. It also delivers fast responses, with a time-to-first-token of 1.33 seconds against a class median of 2.37 seconds. The honest trade-off: GLM-5.1 accepts text only, with no image input, making it a poor fit for visual debugging or UI-centric tasks. It also tends toward verbosity in practice, which can inflate token costs. For teams building autonomous coding pipelines, though, it earns its place at the top of the leaderboard.