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GLM-5.1

Z.ai · GLM

Z.ai's GLM-5.1, a 744B-parameter MoE open-weight model with strong autonomous coding and tool-use behavior.

Part of GLM family · Other versions: GLM-5.2 , GLM-5
Type
language
Context
203K tokens
Max Output
66K tokens
Status
current
Input
$1.4/1M tok
Output
$4.4/1M tok
API Access
Yes
License
MIT
chinese reasoning coding agentic open-weights long-context tool-use
Released April 2026 · Updated July 10, 2026

Overview

Freshness note: Model capabilities, limits, and pricing can change quickly. This profile is a point-in-time snapshot last verified on July 10, 2026.

GLM-5.1 is Z.ai’s post-training upgrade to GLM-5, the frontier model the company shipped on February 11, 2026. The 5.1 variant became available through Z.ai’s API on March 27, 2026, and as open weights on April 7, 2026. It keeps the GLM-5 base architecture (a 744B-parameter Mixture-of-Experts with 44B active per token) while substantially improving coding, tool use, and autonomous execution behavior. Z.ai claims the model can sustain coherent autonomous work for up to 8 hours on a single task, covering planning, execution, iteration, and delivery.

GLM-5.2 is now the family flagship, with a 1M context and newer sparse-attention architecture. GLM-5.1 remains an active 203K-context route for pinned integrations and teams that have already validated its behavior.

Capabilities

Z.ai’s release materials highlight a specific capability profile:

  • Strong autonomous coding behavior, including reported leadership on SWE-Bench Pro among open-source models at launch.
  • Long-horizon task execution with claimed sustained autonomy of up to 8 hours per task on coding workflows.
  • Improved tool calling and agent loop reliability over GLM-5.
  • Bilingual Chinese-English reasoning that remains a distinguishing strength of the GLM line.
  • Permissive MIT licensing on the open-weight release, enabling commercial use, fine-tuning, and redistribution without royalties.

Technical Details

Public anchors at this snapshot:

  • 744B total parameters, 44B active per token, Mixture-of-Experts with 256 experts (inherited from GLM-5).
  • 203K-token context window with up to 66K max output tokens.
  • Hosted API on Z.ai’s platform plus open weights on Hugging Face.
  • MIT license on the open-weight release.

GLM-5.1 is a post-training upgrade rather than a new base, so it shares GLM-5’s underlying architecture and most static specs.

Pricing & Access

Listed Z.ai API pricing (per 1M tokens):

  • Input: $1.40
  • Output: $4.40
  • Cache hit: $0.26 input

Z.ai raised its hosted pricing roughly 8% to 17% over the prior GLM-5 Turbo tier when 5.1 launched, so production cost models that referenced earlier GLM rates should be re-baselined.

Access options:

  • Z.ai (Zhipu AI) API
  • Open-weight downloads on Hugging Face under MIT
  • Third-party inference and gateway providers

Best Use Cases

Choose GLM-5.1 for:

  • Autonomous coding agents that need to run long, multi-step workflows without human-in-the-loop checkpoints.
  • Open-weight production deployments where MIT licensing simplifies legal review.
  • Bilingual Chinese-English assistant products where regional quality matters.
  • Tool-using agents and copilots at materially lower cost than US frontier alternatives.
  • Existing deployments that do not yet need GLM-5.2’s 1M context or architecture changes.

For teams that need US-based enterprise contracts, established cloud distribution, or governance defaults closer to Anthropic and OpenAI, GLM remains an additional option rather than a baseline replacement.

Comparisons

  • GLM-5.2 (Z.ai): Current 1M-context flagship with newer long-context infrastructure; 5.1 remains the established predecessor.
  • GLM-5 (Z.ai): Same base architecture; GLM-5.1 is the post-training upgrade with stronger coding and autonomous behavior.
  • DeepSeek V4 (DeepSeek): Closest open-weight peer for long-context production routes; GLM-5.1 leans more on autonomous coding behavior.