What is Z.ai: GLM 5.1's context window?

Z.ai: GLM 5.1 supports a context window of 200,000 tokens, allowing you to process large documents and maintain long conversations.

How to use Z.ai: GLM 5.1 API via Ofox?

Simply set your base URL to https://api.ofox.ai/v1 and use your Ofox API key. The API is OpenAI-compatible — just change the base URL and API key in your existing code.

Z.ai: GLM 5.1

Name: Z.ai: GLM 5.1
Brand: z-ai
Price: 1.4 USD
Availability: InStock

Chat

z-ai/glm-5.1

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GLM 5.1 is Z.ai's GLM-series chat model released on 2026-03-27, a newer iteration of the line aimed at general-purpose and agentic workloads. It supports reasoning, function calling (tool use), prompt caching, and web search, covering agentic loops that mix tool calls with retrieval. Context: 200K tokens, output: 128K. Available via OpenAI and Anthropic protocols through Ofox.

Context Window

200K

Max Output Tokens

128K

Released

2026-03-27

Capabilities

Function CallingReasoningPrompt CachingWeb Search

Available Providers

Z.aiAliyunAlibaba Cloud

Supported Protocols

openaianthropic

Providers

Alibaba Cloudprovider.type: "alicloud"

Input Tokens

$1.4/M

Output Tokens

$4.4/M

Cache Read

$0.26/M

Web Search

$0.01/R

Protocols

openai/v1/chat/completions

anthropic

Aliyunprovider.type: "aliyun"

Input Tokens

$1.4/M

Output Tokens

$4.4/M

Cache Read

$0.26/M

Cache Write

$1.5/M

Web Search

$0.01/R

Protocols

openai/v1/chat/completions

anthropic

Z.aiprovider.type: "zai"

Input Tokens

$1.4/M

Output Tokens

$4.4/M

Cache Read

$0.26/M

Web Search

$0.01/R

Protocols

openai/v1/chat/completions

anthropic

Playground

Open in OfoxChat

Code Examples

from openai import OpenAI

client = OpenAI(
    base_url="https://api.ofox.ai/v1",
    api_key="YOUR_OFOX_API_KEY",
)

response = client.chat.completions.create(
    model="z-ai/glm-5.1",
    messages=[
        {"role": "user", "content": "Hello!"}
    ],
)

print(response.choices[0].message.content)

Uptime & Status

Benchmarks

LMArena ↗Evaluated as glm-5.1

Z.ai: GLM 5.1 scores 1472 in the Overall category of the LMArena text leaderboard (style control), ranking #25 of 374 models based on 27,322 human preference votes (updated 2026-07-12).

Benchmark scores for glm-5.1 on LMArena
Category	Arena Score	95% CI	Rank	Votes
Overall	1472	1467–1477	#25 of 374	27,322
Hard Prompts	1494	1488–1500	#22 of 374	18,029
Coding	1522	1514–1529	#17 of 369	7,638
Math	1479	1463–1495	#18 of 362	1,432
Creative Writing	1454	1445–1464	#19 of 372	4,644
Instruction Following	1465	1458–1472	#21 of 374	9,253
Chinese	1518	1502–1534	#18 of 344	1,561

Source: LMArena · CC BY 4.0 · Updated 2026-07-12 · Methodology ↗ · Ranks compare models within each category of the LMArena text leaderboard (style control). Scores come from third-party human preference evaluations, not from OFOX.