GLM 5.3 Flash

Efficient multimodal coding, 1M context

Try GLM 5.3 Flash in the Workbench

Run this model interactively, tune parameters, and compare outputs.

Model ID: zai-org-glm-5-3-flash

GLM-5.3-Flash is a native multimodal model from Z AI built for efficient coding and long-horizon agent tasks. With 320 billion total parameters and just 18 billion active, it outperforms GLM-5.2 across benchmarks at a fraction of the cost while approaching Claude Opus 4.8 on coding and agentic tasks.

It is the first multimodal model in the GLM-5 series, combining sparse and linear attention in a hybrid architecture that cuts long-context serving costs. Reasoning is always on and cannot be disabled; the reasoning_effort parameter accepts low, high, and max, with max as the default. Weights are published under an MIT license.

Fine-tuning trains an adapter over attention while the routed experts stay frozen in 4 bits, so a fine tune of this model costs about what a far smaller one would.

Metric	Value
Parameter Count	320 billion
Active Parameter Count	18 billion
Mixture of Experts	Yes
Context Length	1,048,576 tokens
Max Output	131,072 tokens
Multilingual	Yes
Tool Use	Yes
Structured Outputs	Yes

Example request

Use the Workbench as a request builder: configure parameters for this model in the UI, then open the API tab to copy the exact cURL or Python call.

Minimal

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "zai-org-glm-5-3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ]
}'

Basic parameters

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "zai-org-glm-5-3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false
}'

All parameters

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "zai-org-glm-5-3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false,
  "top_p": 1.0
}'

Fetch model details

The models endpoint returns the full model object, including its json_request_schema.

curl -H "Authorization: Bearer $OXEN_API_KEY" https://hub.oxen.ai/api/ai/models/zai-org-glm-5-3-flash

Request parameters

This model follows the standard OpenAI chat completions request body. See the chat completions reference for the full parameter list.