# Z.ai GLM 5.3 Flash API

> GLM-5.3-Flash is the first native multimodal model in Z.ai's GLM-5 series, a 320B-parameter mixture-of-experts model with 18B active parameters that combines sparse and linear attention to cut long-context compute and KV cache. Vision is built into its coding loop, letting it inspect rendered interfaces and GUI feedback for frontend, game and computer-use work, and it also handles office documents and financial research. Z.ai reports it outperforms GLM-5.2; GLM-5.3-FlashX serves it at higher speed.

Source: https://www.sandbase.ai/models/z-ai/glm-5.3-flash
API reference: https://www.sandbase.ai/models/z-ai/glm-5.3-flash/docs

## Facts

- Provider: Z.ai
- Type: Language model
- Model ID: `z-ai/glm-5.3-flash`
- Price: $0.11 per 1M input tokens, $0.38 per 1M output tokens (25% off list price)
- Context window: 1M tokens, up to 131.1K output tokens
- Capabilities: chat, vision, reasoning, structured output, function calling
- Billing: pay per use from one SandBase balance; no provider account or subscription needed

## Call it

- Chat Completions API: `POST https://api.sandbase.ai/v1/chat/completions`

```bash
curl -X POST https://api.sandbase.ai/v1/chat/completions \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "z-ai/glm-5.3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ],
  "max_tokens": 2048
}'
```

## FAQ

### How do I call Z.ai GLM 5.3 Flash through SandBase?

Create a SandBase API key, then send requests with the model ID "z-ai/glm-5.3-flash" to Chat Completions API (/v1/chat/completions) at https://api.sandbase.ai. The request examples on this page show the exact payload.

### How much does Z.ai GLM 5.3 Flash cost?

$0.11 per 1M input tokens and $0.38 per 1M output tokens with the current 25% discount (list price $0.15 / $0.50), billed per request from your SandBase balance.

### What is the context window of Z.ai GLM 5.3 Flash?

1M tokens of context, with up to 131.1K output tokens per response.

### How does Z.ai GLM 5.3 Flash score on benchmarks?

Z.ai GLM 5.3 Flash scores 41.8 on the Artificial Analysis Intelligence Index (v4.3), ranking #18 of 83 models on SandBase; Coding Index 71.5, Agentic Index 50.9. Source: Artificial Analysis, measured as GLM 5.3 Flash.

### Which features does Z.ai GLM 5.3 Flash support?

Z.ai GLM 5.3 Flash supports vision (image input), reasoning, function calling, structured output. See Specifications above for the full list.

### Do I need a separate Z.ai account?

No. One SandBase API key and balance gives you access to Z.ai GLM 5.3 Flash and the other models in the catalog; you do not need to sign up with Z.ai separately.