# Z.ai GLM 5.3 FlashX API

> GLM-5.3-FlashX is the high-speed tier of Z.ai's GLM-5.3-Flash, documented together with Flash and delivering inference speeds of up to 200 tokens per second. It shares Flash's native multimodal design and hybrid sparse-plus-linear attention, with image, video and file input, always-on reasoning, tool calling and structured output. Pick it over standard Flash for latency-sensitive coding agents, GUI and browser tasks, and interactive chat.

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

## Facts

- Provider: Z.ai
- Type: Language model
- Model ID: `z-ai/glm-5.3-flashx`
- Price: $0.37 per 1M input tokens, $1.25 per 1M output tokens
- 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-flashx",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ],
  "max_tokens": 2048
}'
```

## FAQ

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

Create a SandBase API key, then send requests with the model ID "z-ai/glm-5.3-flashx" 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 FlashX cost?

$0.37 per 1M input tokens and $1.25 per 1M output tokens, billed per request from your SandBase balance. Discounts, when available, are shown in the pricing on this page.

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

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

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

Z.ai GLM 5.3 FlashX 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 FlashX and the other models in the catalog; you do not need to sign up with Z.ai separately.