# GLM-5.3-FlashX

> GLM-5.3-FlashX is a high-speed Z.ai native multimodal model, designed for fast inference.

## Key facts

- Model author: Z.ai
- Input: $0.2857 per 1M tokens (starting price)
- Output: $1.00 per 1M tokens (starting price)
- Cached input: $0.075 per 1M tokens
- Context window: 1,000,000 tokens
- Maximum output: 128,000 tokens
- Input modalities: image, text, video
- Output modalities: text
- Capabilities: reasoning, tools, vision
- Released: 2026-09-18
- Model IDs: `jd/glm-5.3-flashx`, `z-ai/glm-5.3-flashx`
- Model page: https://www.realrelay.ai/model/z-ai/glm-5.3-flashx

## Overview

GLM-5.3-FlashX is a high-speed native multimodal model from Z.ai, built on a hybrid sparse and linear attention architecture. Z.ai positions it around fast inference, for interactive use where response time matters. It supports reasoning and tool calling, so it can drive agents that need quick turns between steps.

GLM-5.3-FlashX has a 1M-token context window and can generate up to 128K output tokens. It accepts text, image and video input and returns text output. It was released on September 18, 2026.

## Capabilities

GLM-5.3-FlashX supports reasoning, tool calling and visual understanding. Z.ai lists inference speed as its defining trait.

## Pricing

GLM-5.3-FlashX starts from $0.2857 per 1M input tokens and from $1.00 per 1M output tokens. Cache reads start from $0.075 per 1M tokens. These are starting prices and the rate can vary.

GLM-5.3-FlashX is available through RealRelay's OpenAI-compatible API.

## Use cases

Use GLM-5.3-FlashX for interactive multimodal assistants that answer questions about screenshots, images or video and need quick replies.

Its fast inference also helps coding and agent loops where every step waits on a model reply, and the 1M-token context window holds the accumulated history, so a long session does not need to be trimmed early.

## Call it

OpenAI-compatible chat completions:

```bash
curl https://www.realrelay.ai/v1/chat/completions \
  -H "Authorization: Bearer $REALRELAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "z-ai/glm-5.3-flashx", "messages": [{"role": "user", "content": "Hello"}]}'
```

## FAQ

### What is GLM-5.3-FlashX?

GLM-5.3-FlashX is a high-speed Z.ai native multimodal model, designed for fast inference.

### How much does GLM-5.3-FlashX cost?

GLM-5.3-FlashX starts from $0.2857 per 1M input tokens and from $1.00 per 1M output tokens, with cache reads from $0.075 per 1M tokens.

### What is the context window of GLM-5.3-FlashX?

GLM-5.3-FlashX has a 1M-token context window and can generate up to 128K output tokens.

### What inputs and outputs does GLM-5.3-FlashX support?

GLM-5.3-FlashX accepts text, image and video input and returns text output.

### Does GLM-5.3-FlashX support tool calling?

Yes. GLM-5.3-FlashX supports tool calling, along with reasoning and visual understanding.

### When was GLM-5.3-FlashX released?

GLM-5.3-FlashX was released on September 18, 2026.

### How do I call GLM-5.3-FlashX via the API?

Send requests to RealRelay's OpenAI-compatible API and use the model ID z-ai/glm-5.3-flashx.