GLM-5.3-Flash API

Zhipu's cost-efficient, natively multimodal Flash model in the GLM-5 family -- 320B total / 18B active parameters, MIT-licensed, 1M-token context. Formerly the stealth "Ox Alpha" model.

Modalities: Text, Image, VideoText
In / Out price: $0.15/$0.5per 1M
Context window: 1.05M tokens
Released: Aug 26, 2026

GLM-5.3-Flash overview

GLM-5.3-Flash by Zhipu AI

Meet GLM-5.3-Flash -- Zhipu's first natively multimodal GLM-5 model, formerly known as Ox Alpha.

GLM-5.3-Flash specs

Model ID: z-ai/glm-5.3-flash
Developer: Zhipu AI
Context window: 1,048,576 tokens
Max output: 131,072 tokens
Input: Text, Image, Video
Output: Text
API: OpenAI-compatible, base URL https://api.aimlapi.com/v1

What Is GLM-5.3-Flash API?

GLM-5.3-Flash is Zhipu AI's cost-efficient, natively multimodal model in the GLM-5 family, a 320-billion-parameter Mixture-of-Experts model with 18 billion active parameters, released under the MIT license. It's the model that spent a week topping usage charts anonymously under the stealth codename "Ox Alpha," now confirmed and generally available.

Technical Reference

Developer	Zhipu AI
Model ID	z-ai/glm-5.3-flash
Release Date	August 26, 2026
Context Window	1,048,576 tokens (~1M)
Max Output Tokens	131,072
Modalities	Text, image, video (input) → Text (output)
Capabilities	Reasoning, streaming, structured (JSON schema) output, tool/function calling

What GLM-5.3-Flash Brings to the Table

Natively multimodal
Unlike the text-only GLM-5.3, Flash accepts text, image, and video input, making it a drop-in choice for agentic workloads that need to reason over more than plain text.

MoE efficiency
Only 18B of the model's 320B parameters activate per token, which keeps inference fast and cheap without sacrificing the capability of a much larger model.

Open weights, MIT license
Weights are available on Hugging Face under a permissive MIT license, so the model can also be self-hosted.

1M-token context window
At just over 1,000,000 tokens, GLM-5.3-Flash can hold large documents, long conversation histories, or sizeable codebases in a single request.

Where GLM-5.3-Flash Makes the Most Sense

High-volume agentic workloads
Its MoE efficiency and low price make it a practical default for agents that need to run at scale without the cost of a full flagship model.

Multimodal reasoning tasks
Native image and video input support means it can be used directly for tasks a text-only model can't handle.

Long-document and long-conversation reasoning
The 1M-token window processes long reports, transcripts, or multi-file context in one pass.

Use cases

GLM-5.3-Flash is documented as suited to multimodal assistants and agents, including visual question answering, multi-image reasoning, document and screenshot understanding, coding and tool-using agents, and long-context document intelligence.

It is also documented for coding, reasoning, agentic workflows, long-context text processing, and image or video understanding.

Another documented use is high-volume coding and visual coding/front-end work, including self-checking rendered outputs and iterating on interfaces.

It is further described as fitting browser and GUI workflows, including computer-use tasks and other visual software workflows.

Capabilities

Reasoning
Streaming
Structured outputs
Function calling

GLM-5.3-Flash benchmarks by Artificial Analysis

See how GLM-5.3-Flash compares in intelligence, generation speed, cost per task and latency. Data retrieved Nov 3, 2026.

Intelligence#26 / 5027.8Index v5.0 Speed#144 / 21974.4Output tokens / second Cost per task#18 / 44$0.58USD / benchmark task Latency#113 / 2161.55Seconds to first token

Benchmark results

Compare 13 models available on AI/ML API across 5 independent benchmarks.

Humanity's Last Exam

Expert-written questions across academic subjects.

GLM-5.3-Flash API pricing

GLM-5.3-Flash pricing in US dollars
Usage	Price	Unit
Input	$0.15	1M tokens
Output	$0.5	1M tokens
Cached input	$0.03	1M tokens

Prices from the AI/ML API price list, checked on Nov 4, 2026.

GLM-5.3-Flash vs other models: token prices

AI/ML API input and output rates for 5 models, per million tokens.

AI/ML API model prices in USD per million tokens
Model	Input	Output
GLM-5.3-Flash	$0.15	$0.5
GLM 5.3 FlashX	$0.37	$1.25
GLM-5.3	$1.4	$4.4
GLM 5.2	$1.4	$4.4
GLM 5.2 Fast Preview	$3.5	$11

How to use the GLM-5.3-Flash API

View docs

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "z-ai/glm-5.3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "z-ai/glm-5.3-flash",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "z-ai/glm-5.3-flash",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

GLM-5.3-Flash FAQ

What is the context window of GLM-5.3-Flash?

GLM-5.3-Flash has a 1,048,576 tokens context window and can return up to 131,072 tokens.

What inputs and outputs does GLM-5.3-Flash support?

GLM-5.3-Flash takes image, text, video as input and returns text.

What is the model ID for GLM-5.3-Flash?

Use z-ai/glm-5.3-flash as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

When was GLM-5.3-Flash released?

GLM-5.3-Flash became available on August 26, 2026.

How much does GLM-5.3-Flash cost?

GLM-5.3-Flash costs $0.15 input and $0.5 output per 1M tokens on AI/ML API, billed as you go with no subscription.

Does GLM-5.3-Flash support streaming?

Yes, GLM-5.3-Flash can stream responses as they are generated.

Can GLM-5.3-Flash read images?

Yes, GLM-5.3-Flash accepts image input alongside text.

Who created GLM-5.3-Flash?

GLM-5.3-Flash was built by Zhipu AI.

Start building with GLM-5.3-Flash

Get API key

GLM-5.3-Flash API

z-ai/glm-5.3-flash

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "z-ai/glm-5.3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "z-ai/glm-5.3-flash",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "z-ai/glm-5.3-flash",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

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GLM-5.3-Flash API

GLM-5.3-Flash overview

GLM-5.3-Flash by Zhipu AI

GLM-5.3-Flash specs

What Is GLM-5.3-Flash API?

Technical Reference

What GLM-5.3-Flash Brings to the Table

Where GLM-5.3-Flash Makes the Most Sense

Use cases

Capabilities

GLM-5.3-Flash benchmarks by Artificial Analysis

Intelligence

Speed

Cost per task

Benchmark results

Humanity's Last Exam

GPQA Diamond

Terminal-Bench 4.0

AA-LCR

SciCode

GLM-5.3-Flash API pricing

GLM-5.3-Flash vs other models: token prices

How to use the GLM-5.3-Flash API

Build with your agent

1Get your API key

2Make your first request

GLM-5.3-Flash FAQ

Start building with GLM-5.3-Flash

GLM-5.3-Flash API

Build with your agent

1Get your API key

2Make your first request

GLM-5.3-Flash API

GLM-5.3-Flash overview

GLM-5.3-Flash by Zhipu AI

GLM-5.3-Flash specs

What Is GLM-5.3-Flash API?

Technical Reference

What GLM-5.3-Flash Brings to the Table

Where GLM-5.3-Flash Makes the Most Sense

Use cases

Capabilities

Intelligence

Speed

Cost per task

Benchmark results

Humanity's Last Exam

GPQA Diamond

Terminal-Bench 4.0

AA-LCR

SciCode

GLM-5.3-Flash API pricing

GLM-5.3-Flash vs other models: token prices

How to use the GLM-5.3-Flash API

Build with your agent

1Get your API key

2Make your first request

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GLM-5.3-Flash FAQ

Start building with GLM-5.3-Flash