GLM-5.3 Flash

GLM-5.3 Flash is a faster sibling of GLM-5.3, served on Sarvam infrastructure as an open-weight model. It accepts text and images and has a 1,048,576-token context window.

At a glance

Key capabilities

Quickstart

from sarvamai import SarvamAI
client = SarvamAI(api_subscription_key="YOUR_SARVAM_API_KEY")
response = client.chat.completions_v2(
    model="glm5.3-flash",
    messages=[
        {
            "role": "user",
            "content": "Write a Python function that checks whether a string is a palindrome.",
        }
    ],
    max_tokens=2000,
)
print(response.choices[0].message.content)

Supported parameters

model: "glm5.3-flash" on Chat Completion V2 and Responses. Full request/response schemas live on those API reference pages; this table covers what’s actually accepted for this model.

Reasoning

GLM-5.3 Flash reasons by default, at high effort. The two APIs accept different values:

Read the reasoning trace from choices[].message.reasoning_content on chat. On Responses, output starts with a reasoning item; read its content[0].text (summary is empty, unlike GLM-5.3). Reasoning tokens are billed as output tokens and count against max_tokens / max_output_tokens.

Image input

Send images as base64 data URIs in an image_url content part on chat, or an input_image part on Responses.

import base64
with open("chart.png", "rb") as f:
    data_uri = "data:image/png;base64," + base64.b64encode(f.read()).decode()
response = client.chat.completions_v2(
    model="glm5.3-flash",
    messages=[
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "Summarise this chart."},
                {"type": "image_url", "image_url": {"url": data_uri}},
            ],
        }
    ],
    max_tokens=2000,
)

How it differs from GLM-5.3

Known limitations

• Reasoning and the final answer share the max_tokens / max_output_tokens budget.
• Set max_tokens explicitly. When it’s omitted, generation isn’t capped at a small default and long answers can run to tens of thousands of tokens.

Limits and errors