GLM 5.3 Flash

• GPQA DiamondVery hard multiple-choice questions in biology, physics and chemistry, written by PhD experts. Random guessing scores 25%.90.2%#31 of 116
• AIME mathCompetition-level math problems in the style of the American Invitational Mathematics Examination. Share solved.93.9%#32 of 112
• FrontierMathOriginal, unpublished math problems written by professional mathematicians, from advanced to research level. Share solved.55.8%#36 of 73

Benchmark data: Epoch AI, licensed CC BY 4.0

Companies that serve this model through an API: 33. Prices per million tokens, cheapest first.

Availability and prices come from OpenRouter’s public API and are refreshed daily. Uptime is the share of successful requests over the last 24 hours. Some providers run a compressed version of open models (fp8, int4), which is cheaper but can be slightly less accurate.

Call GLM 5.3 Flash through OpenRouter’s OpenAI-compatible API: create a key on openrouter.ai, then run one of these examples.

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "z-ai/glm-5.3-flash", "messages": [{"role": "user", "content": "Hello! What can you do?"}]}'

import os
from openai import OpenAI

client = OpenAI(base_url="https://openrouter.ai/api/v1", api_key=os.environ["OPENROUTER_API_KEY"])
reply = client.chat.completions.create(
    model="z-ai/glm-5.3-flash",
    messages=[{"role": "user", "content": "Hello! What can you do?"}],
)
print(reply.choices[0].message.content)

import OpenAI from "openai";

const client = new OpenAI({ baseURL: "https://openrouter.ai/api/v1", apiKey: process.env.OPENROUTER_API_KEY });
const reply = await client.chat.completions.create({
  model: "z-ai/glm-5.3-flash",
  messages: [{ role: "user", content: "Hello! What can you do?" }],
});
console.log(reply.choices[0].message.content);

The same code works with every model on this site: only the model ID changes. Many labs also offer their own API and SDK.

• 1,000 chat replies

  ≈ 500 tokens in, 300 out each
  $0.225
• Summarise a 100-page document

  ≈ 50,000 tokens in, 1,000 out
  $0.008
• An app with 10,000 requests a day for a month

  ≈ 1,000 tokens in, 400 out each
  $105

Cost calculator →

• Simon WillisonSep 29, 2026

  Quoting Anthropic Frontier Red Team

• ABC TecnologíaSep 18, 2026es

  ¿Quién puede permitirse frenar la IA?: el miedo a la extinción como estrategia de mercado

How much does GLM 5.3 Flash cost?

GLM 5.3 Flash costs $0.15 per million input tokens and $0.50 per million output tokens through the API. For example, 1,000 chat replies of about 500 tokens in and 300 out cost around $0.225.

What is the context window of GLM 5.3 Flash?

GLM 5.3 Flash can read up to 1,048,576 tokens in one request, about 1,966 pages of text. It can write up to 943,717 tokens in a single answer.

Is GLM 5.3 Flash open source?

Yes. Its weights are published (zai-org/GLM-5.3-Flash), so you can download it and run it on your own hardware, or use it through one of 33 API providers.

Who makes GLM 5.3 Flash?

GLM 5.3 Flash is made by Z.ai (Zhipu). It became available through the API on August 26, 2026.

How good is GLM 5.3 Flash?

GLM 5.3 Flash has an overall index of 151.9 in Epoch AI’s independent tests, ranking #38 of 136 models we track.

Can GLM 5.3 Flash read images?

Yes. Besides text, it accepts images and video as input.

What are the alternatives to GLM 5.3 Flash?

Models with a similar price from other companies include Perceptron Mk1.5, Qwen3.8 Omni Flash and MiMo-V2.6-Flash. You can compare them side by side on this page.