Z.aiPartner-hosted · no ZDR

GLM 5.3 Flash

Name: GLM 5.3 Flash
Brand: Z.ai
Price: 0.2 USD

GLM-5.3-Flash is Z.ai's first natively multimodal GLM-5 model (MIT licence, August 2026). Despite the name it is a large mixture-of-experts network — 320B parameters, 18B active per token — built for coding and long-horizon agent work over long context at low serving cost. Reasoning effort is selectable (low, high, max), and it reads images alongside text. The developer declares English and Chinese; test other languages on your own material. It is served by a third-party inference provider through our partner, not on Heabsy hardware: the same key and the same invoice, but no zero data retention, and the request may be processed outside the EEA.

model id: glm-5.3-flash

from openai import OpenAI client = OpenAI(    api_key="hb-...",    base_url="https://api.heabsy.com/v1",) r = client.chat.completions.create(    model="glm-5.3-flash",    messages=[{"role": "user", "content": "Hello"}],)print(r.choices[0].message.content)

curl https://api.heabsy.com/v1/chat/completions \  -H "Authorization: Bearer $HEABSY_API_KEY" \  -H "Content-Type: application/json" \  -d '{    "model": "glm-5.3-flash",    "messages": [{"role": "user", "content": "Hello"}]  }'

import OpenAI from "openai"; const client = new OpenAI({  apiKey: process.env.HEABSY_API_KEY,  baseURL: "https://api.heabsy.com/v1",}); const r = await client.chat.completions.create({  model: "glm-5.3-flash",  messages: [{ role: "user", content: "Hello" }],});console.log(r.choices[0].message.content);

Context

1M tokens

Serving

Partner provider · no ZDR

Tool calling

Reasoning

Structured output

Vision

Input

$0.20/ 1M

Cached input

$0.0375/ 1M

Output

$0.60/ 1M

Price list, updated 10 October 2026. No minimum spend, no subscription.

About the model

Developer: Z.ai
Released: August 2026
Licence: MIT
Architecture: mixture of experts · 320B parameters, 18B active per token
Input: text, images
Reasoning: selectable effort
Languages named by the developer: English, Chinese

Source: the developer's model card, as of 17 September 2026.

Licence: what it means for your company

MIT. A permissive open-source licence: you may use, modify and sell products built on the model, including commercially; when you redistribute the weights, the licence and copyright notices go with them.

A summary of the licence, not legal advice.

Technical details

Context window: 1M tokens
Max output: 131,072 tokens
Throughput limit: —
Tokenizer: Other
Streaming: yes
Open weights: —

Supported parameters

max_tokens: 1 … 131072

Partner-hosted: same key and invoice, no ZDR

This model is served by a third-party inference provider through our partner, not on Heabsy hardware. You keep one key and one invoice from an EU company, but there is no zero data retention: the provider handles the request under its own policy, and processing may take place outside the EEA. For personal or regulated data, use a model on Heabsy hardware.

Questions about this model

›Where is GLM 5.3 Flash computed?

At a third-party inference provider that serves this model through our partner, outside our own infrastructure. Where exactly the request is computed is not fixed and may be outside the EEA. The contract and the invoice stay with our EU company.

›Does GLM 5.3 Flash store prompts and completions?

There is no zero-data-retention guarantee for this model: the request goes to a third-party provider, which handles it under its own policy and may keep logs. For personal or regulated data, use a model on Heabsy hardware.

›How large is the GLM 5.3 Flash context window?

1M tokens, with up to 131,072 tokens of output.

›What does GLM 5.3 Flash cost?

$0.20 per million input tokens and $0.60 per million output tokens. No minimum spend and no subscription; the same price list covers the API and the invoice.

›Is there a throughput limit on GLM 5.3 Flash?

The catalog does not report a throughput limit for this model.

›Which languages does GLM 5.3 Flash support?

The developer names English, Chinese. Languages not on that list may still work, but they are not claimed — test on your own material first.

›Under which licence is GLM 5.3 Flash released?

›Can reasoning be switched off in GLM 5.3 Flash?

The developer lets you choose how much the model reasons; the card does not document turning reasoning off completely.