Z.aiFastHigh

GLM 5.3 Flash

Z.ai's GLM 5.3 Flash served through the OpenRouter aggregator (listed 2026-08-26) - a low-cost native multimodal model (text, image, video input) for efficient coding and long-horizon agent tasks. Its hybrid sparse and linear attention keeps long-context behavior accurate across a 1.31M-token window. Billed at OpenRouter's actual usage cost.

279/929credits

input / output · per 1M tokens

1.31M-token context window (1M via the top provider), very large output budget

Very low cost - budget-tier input and output rates

Native multimodal input (text, image, video) with reasoning (reasoning_effort + parallel tool calls)

OpenAI-compatible API (chat completions) via /llm/openrouter/v1

Billed at OpenRouter's actual usage.cost - listed rates are estimates

Run it right now

Test this model instantly in the Console Playground — no code required

Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

llms.txtllms.txt ↗

Model Specifications

Context Window

1.3M

tokens

Max Output

944K

tokens

Training Cutoff

Not published

Compatible SDK

OpenAI

Capabilities

Vision

Function Calling

Streaming

JSON Mode

System Prompt

Token Pricing (per 1M tokens)

Token Type	Credits	USD Equivalent
Input Tokens	279	$0.19
Output Tokens	929	$0.62
Cached Tokens	55.74	$0.04

* 1,500 credits ≈ $1 (actual charges may vary based on usage)

Quick Start

curl -X POST "https://api.core.today/llm/openrouter/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "z-ai/glm-5.3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Summarize the attached report in 5 bullets."
    }
  ],
  "max_tokens": 1024
}'

Parameters

Parameter	Type	Required	Default	Description
`model`	string	Yes	-	Model ID in vendor/model form, e.g. "z-ai/glm-5.3-flash".
`messages`	array	Yes	-	Chat messages in OpenAI format (system/user/assistant roles).
`temperature`	number	No	0.7	Sampling temperature (0-2).
`max_tokens`	integer	No	2048	Maximum completion tokens.
`stream`	boolean	No	false	Stream the response as server-sent events.

Examples

Chat completion

OpenAI-compatible chat completion request via OpenRouter

curl -X POST "https://api.core.today/llm/openrouter/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "z-ai/glm-5.3-flash",
  "messages": [
    {
      "role": "user",
      "content": "Summarize the attached report in 5 bullets."
    }
  ],
  "max_tokens": 1024
}'

Tips & Best Practices

1Works with the OpenAI SDK - set base_url to https://ai.api.core.today/llm/openrouter/v1

2Charged at OpenRouter's usage.cost x 1,858 credits/USD - the listed rates are estimates and may lag OpenRouter price changes

3Accepts image and video input in OpenAI content-part format; use reasoning_effort to trade latency for depth, and step up to z-ai/glm-5.3 for the hardest engineering tasks