GLM 5.3

Reviewed by Proof · Updated

Definition

GLM 5.3 is Z.ai's flagship open-weight coding and agent model, available on luv13 as luv13/glm-5.3.

Key facts

Model id

luv13/glm-5.3
luv13 price
$0.33 per 1M tokens, input and output
Availability
Available
Maker
Z.ai
Open weights
Yes
Modalities
  • Text
Context window
1M tokens (maker's published figure)
Released

Key takeaways

  • The luv13 model id is luv13/glm-5.3.
  • Made by Z.ai. The weights are open, under Z.ai's own glm-5.3 license.
  • Z.ai says it takes text input only.
  • Z.ai publishes a 1M-token context window. That's the maker's figure, not a luv13 limit.

Overview

GLM-5.3 is Z.ai's flagship model in the GLM-5 series. Z.ai built it on the same base model as GLM-5.2 and says every improvement came from post-training.

Z.ai positions it for complex software engineering and long-horizon agent tasks. It reports a 50% gain over GLM-5.2 on its in-house Z.ai Code Bench, and strong results on security work such as vulnerability discovery. Z.ai's documentation lists a maximum output of 128K tokens on its own platform.

The id comes from live GET https://api.luv13.ai/v1/models; every other fact comes from the maker's sources below. The context window is the maker's published figure, not a luv13 limit; luv13 hasn't published its own per-model limits.

Z.ai writes the name as GLM-5.3; luv13 lists it as GLM 5.3.

Price on luv13: see Pricing.

Examples

Set your key first: export LUV13_API_KEY=sk-luv13-... (see Keys and Accounts).

curl:

curl https://api.luv13.ai/v1/chat/completions \
  -H "Authorization: Bearer $LUV13_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "luv13/glm-5.3", "messages": [{"role": "user", "content": "Hello"}]}'

Python (pip install openai):

import os
from openai import OpenAI

client = OpenAI(base_url="https://api.luv13.ai/v1", api_key=os.environ["LUV13_API_KEY"])
reply = client.chat.completions.create(
    model="luv13/glm-5.3",
    messages=[{"role": "user", "content": "Hello"}],
)
print(reply.choices[0].message.content)

JavaScript (npm install openai, Node.js):

import OpenAI from "openai";

const client = new OpenAI({ baseURL: "https://api.luv13.ai/v1", apiKey: process.env.LUV13_API_KEY });
const reply = await client.chat.completions.create({
  model: "luv13/glm-5.3",
  messages: [{ role: "user", content: "Hello" }],
});
console.log(reply.choices[0].message.content);

Without a valid key, all three return HTTP 401 with "type": "invalid_auth" (checked on 2026-09-30). See Errors and Status Codes.

FAQ

What model id do I use on luv13? luv13/glm-5.3, exactly as GET /v1/models lists it. See Model IDs.

Who makes GLM 5.3? Z.ai.

Are the weights open? Yes. Z.ai released them under its custom glm-5.3 license; read it before commercial use.

Is the context window a luv13 limit? No. It's the maker's published figure. luv13 hasn't published its own per-model limits; see Limits.

How much does it cost on luv13? See Pricing.

Sources