GLM 5.3 via the ApexApi gateway
GLM 5.3 is the flagship of Z.AI's GLM-5.3 family, built for coding and long-running agent work with a 1M token context window. It always reasons before answering. Pick it over GLM 5.3 Flash when answer quality matters more than cost; it is text only. Call it through ApexApi's unified, OpenAI-compatible API with one `ak-` key, alongside every other model in the catalog. It supports a 1,000,000-token context window, tool / function calling, and streaming responses. Pricing is $1.68 input and $5.28 output per 1M tokens, billed pay-per-use from your credit balance with no subscription.
GLM 5.3 is served through ApexApi's unified, OpenAI-compatible API. One key, one format, with smart routing and automatic failover. Provider: Z.ai.
Why GLM 5.3
1,000,000-token context
Reason over long documents, codebases, and multi-turn history in a single request.
Tool & function calling
Structured outputs and tool orchestration for agentic and automation workloads.
OpenAI-compatible
Drop-in with any OpenAI SDK. Change the base URL and key, keep your code.
Specifications
- Modality
- chat
- Context window
- 1000K tokens
- Max output
- 24.6K tokens
- Streaming
- Yes
- Tool / function calling
- Yes
- Vision input
- —
GLM 5.3 pricing
- A million tokens in and a million out costs $6.96 here, all-in.
- For lighter work, GLM 4.7 Flash from the same maker costs 11.0× less — one string apart on the same key.
- It is one of 36 chat models here with a 1M-token context window.
Getting started with GLM 5.3
OpenAI-compatible. Point your client at ApexApi, swap your key, and call it. No new SDK to learn.
from openai import OpenAI
client = OpenAI(
base_url="https://api.apexapi.dev/v1",
api_key="<YOUR_APEXAPI_KEY>",
)
response = client.chat.completions.create(
model="zai/glm-5.3",
messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)GLM 5.3 use cases
What teams build with GLM 5.3 on ApexApi.
Agents & automation
Tool-using agents that orchestrate multi-step workflows and call APIs.
Coding assistants
Code generation, refactoring, reviews, and multi-file reasoning.
RAG & knowledge apps
Summarization and long-document Q&A grounded in your own data.
GLM 5.3 vs other models
How it compares, and on ApexApi you can switch between any of them with a single string change, same key, same endpoint.
GLM 5.3 vs Claude Opus 4.7
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Learn more about Gemini 3.1 Pro Preview API →GLM 5.3 API: FAQ
How do I call GLM 5.3 through ApexApi?
Create an ApexApi key, point your client at https://api.apexapi.dev/v1, and POST to /v1/chat/completions with the model set to `zai/glm-5.3`. The API is OpenAI-compatible, so an existing OpenAI SDK works once you change the base URL and key.
How much does GLM 5.3 cost on ApexApi?
$1.68 per million input tokens and $5.28 per million output tokens, all-in with no separate platform fee. You buy credits and pay per call, with no subscription or minimum.
What is the context window for GLM 5.3?
1,000,000 tokens. It can return up to 24,576 tokens in a single response.
Does GLM 5.3 support tool calling and image input?
GLM 5.3 supports tool / function calling and streaming responses, and it does not support image (vision) input.
What should I use instead of GLM 5.3?
From the same maker, GLM 4.7 costs less for lighter work. Switching is one string: it runs on the same endpoint and the same key, so there is nothing to re-integrate.
Ready to build with GLM 5.3?
One API key. Every major AI model. Pay only for what you use.
Try GLM 5.3, pay as you go from $5