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z-ai/glm-5-3

GLM 5.3

GLM-5.3 is a large-scale reasoning model from Z.ai, built for complex software engineering and long-horizon agent tasks. It supports text input and output with a 1M-token context window, and improves...

8/18/2026
1,048,576 tokens
Input: ¥250.18/M
Output: ¥786.28/M
Specifications

Modalities

Input
text
Output
text

Supported Parameters

include_reasoning
max_tokens
reasoning
reasoning_effort
response_format
temperature
tool_choice
tools
top_k
top_p

Max Output Tokens

131,072
Code Examples
curl https://api.fastmetal.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "glm-5.3",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

How GLM 5.3 actually answers

Real responses to our standard prompts, recorded on FastMetal.

Count the number of 'r's in 'strawberry'

Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.

# Counting 'r's in "strawberry" **Step 1: Spell out the word letter by letter.** s - t - r - a - w - b - e - r - r - y **Step 2: Go through each letter and mark the 'r's.** | Position | Letter | Is it 'r'? | |----------|--------|------------| | 1 | s | No | | 2 | t | No | | 3 | **r** | ✅ Yes (1st) | | 4 | a | No | | 5 | w | No | | 6 | b | No | | 7 | e | No | | 8 | **r** | ✅ Yes (2nd) | | 9 | **r** | ✅ Yes (3rd) | | 10 | y | No | **Step 3: Tally the results.** - 1st 'r' in "st**r**awberry" - 2nd 'r' in "strawbe**r**ry" - 3rd 'r' in "strawber**r**y" ## Answer: There are **3** 'r's in "strawberry." (Note: two of them appear together in the "rr" near the end, which is easy to miss when c…
5.8s response493 output tokens
Debug This Error

I'm getting the following error in my Node.js application: TypeError: Cannot read properties of undefined (reading 'map') at UserList (/app/components/UserList.js:12:25) at renderWithHooks (/app/node_modules/rea…

## What's happening The error means `users` is `undefined` when the component renders. `undefined` doesn't have a `.map()` method, so JavaScript throws a `TypeError`. Since destructured props that aren't passed default to `undefined`, something upstream isn't providing the value you expect. ## Common causes 1. **The parent doesn't pass the prop, or uses a different name:** ```jsx <UserList /> {/* missing users */} <UserList userList={users} /> {/* prop name mismatch */} ``` 2. **Async data hasn't loaded yet** — the component renders before an API call completes, and the initial value is `undefined`: ```jsx const [users, setUsers] = useState(); // undefin…
17.1s response1345 output tokens
Code Review

Please review the following Python function and suggest improvements for readability, performance, and best practices: def get_data(url, retries=3): import requests import time for i in range(retries):…

Here's a breakdown of the issues, followed by a refactored version. ## Readability - **Move imports to module level.** PEP 8 requires top-level imports; importing inside a function hides dependencies and adds overhead on every call (small, but pointless). - **`item["active"] == True`** → just `item.get("active")`. Comparing to `True` with `==` is flagged by PEP 8, and `.get()` avoids a `KeyError` if the key is missing. - **Use a list comprehension** instead of initializing a list and appending in a loop. - **Rename things.** `get_data` doesn't say what it does (`fetch_active_items`?), and `response` beats `r`. Use `_` for the unused loop counter. - **Magic numbers** (`2`, `10`) should be n…
75.0s response6434 output tokens

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Try GLM 5.3 right now

GLM 5.3 is available on FastMetal through one API key. Start in the browser, or call it from the OpenAI SDK.