GLM 5.3 Flash vs Grok 4.5
Pricing, context window and real answers (August 2026)
GLM 5.3 Flash (Z.ai) and Grok 4.5 (xAI), compared as you can actually call them on FastMetal. Both are served from the same OpenAI-compatible endpoint and API key; switching is a change to the model string.
Specs and pricing
 GLM 5.3 Flash |  Grok 4.5 | |
|---|---|---|
| Provider | Z.ai | xAI |
| Input (per 1M tokens) | ¥13.19 | ¥357.4 |
| Output (per 1M tokens) | ¥43.98 | ¥1,072.2 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥35 | ¥894 |
| Context window | 1,310,720 tokens | 500,000 tokens |
| Release date | 8/26/2026 | 7/8/2026 |
| Input modalities | text, image, video | text, image, file |
| Arena · overall | #38 · ELO 1,469 | #36 · ELO 1,470 |
| Arena · Japanese | Unranked | #39 · ELO 1,441 |
| Arena · coding | #11 · ELO 1,531 | #21 · ELO 1,523 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GLM 5.3 Flash: ¥43.98 per 1M output tokens, 96% less than Grok 4.5.
- On the Overall arena board, Grok 4.5 ranks higher (#36; GLM 5.3 Flash is #38).
- On the Coding arena board, GLM 5.3 Flash ranks higher (#11; Grok 4.5 is #21).
- For long documents, GLM 5.3 Flash: a 1,310,720-token context window against 500,000 for Grok 4.5.
- If in doubt, try both on the same key. Switching is a change to the model string, and each is billed at its own rate.
Real answers to the same prompts
Exactly what the FastMetal gateway returned, side by side. Not benchmark scores: actual output.
Count the number of 'r's in 'strawberry'
Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.
GLM 5.3 Flash
# Counting 'r's in 'strawberry'
**Step 1: Write out the word letter by letter**
s - t - r - a - w - b - e - r - r - y
**Step 2: Check each letter one at a time**
| Position | Letter | Is it 'r'? |
|----------|--------|-----------|
| 1 | s | No |
| 2 | t | No |
| 3 | r | **Yes! (1)** |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | r | **Yes! (2)** |
| 9 | r | **Yes! (3)** |
| 10 | y | No |
**Step 3: Add up the matches**
The 'r's appear at positions 3, 8, and 9.
## Answer: There are **3** 'r's in "strawberry" 🍓
7.2s449 output tokens
Grok 4.5
The word "strawberry" is spelled as follows:
**s-t-r-a-w-b-e-r-r-y**
- Position 1: **s**
- Position 2: **t**
- Position 3: **r** ← (1st "r")
- Position 4: **a**
- Position 5: **w**
- Position 6: **b**
- Position 7: **e**
- Position 8: **r** ← (2nd "r")
- Position 9: **r** ← (3rd "r")
- Position 10: **y**
There are **3** occurrences of the letter "r".
6.5s350 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…
GLM 5.3 Flash
## What's happening
The error means the `users` prop is `undefined` at the time `UserList` renders. Since you can't call `.map()` on `undefined`, JavaScript throws the TypeError.
This usually happens for one of these reasons:
1. **The parent isn't passing the prop** — rendering `<UserList />` without `users`, or with a typo'd prop name like `user={users}`.
2. **Data hasn't loaded yet** — the parent fetches data asynchronously and its state starts as `undefined`:
```jsx
const [users, setUsers] = useState(); // undefined until fetch resolves!
return <UserList users={users} />;
```
3. **API response shape mismatch** — the array is nested, e.g., you need `response.data.users` inst…
31.3s1639 output tokens
Grok 4.5
The error occurs because `users` is `undefined` when the component renders, so calling `.map()` on it fails.
This commonly happens when:
- The parent component doesn’t pass a `users` prop at all
- The data is loaded asynchronously and is still `undefined` on the first render
- The prop is accidentally set to `undefined`/`null` instead of an array
### Fixes
**1. Default to an empty array (simplest)**
```js
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={user.id}>{user.name}</li>
))}
</ul>
);
}
```
**2. Optional chaining (also fine)**
```js
function UserList({ users }) {
return (
<ul>
{users?.map(user => (…
7.9s507 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):…
GLM 5.3 Flash
Solid foundation — you're already passing an explicit `timeout` and implementing retries, which many people skip. Here's a breakdown by category:
## Correctness & robustness (most important)
- **Bare `except:`** catches *everything*, including `KeyboardInterrupt` and `SystemExit`, and silently discards the error. Catch specific exceptions: `requests.RequestException` for network issues, `ValueError` for invalid JSON.
- **Retrying non-retryable failures**: a 401/403/404 will never succeed on retry, so you're sleeping 6 seconds for nothing. Only retry transient errors (5xx, 429, timeouts/connection errors).
- **`item["active"]` raises `KeyError`** on malformed data. Use `item.get("active")`…
116.1s6185 output tokens
Grok 4.5
## Code Review: `get_data`
### Issues
| Area | Problem |
|------|---------|
| **Imports** | `requests` / `time` inside the function — re-imported on every call; belong at module level |
| **Exceptions** | Bare `except:` swallows `KeyboardInterrupt`, `SystemExit`, and hides bugs |
| **Boolean check** | `item["active"] == True` is unidiomatic; truthiness is enough |
| **Loop** | Manual `for` + `append` can be a list comprehension |
| **Retries** | Sleeps on non-200 but never logs or distinguishes failure modes; unused loop variable `i` |
| **Robustness** | No guard for non-list JSON, missing keys (`KeyError`), or invalid JSON |
| **API** | Magic numbers (`timeout=10`, `sleep=2`); no docstrin…
25.3s1363 output tokens
Frequently asked questions
- Which is cheaper, GLM 5.3 Flash or Grok 4.5?
- Per 1M output tokens, GLM 5.3 Flash is ¥43.98 and Grok 4.5 is ¥1,072.2 on FastMetal (yen, before tax), so GLM 5.3 Flash is cheaper.
- How do the context windows of GLM 5.3 Flash and Grok 4.5 compare?
- GLM 5.3 Flash takes 1,310,720 tokens; Grok 4.5 takes 500,000.
- Which ranks higher, GLM 5.3 Flash or Grok 4.5?
- GLM 5.3 Flash ranks higher on the public arena (GLM 5.3 Flash #38, Grok 4.5 #39). Ranks move as the leaderboard updates.
- Can I use GLM 5.3 Flash and Grok 4.5 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "glm-5.3-flash" or "grok-4.5" as the model. Each is billed at its own rate from the same prepaid balance.
Try both on one API key
Create an account and add credit to call GLM 5.3 Flash and Grok 4.5 from the browser chat and the API. No monthly fee.