Claude Opus 5 vs Qwen3.8 27B
Pricing, context window and real answers (August 2026)
Claude Opus 5 (Anthropic) and Qwen3.8 27B (Qwen), 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
 Claude Opus 5 |  Qwen3.8 27B | |
|---|---|---|
| Provider | Anthropic | Qwen |
| Input (per 1M tokens) | ¥893.5 | ¥80.41 |
| Output (per 1M tokens) | ¥4,467.5 | ¥571.84 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥3,127 | ¥366 |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Release date | 7/24/2026 | 8/14/2026 |
| Input modalities | text, image, file | text, image, video |
| Arena · overall | #7 · ELO 1,492 | #87 · ELO 1,436 |
| Arena · Japanese | #8 · ELO 1,495 | Unranked |
| Arena · coding | #8 · ELO 1,533 | #67 · ELO 1,498 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Qwen3.8 27B: ¥571.84 per 1M output tokens, 87% less than Claude Opus 5.
- On the Overall arena board, Claude Opus 5 ranks higher (#7; Qwen3.8 27B is #87).
- On the Coding arena board, Claude Opus 5 ranks higher (#8; Qwen3.8 27B is #67).
- 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.
Claude Opus 5
## Counting the 'r's in "strawberry"
**Step 1: Break the word into individual letters**
| Position | Letter |
|----------|--------|
| 1 | s |
| 2 | t |
| 3 | **r** |
| 4 | a |
| 5 | w |
| 6 | b |
| 7 | e |
| 8 | **r** |
| 9 | **r** |
| 10 | y |
**Step 2: Identify each occurrence of 'r'**
- Position 3: the 'r' in the "str-" beginning
- Position 8: the first 'r' in the "-rry" ending
- Position 9: the second 'r' in the "-rry" ending
**Step 3: Tally them up**
3 + 8 + 9 → that's **3 occurrences**.
## Answer: 3
The tricky part is that "strawberry" contains a *double* 'r' near the end ("berry"), which is easy to skim over as a single letter. Splitting the word into "straw" (1 'r') + "berry"…
7.1s466 output tokens
Qwen3.8 27B
The word is: **strawberry**
Break it into letters:
1. s
2. t
3. r
4. a
5. w
6. b
7. e
8. r
9. r
10. y
Now count the **r**’s:
- 3rd letter: **r**
- 8th letter: **r**
- 9th letter: **r**
So, there are **3** r’s in **strawberry**.
3.6s239 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…
Claude Opus 5
## What's happening
The error means `users` is `undefined` when `UserList` renders — so calling `.map()` on it throws. React isn't the problem; the prop simply isn't there yet (or ever).
The three most common causes:
1. **The parent isn't passing the prop** (or passes it under a different name / typo):
```jsx
<UserList /> // users is undefined
<UserList user={data} /> // wrong name
```
2. **The data is fetched asynchronously**, and the first render happens before it arrives:
```jsx
const [users, setUsers] = useState(); // undefined on first render!
useEffect(() => { fetch('/api/users').then(r => r.json()).then(setUsers); }, []);
return <UserList user…
15.1s1191 output tokens
Qwen3.8 27B
The error means that `users` is `undefined` when `UserList` renders:
```jsx
{users.map(...)}
```
JavaScript cannot call `.map()` on `undefined`.
For example, this would cause the error:
```jsx
<UserList />
```
because `users` is not being passed in.
## Simple fix: give `users` a default value
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
Now if `users` is not passed in, it defaults to an empty array.
## Better fix: make sure the parent passes an array
Wherever you use `UserList`, pass `users`:
```jsx
<UserList users={users} />
```
If `users` comes from an API or state, make sure it…
9.5s601 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):…
Claude Opus 5
# Code Review: `get_data`
Overall, the function works for the happy path, but there are several issues worth addressing — the most serious being the bare `except`, the silent failure mode, and the conflation of two responsibilities (fetching and transforming).
## Critical Issues
### 1. Bare `except` swallows everything
```python
except:
time.sleep(2)
```
This catches `KeyboardInterrupt`, `SystemExit`, `MemoryError`, and — importantly — bugs in your own code. If `item["active"]` raises a `KeyError` because the API changed its schema, you'll retry three times and return `[]`, giving you no indication anything went wrong. Catch `requests.RequestException` instead (the base class for all…
34.7s2823 output tokens
Qwen3.8 27B
The function works at a basic level, but it has several readability, reliability, and best-practice issues.
## Main issues
1. **Imports inside the function**
```python
import requests
import time
```
Imports should normally be at the top of the module unless there is a specific reason to lazy-load them.
2. **Bare `except` is too broad**
```python
except:
time.sleep(2)
```
This catches almost everything, including `KeyboardInterrupt`, `SystemExit`, `KeyError`, `TypeError`, and other programming errors. It makes debugging harder and can retry failures that should not be retried.
3. **It retries on every non-`200` status**
Retrying `401 Unauthorized`, `4…
205.9s13103 output tokens
Frequently asked questions
- Which is cheaper, Claude Opus 5 or Qwen3.8 27B?
- Per 1M output tokens, Claude Opus 5 is ¥4,467.5 and Qwen3.8 27B is ¥571.84 on FastMetal (yen, before tax), so Qwen3.8 27B is cheaper.
- How do the context windows of Claude Opus 5 and Qwen3.8 27B compare?
- Claude Opus 5 takes 1,000,000 tokens; Qwen3.8 27B takes 1,000,000.
- Which ranks higher, Claude Opus 5 or Qwen3.8 27B?
- Claude Opus 5 ranks higher on the public arena (Claude Opus 5 #8, Qwen3.8 27B #87). Ranks move as the leaderboard updates.
- Can I use Claude Opus 5 and Qwen3.8 27B with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-opus-5" or "qwen3.8-27b" 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 Claude Opus 5 and Qwen3.8 27B from the browser chat and the API. No monthly fee.