Kimi K3.1 Pro vs Qwen3.8 Max
Pricing, context window and real answers (October 2026)
Kimi K3.1 Pro (Moonshot) and Qwen3.8 Max (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
 Kimi K3.1 Pro |  Qwen3.8 Max | |
|---|---|---|
| Provider | Moonshot | Qwen |
| Input (per 1M tokens) | $2.11 | $2.11 |
| Output (per 1M tokens) | $10.55 | $6.33 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | $7.39 | $5.28 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Release date | 10/23/2026 | 8/3/2026 |
| Input modalities | text, image, video | text, image |
| Throughput (p50) | — | 70 tokens/s (n=27) |
| Arena · overall | Unranked | #23 · ELO 1,483 |
| Arena · Japanese | Unranked | #21 · ELO 1,478 |
| Arena · coding | Unranked | #29 · ELO 1,524 |
Prices are FastMetal's rates, before tax.
Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-22; category names mapped and ratings rounded by FastMetal.
Which should you pick?
- On price, Qwen3.8 Max: $6.33 per 1M output tokens, 40% less than Kimi K3.1 Pro.
- For long documents, Kimi K3.1 Pro: a 1,048,576-token context window against 1,000,000 for Qwen3.8 Max.
- 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.
Kimi K3.1 Pro
There are **3** ‘r’s in **“strawberry.”**
1. Write out each letter: **s – t – r – a – w – b – e – r – r – y**
2. Locate the ‘r’s: positions **3, 8, and 9**.
3. Count them: **1 + 1 + 1 = 3**.
11.3s
Qwen3.8 Max
The word **strawberry** is spelled:
**s t r a w b e r r y**
Now count the letter **r**:
1. s
2. t
3. **r** ← first r
4. a
5. w
6. b
7. e
8. **r** ← second r
9. **r** ← third r
10. y
There are **3** letters **r** in **strawberry**.
3.5s156 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…
Kimi K3.1 Pro
## What's causing the error
The error means `users` is `undefined` when the component renders, and you can't call `.map()` on `undefined`. The component itself is fine — the problem is that whatever renders `<UserList />` either isn't passing the prop, or is passing a value that isn't an array yet.
The most common cause is **async data fetching**: the parent renders `UserList` before the data has loaded.
```jsx
function App() {
const [users, setUsers] = useState(); // ❌ undefined on first render
useEffect(() => {
fetch('/api/users')
.then(res => res.json())
.then(setUsers);
}, []);
return <UserList users={users} />; // users is undefined here initially
}
```
On…
36.3s
Qwen3.8 Max
The error means `users` is `undefined` when `UserList` tries to render:
```js
{users.map(user => ...)}
```
JavaScript cannot call `.map()` on `undefined`, so React throws:
```text
Cannot read properties of undefined (reading 'map')
```
## Most likely cause
The parent component is rendering `UserList` without passing a valid `users` array, or it is passing `users` before the data has loaded.
For example:
```jsx
<UserList />
```
or:
```jsx
<UserList users={undefined} />
```
or:
```jsx
const [users, setUsers] = useState(); // undefined initially
```
Then later:
```jsx
<UserList users={users} />
```
On the first render, `users` is still `undefined`.
---
## Fix 1: Give `users` a d…
17.7s1020 output tokens
Professional Email
Write a professional email to a client explaining that the project delivery will be delayed by two weeks due to unexpected technical challenges discovered during integration testing. The tone should be apologetic but con…
Kimi K3.1 Pro
**Subject: Revised Delivery Timeline for [Project Name]**
Dear [Client Name],
I’m writing to inform you that we need to revise the delivery date for [Project Name] from **[Original Delivery Date]** to **[Revised Delivery Date]**, a delay of two weeks. During integration testing, we identified unexpected technical challenges that require additional remediation and retesting before we can confidently release the solution.
We sincerely apologize for the inconvenience this may cause and understand the importance of the original timeline. After assessing the issues, we determined that taking this additional time is necessary to protect the quality, stability, and long-term success of the deliv…
57.7s
Qwen3.8 Max
Subject: Revised Project Delivery Timeline – Updated Schedule and Next Steps
Dear [Client Name],
I hope this message finds you well.
I am writing to provide an update on the current status of the project and to inform you that, during our recent integration testing phase, we encountered several unexpected technical challenges that will impact the original delivery timeline. After careful review with the technical team, we now anticipate the revised delivery date will be [insert date – two weeks from original delivery date].
Please accept my sincere apologies for this delay. We understand the importance of this project and the expectations tied to the original schedule. While this situati…
11.9s547 output tokens
Frequently asked questions
- Which is cheaper, Kimi K3.1 Pro or Qwen3.8 Max?
- Per 1M output tokens, Kimi K3.1 Pro is $10.55 and Qwen3.8 Max is $6.33 on FastMetal (US dollars, before tax), so Qwen3.8 Max is cheaper.
- How do the context windows of Kimi K3.1 Pro and Qwen3.8 Max compare?
- Kimi K3.1 Pro takes 1,048,576 tokens; Qwen3.8 Max takes 1,000,000.
- Can I use Kimi K3.1 Pro and Qwen3.8 Max with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "kimi-k3.1-pro" or "qwen3.8-max" 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 Kimi K3.1 Pro and Qwen3.8 Max from the browser chat and the API. No monthly fee.