Grok 4.7 vs Kimi K3
Pricing, context window and real answers (September 2026)
Grok 4.7 (xAI) and Kimi K3 (Moonshot), 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
 Grok 4.7 |  Kimi K3 | |
|---|---|---|
| Provider | xAI | Moonshot |
| Input (per 1M tokens) | ¥276.2 | ¥504 |
| Output (per 1M tokens) | ¥828.6 | ¥2,520 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥691 | ¥1,764 |
| Context window | 500,000 tokens | 1,048,576 tokens |
| Release date | 9/21/2026 | 7/16/2026 |
| Input modalities | text, image, file | text, image |
| Throughput (p50) | — | — |
| Arena · overall | Unranked | #17 · ELO 1,485 |
| Arena · Japanese | Unranked | #2 · ELO 1,511 |
| Arena · coding | Unranked | #7 · ELO 1,538 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Grok 4.7: ¥828.6 per 1M output tokens, 67% less than Kimi K3.
- For long documents, Kimi K3: a 1,048,576-token context window against 500,000 for Grok 4.7.
- 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.
Grok 4.7
The word "strawberry" consists of the letters S-T-R-A-W-B-E-R-R-Y.
- The 3rd letter is R.
- The 8th letter is R.
- The 9th letter is R.
This gives a total of 3 R's.
4.7s299 output tokens
Kimi K3
# Counting the 'r's in "strawberry"
**Step 1: Write out each letter with its position**
| 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 'r'**
- Position 3: the 'r' in "st**r**"
- Position 8: the first 'r' in "be**r**ry"
- Position 9: the second 'r' in "ber**r**y"
**Step 3: Verify by splitting the word**
"Strawberry" = "straw" + "berry"
- "straw" contains **1** r
- "berry" contains **2** r's
**Answer: There are 3 r's in "strawberry."** 🍓
12.2s594 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…
Grok 4.7
The error happens because `users` is `undefined` when `UserList` renders, so calling `.map` on it fails.
That usually means the parent rendered `<UserList />` (or `<UserList users={undefined} />`) before data was loaded, or the prop name doesn’t match.
**Fix it in the component** so it tolerates a missing list:
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
Or guard the call:
```jsx
function UserList({ users }) {
return (
<ul>
{(users ?? []).map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
**Also check the parent** so you pass an array once data exists:
`…
12.8s393 output tokens
Kimi K3
## What's causing it
The error means `users` is `undefined` when the component renders — `.map()` only exists on arrays, so calling it on `undefined` throws. Your component code is fine; the problem is **upstream**: whatever renders `<UserList />` isn't passing a valid array.
The most common culprit is **async data fetching with uninitialized state** in the parent:
```jsx
function App() {
const [users, setUsers] = useState(); // ← undefined!
useEffect(() => {
fetch('/api/users')
.then(res => res.json())
.then(setUsers);
}, []);
return <UserList users={users} />; // undefined on first render
}
```
The component renders *before* the fetch resolves, so `users` is `…
47.5s1756 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):…
Grok 4.7
## Review
The function works for the happy path, but it hides failures, retries the wrong errors, and is harder to read and debug than it needs to be.
### Issues
1. **Imports inside the function** — move them to module level unless you have a strong reason (circular imports, optional dependency).
2. **Bare `except`** — swallows `KeyboardInterrupt`, `SystemExit`, and programming bugs. Catch specific exceptions.
3. **Retries non-retryable failures** — 4xx (except maybe 429) will not succeed on retry. Network errors and 5xx are the usual candidates.
4. **Sleeps after the last attempt** — wastes up to 2 seconds before returning `[]`.
5. **Unused loop variable** and vague names (`r`, `i`).
6.…
22.3s1525 output tokens
Kimi K3
This works, but there are several issues worth addressing. Here's a breakdown, followed by an improved version.
## Issues
### Correctness & best practices
1. **Bare `except:`** — catches *everything*, including `KeyboardInterrupt` and programming bugs like `KeyError` on a malformed item (which then get pointlessly retried). Catch `requests.RequestException` specifically.
2. **Silent failures** — errors are swallowed with no logging, and returning `[]` makes "API is down" indistinguishable from "no active items." At minimum, log; ideally, raise after the final attempt.
3. **Retrying non-retryable errors** — a 400/401/404 will never succeed on retry, but the code sleeps and retries anyway. O…
57.6s8060 output tokens
Frequently asked questions
- Which is cheaper, Grok 4.7 or Kimi K3?
- Per 1M output tokens, Grok 4.7 is ¥828.6 and Kimi K3 is ¥2,520 on FastMetal (yen, before tax), so Grok 4.7 is cheaper.
- How do the context windows of Grok 4.7 and Kimi K3 compare?
- Grok 4.7 takes 500,000 tokens; Kimi K3 takes 1,048,576.
- Can I use Grok 4.7 and Kimi K3 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "grok-4.7" or "kimi-k3" 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 Grok 4.7 and Kimi K3 from the browser chat and the API. No monthly fee.