DeepSeek V4.1 Flash vs Fugu Max
Pricing, context window and real answers (September 2026)
DeepSeek V4.1 Flash (DeepSeek) and Fugu Max (Sakana AI), 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
 DeepSeek V4.1 Flash | Fugu Max | |
|---|---|---|
| Provider | DeepSeek | Sakana AI |
| Input (per 1M tokens) | ¥36.96 | ¥357.4 |
| Output (per 1M tokens) | ¥110.88 | ¥1,072.2 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥92 | ¥894 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Release date | 9/10/2026 | 9/11/2026 |
| Input modalities | text, image | text, image, file |
| Throughput (p50) | — | — |
| Arena · overall | Unranked | Unranked |
| Arena · Japanese | Unranked | Unranked |
| Arena · coding | Unranked | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, DeepSeek V4.1 Flash: ¥110.88 per 1M output tokens, 90% less than Fugu Max.
- For long documents, DeepSeek V4.1 Flash: a 1,048,576-token context window against 1,000,000 for Fugu 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.
DeepSeek V4.1 Flash
The word **“strawberry”** has **3** letter **“r”**s.
Step-by-step:
1. Spell it out: **s t r a w b e r r y**
2. Find each **r**:
- Position 3: **r** in “str”
- Position 8: first **r** in “berry”
- Position 9: second **r** in “berry”
3. Total: **3**
**Answer: 3**
7.5s226 output tokens
Fugu Max
The word **“strawberry”** has **3** letters **“r”**.
Step by step:
1. Write the word: **s t r a w b e r r y**
2. Check each letter:
- s — no
- t — no
- **r** — yes, 1st
- a — no
- w — no
- b — no
- e — no
- **r** — yes, 2nd
- **r** — yes, 3rd
- y — no
So, the total number of **‘r’s** in **“strawberry”** is **3**.
3.7s261 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…
DeepSeek V4.1 Flash
The error means that `users` is `undefined` when `UserList` renders, so JavaScript cannot call `.map()` on it.
Your component expects a `users` prop:
```jsx
function UserList({ users }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
But it is being rendered without `users`, or `users` has not loaded yet.
Common causes:
1. Parent renders it without the prop:
```jsx
<UserList />
```
instead of:
```jsx
<UserList users={users} />
```
2. The prop name is different:
```jsx
<UserList userList={users} />
```
3. The data is fetched asynchronously and is initially `undefined`:
```jsx
const [users, setUsers] = useState();
useEffect(…
16.0s945 output tokens
Fugu Max
The error means `users` is `undefined` when `UserList` renders, so `users.map(...)` throws:
```js
function UserList({ users }) {
// if `users` is not passed, this is undefined
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
Common causes:
1. Parent renders `<UserList />` without the `users` prop.
2. State is initialized as `undefined`:
```js
const [users, setUsers] = useState();
```
3. Async data hasn’t loaded yet, but the component already renders.
4. The API returned something unexpected, e.g. `undefined`, an object, or an error response.
## Fixes
### 1. Default the prop to an empty array
```jsx
function UserList({ use…
10.6s1293 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):…
DeepSeek V4.1 Flash
Here are the main improvements:
- Move imports to module level.
- Avoid bare `except`; catch specific exceptions.
- Use a `requests.Session` for connection reuse.
- Retry only transient network/HTTP failures, not all errors.
- Use exponential backoff and don’t sleep after the final attempt.
- Use a list comprehension for readability/performance.
- Add type hints, logging, constants, and basic JSON validation.
- Avoid `== True`; use `is True` or a truthy check depending on API contract.
Example refactor:
```python
from __future__ import annotations
import logging
import time
from typing import Any
import requests
logger = logging.getLogger(__name__)
TIMEOUT = (3.05, 10) # connect time…
31.5s5142 output tokens
Fugu Max
Here’s a review with concrete improvements.
## Main issues
1. **Bare `except:`**
- Catches everything, including `KeyboardInterrupt`, `SystemExit`, and programming errors.
- Catch `requests.RequestException` instead, plus `ValueError` for JSON parsing if needed.
2. **Retries everything, including non-retryable errors**
- A `404` or `401` will be retried even though retrying will not help.
- Retry only transient failures: network errors, `429`, and `5xx`.
3. **Fixed 2-second sleep**
- No exponential backoff. Repeated retries can hammer the server.
- Use exponential backoff, optionally with jitter.
4. **Silent failure**
- Returning `[]` after all retries makes it hard…
24.7s3795 output tokens
Frequently asked questions
- Which is cheaper, DeepSeek V4.1 Flash or Fugu Max?
- Per 1M output tokens, DeepSeek V4.1 Flash is ¥110.88 and Fugu Max is ¥1,072.2 on FastMetal (yen, before tax), so DeepSeek V4.1 Flash is cheaper.
- How do the context windows of DeepSeek V4.1 Flash and Fugu Max compare?
- DeepSeek V4.1 Flash takes 1,048,576 tokens; Fugu Max takes 1,000,000.
- Can I use DeepSeek V4.1 Flash and Fugu Max with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "deepseek-v4.1-flash" or "fugu-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 DeepSeek V4.1 Flash and Fugu Max from the browser chat and the API. No monthly fee.