DeepSeek V4 Pro vs Fugu Ultra v2
Pricing, context window and real answers (September 2026)
DeepSeek V4 Pro (DeepSeek) and Fugu Ultra v2 (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 Pro | Fugu Ultra v2 | |
|---|---|---|
| Provider | DeepSeek | Sakana AI |
| Input (per 1M tokens) | ¥341.32 | ¥893.5 |
| Output (per 1M tokens) | ¥684.42 | ¥5,361 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥684 | ¥3,574 |
| Context window | 1,048,576 tokens | 1,000,000 tokens |
| Release date | 4/24/2026 | 9/11/2026 |
| Input modalities | text | text, image, file |
| Throughput (p50) | — | — |
| Arena · overall | #57 · ELO 1,457 | Unranked |
| Arena · Japanese | #22 · ELO 1,462 | Unranked |
| Arena · coding | #65 · ELO 1,501 | 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 Pro: ¥684.42 per 1M output tokens, 87% less than Fugu Ultra v2.
- For long documents, DeepSeek V4 Pro: a 1,048,576-token context window against 1,000,000 for Fugu Ultra v2.
- 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 Pro
The word is "strawberry". Let's count the occurrences of the letter 'r' step by step:
1. Write the word: s t r a w b e r r y
2. Examine each character:
- s: not an 'r'
- t: not an 'r'
- r: is an 'r' → count 1
- a: not an 'r'
- w: not an 'r'
- b: not an 'r'
- e: not an 'r'
- r: is an 'r' → count 2
- r: is an 'r' → count 3
- y: not an 'r'
3. Total number of 'r's = 3.
Therefore, there are **3** 'r's in "strawberry".
7.3s1136 output tokens
Fugu Ultra v2
**Answer: 3**
**Step-by-step reasoning:**
1. **Write out the word letter by letter**, assigning each a position:
| Position | Letter | Is it 'r'? |
|---|---|---|
| 1 | s | no |
| 2 | t | no |
| 3 | **r** | ✅ yes |
| 4 | a | no |
| 5 | w | no |
| 6 | b | no |
| 7 | e | no |
| 8 | **r** | ✅ yes |
| 9 | **r** | ✅ yes |
| 10 | y | no |
2. **Tally the matches:** positions 3, 8, and 9 are 'r'.
3. **Sanity check by chunks:** "straw" contains one 'r' (str**a**w → the r in "str"), and "berry" contains two 'r's (be**rr**y). 1 + 2 = 3.
4. **Verify length:** the letters counted total 10, which matches the length of "strawberry" — so no letter was skipped or double-counted.
**Conclusion:** There a…
10.2s435 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 Pro
The error is occurring because `users` is `undefined` when the component renders, and you're trying to call `.map()` on it. This typically happens when the data hasn't been loaded yet or wasn't passed correctly to the component.
## Here are several ways to fix this:
### 1. **Add a default value with empty array (Simplest fix)**
```javascript
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
### 2. **Add a conditional check**
```javascript
function UserList({ users }) {
if (!users) {
return <div>No users found</div>;
}
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}<…
6.9s442 output tokens
Fugu Ultra v2
## What the error means
`TypeError: Cannot read properties of undefined (reading 'map')` means that when `UserList` rendered, `users` was `undefined`, and JavaScript can't read the `.map` property off `undefined`.
The important detail: **the bug isn't really in `UserList`** — that's just where it surfaces. Destructuring `function UserList({ users })` does *not* throw when the prop is missing; it silently gives you `undefined`. The crash is deferred to the first property access, which is `.map` on line 12.
So the real question is: why is `props.users` not an array?
## Why `users` is undefined
**1. Async data hasn't arrived yet — by far the most common cause.**
```jsx
const [users, setUs…
70.8s5286 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 Pro
Here’s a review of your `get_data` function, highlighting issues and suggesting improvements.
## Overall Observations
- The function works but has several readability, robustness, and maintainability issues.
- Imports are inside the function, bare `except` hides errors, and the filtering logic is not Pythonic.
- No type hints or docstring, making it harder to use and understand.
## Specific Improvements
### 1. Move Imports to the Top of the Module
**Why:** Imports inside a function are executed every time the function is called, which is slightly slower and violates PEP 8 style guidelines.
**Before:**
```python
def get_data(url, retries=3):
import requests
import time
# ...
`…
40.5s2277 output tokens
Fugu Ultra v2
# Final Code Review: `get_data`
The function is compact and its intent is clear, but as written it will **fail silently in production**. Two defects dominate everything else:
1. The bare `except:` swallows every error — including `KeyboardInterrupt` and genuine logic bugs.
2. A total failure and a legitimately empty dataset both return `[]`, so callers cannot tell "the service is down" from "there are no active records."
Together these mean an outage looks exactly like a successful empty response. Everything else below is meaningful improvement; those two are the difference between code that fails loudly and code that fails invisibly.
---
## 1. Correctness and error handling
### 1.1 `e…
281.1s23317 output tokens
Frequently asked questions
- Which is cheaper, DeepSeek V4 Pro or Fugu Ultra v2?
- Per 1M output tokens, DeepSeek V4 Pro is ¥684.42 and Fugu Ultra v2 is ¥5,361 on FastMetal (yen, before tax), so DeepSeek V4 Pro is cheaper.
- How do the context windows of DeepSeek V4 Pro and Fugu Ultra v2 compare?
- DeepSeek V4 Pro takes 1,048,576 tokens; Fugu Ultra v2 takes 1,000,000.
- Can I use DeepSeek V4 Pro and Fugu Ultra v2 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "deepseek-v4-pro" or "fugu-ultra-v2" 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 Pro and Fugu Ultra v2 from the browser chat and the API. No monthly fee.