DeepSeek V4 Flash vs Ember-1
Pricing, context window and real answers (September 2026)
DeepSeek V4 Flash (DeepSeek) and Ember-1 (Fireworks), 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 Flash | Ember-1 | |
|---|---|---|
| Provider | DeepSeek | Fireworks |
| Input (per 1M tokens) | ¥24.61 | ¥536.1 |
| Output (per 1M tokens) | ¥49.21 | ¥2,680.5 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥49 | ¥1,876 |
| Context window | 1,048,576 tokens | 1,048,576 tokens |
| Release date | 4/24/2026 | 9/24/2026 |
| Input modalities | text | text, image |
| Throughput (p50) | — | — |
| Arena · overall | #92 · ELO 1,436 | Unranked |
| Arena · Japanese | #78 · ELO 1,396 | Unranked |
| Arena · coding | #92 · ELO 1,483 | 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 Flash: ¥49.21 per 1M output tokens, 98% less than Ember-1.
- 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 Flash
The word "strawberry" is spelled as s-t-r-a-w-b-e-r-r-y. I go through each letter: s (no), t (no), r (yes, first), a (no), w (no), b (no), e (no), r (yes, second), r (yes, third), y (no). Thus, there are three 'r's.
3.9s251 output tokens
Ember-1
# Counting the 'r's in "strawberry"
**Step 1: Write out the word letter by letter**
s - t - r - a - w - b - e - r - r - y
**Step 2: Examine each letter one at a time**
| Position | Letter | Is it 'r'? |
|----------|--------|------------|
| 1 | s | No |
| 2 | t | No |
| 3 | r | ✅ Yes (1) |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | r | ✅ Yes (2) |
| 9 | r | ✅ Yes (3) |
| 10 | y | No |
**Step 3: Verify by splitting the word into parts**
- "straw" → contains **1** r
- "berry" → contains **2** r's
- Total: 1 + 2 = **3**
## Answer
The word "strawberry" contains **3** r's.
8.2s482 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 Flash
The error occurs because `users` is `undefined` when the component tries to call `.map()` on it.
## Why this happens
Your component expects `users` to be an array, but it's receiving `undefined` as a prop. This typically happens when:
1. The parent component doesn't pass the `users` prop
2. The data fetching hasn't completed yet (async data loading)
3. The API response is missing the expected data structure
## How to fix it
### Option 1: Default prop value (Recommended for initial state)
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
### Option 2: Guard clause (More explicit)
```jsx
func…
6.3s422 output tokens
Ember-1
## The Cause
The error means `users` is `undefined` when the component renders, so calling `.map()` on it fails. The component itself is fine — the problem is that the `users` prop isn't being provided (or isn't ready yet).
The most common reasons this happens:
1. **Async data hasn't loaded yet** — the parent fetches users from an API, and the component renders before the fetch completes:
```jsx
const [users, setUsers] = useState(); // undefined initially!
```
2. **The prop isn't passed or is misspelled** in the parent:
```jsx
<UserList user={users} /> // typo: should be "users"
```
3. **Wrong data shape** — e.g., passing the whole response object instead of `response…
18.2s960 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 Flash
Here's a comprehensive review with suggested improvements:
## Issues Identified:
1. **Import at wrong location** - Imports inside functions are inefficient and non-standard
2. **Bare `except:` clause** - Catches all exceptions including `KeyboardInterrupt`, `SystemExit`
3. **Missing error handling granularity** - Should distinguish between retryable and non-retryable errors
4. **Duplicate sleep logic** - Same sleep in `else` and `except` blocks
5. **Unnecessary variable** - `data` is only used once
6. **Inefficient list building** - Manual loop instead of list comprehension
7. **Hardcoded error message** - No logging or error context
8. **Missing type hints** - No type annotations
9. **Fun…
12.6s987 output tokens
Ember-1
# Code Review
## Bugs and correctness issues
- **Bare `except:`** catches *everything* — including `KeyboardInterrupt` and, critically, `KeyError` from `item["active"]`. A malformed item in the response would be misinterpreted as a network failure, wasting all your retries on a data problem that retrying can't fix.
- **Retrying all non-200 statuses** — a 404 or 401 will never succeed on retry. Only transient errors (connection failures, timeouts, 429, 5xx) are worth retrying.
- **Wasted sleep on the final attempt** — the loop sleeps 2 seconds even after the last failure, before returning `[]`.
- **Ambiguous return value** — `[]` means both "request failed" and "no active items." Callers ca…
95.0s5356 output tokens
Frequently asked questions
- Which is cheaper, DeepSeek V4 Flash or Ember-1?
- Per 1M output tokens, DeepSeek V4 Flash is ¥49.21 and Ember-1 is ¥2,680.5 on FastMetal (yen, before tax), so DeepSeek V4 Flash is cheaper.
- How do the context windows of DeepSeek V4 Flash and Ember-1 compare?
- DeepSeek V4 Flash takes 1,048,576 tokens; Ember-1 takes 1,048,576.
- Can I use DeepSeek V4 Flash and Ember-1 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "deepseek-v4-flash" or "ember-1" 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 Flash and Ember-1 from the browser chat and the API. No monthly fee.