Claude Haiku 4.5 vs DeepSeek V4 Flash
Pricing, context window and real answers (August 2026)
Claude Haiku 4.5 (Anthropic) and DeepSeek V4 Flash (DeepSeek), 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
 Claude Haiku 4.5 |  DeepSeek V4 Flash | |
|---|---|---|
| Provider | Anthropic | DeepSeek |
| Input (per 1M tokens) | ¥184.8 | ¥16.08 |
| Output (per 1M tokens) | ¥924 | ¥32.17 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥647 | ¥32 |
| Context window | 200,000 tokens | 1,048,576 tokens |
| Release date | 10/15/2025 | 4/24/2026 |
| Input modalities | image, text | text |
| Arena · overall | #120 · ELO 1,412 | #79 · ELO 1,436 |
| Arena · Japanese | #99 · ELO 1,355 | #67 · ELO 1,390 |
| Arena · coding | #86 · ELO 1,479 | #80 · ELO 1,484 |
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: ¥32.17 per 1M output tokens, 97% less than Claude Haiku 4.5.
- On the Overall arena board, DeepSeek V4 Flash ranks higher (#79; Claude Haiku 4.5 is #120).
- On the Japanese arena board, DeepSeek V4 Flash ranks higher (#67; Claude Haiku 4.5 is #99).
- On the Coding arena board, DeepSeek V4 Flash ranks higher (#80; Claude Haiku 4.5 is #86).
- For long documents, DeepSeek V4 Flash: a 1,048,576-token context window against 200,000 for Claude Haiku 4.5.
- 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.
Claude Haiku 4.5
# Counting the 'r's in "strawberry"
Let me go through each letter in the word "strawberry":
1. **s** - not an 'r'
2. **t** - not an 'r'
3. **r** - this is an 'r' ✓ (1st)
4. **a** - not an 'r'
5. **w** - not an 'r'
6. **b** - not an 'r'
7. **e** - not an 'r'
8. **r** - this is an 'r' ✓ (2nd)
9. **r** - this is an 'r' ✓ (3rd)
10. **y** - not an 'r'
**Answer: There are 3 'r's in "strawberry"**
The 'r's appear in positions 3, 8, and 9 of the word.
4.1s228 output tokens
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
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…
Claude Haiku 4.5
# TypeError: Cannot read properties of undefined (reading 'map')
This error occurs because `users` is `undefined` when the component renders. You're trying to call `.map()` on `undefined`, which doesn't have that method.
## Common Causes
1. **Parent component didn't pass the `users` prop**
2. **Async data hasn't loaded yet**
3. **Props passed incorrectly**
## Solutions
### 1. **Provide a Default Value** (Recommended)
```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 <p>No users a…
3.9s671 output tokens
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
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):…
Claude Haiku 4.5
# Code Review and Improvements
## Issues Found
1. **Bare `except`** - Catches all exceptions, hiding bugs
2. **Imports inside function** - Should be at module level
3. **Redundant comparison** - `== True` is unnecessary
4. **No logging** - Hard to debug failures
5. **Magic numbers** - Hardcoded timeout and sleep values
6. **Inefficient retries** - Doesn't retry on 200 with parsing errors
7. **Poor variable names** - `r`, `i` are unclear
8. **No type hints** - Reduces code clarity
## Improved Version
```python
import logging
import requests
import time
from typing import Optional
from requests.exceptions import RequestException
logger = logging.getLogger(__name__)
def get_data(
url:…
5.7s988 output tokens
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
Frequently asked questions
- Which is cheaper, Claude Haiku 4.5 or DeepSeek V4 Flash?
- Per 1M output tokens, Claude Haiku 4.5 is ¥924 and DeepSeek V4 Flash is ¥32.17 on FastMetal (yen, before tax), so DeepSeek V4 Flash is cheaper.
- How do the context windows of Claude Haiku 4.5 and DeepSeek V4 Flash compare?
- Claude Haiku 4.5 takes 200,000 tokens; DeepSeek V4 Flash takes 1,048,576.
- Which ranks higher, Claude Haiku 4.5 or DeepSeek V4 Flash?
- DeepSeek V4 Flash ranks higher on the public arena (Claude Haiku 4.5 #99, DeepSeek V4 Flash #67). Ranks move as the leaderboard updates.
- Can I use Claude Haiku 4.5 and DeepSeek V4 Flash with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-haiku-4-5" or "deepseek-v4-flash" 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 Claude Haiku 4.5 and DeepSeek V4 Flash from the browser chat and the API. No monthly fee.