Claude Sonnet 4.6 vs Inkling
Pricing, context window and real answers (August 2026)
Claude Sonnet 4.6 (Anthropic) and Inkling (Thinkingmachines), 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 Sonnet 4.6 | Inkling | |
|---|---|---|
| Provider | Anthropic | Thinkingmachines |
| Input (per 1M tokens) | ¥554.4 | ¥178.7 |
| Output (per 1M tokens) | ¥2,772 | ¥723.74 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,940 | ¥541 |
| Context window | 1,000,000 tokens | 524,288 tokens |
| Release date | 2/17/2026 | 7/17/2026 |
| Input modalities | text, image | text, image, audio |
| Arena · overall | #32 · ELO 1,472 | #81 · ELO 1,439 |
| Arena · Japanese | #41 · ELO 1,438 | #52 · ELO 1,425 |
| Arena · coding | #14 · ELO 1,528 | #80 · ELO 1,489 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Inkling: ¥723.74 per 1M output tokens, 74% less than Claude Sonnet 4.6.
- On the Overall arena board, Claude Sonnet 4.6 ranks higher (#32; Inkling is #81).
- On the Japanese arena board, Claude Sonnet 4.6 ranks higher (#41; Inkling is #52).
- On the Coding arena board, Claude Sonnet 4.6 ranks higher (#14; Inkling is #80).
- For long documents, Claude Sonnet 4.6: a 1,000,000-token context window against 524,288 for Inkling.
- 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 Sonnet 4.6
## Counting the letter 'r' in 'strawberry'
Let me go through the word letter by letter:
| 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 |
## Result
There are **3 r's** in 'strawberry'.
2.2s181 output tokens
Inkling
Let's break down the word **"strawberry"** letter by letter:
1. **s**
2. **t**
3. **r** ← (1st 'r')
4. **a**
5. **w**
6. **b**
7. **e**
8. **r** ← (2nd 'r')
9. **r** ← (3rd 'r')
10. **y**
So the spelling is: s-t-**r**-a-w-b-e-**r**-**r**-y
Counting them up:
- One 'r' in "str" (the 3rd letter)
- Two 'r's in "berry" (the 8th and 9th letters)
**Total: 3 'r's** in "strawberry".**
2.4s417 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 Sonnet 4.6
## Problem Analysis
The error occurs because `users` is `undefined` when the component renders. You're calling `.map()` on `undefined`, which throws a `TypeError`.
**Common causes:**
- The prop isn't passed by the parent component
- Data is still loading asynchronously when the component first renders
- The parent passes `undefined` or a misspelled prop name
---
## Solutions
### Option 1: Default Parameter Value (Simplest Fix)
```javascript
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
This assigns an empty array if `users` is `undefined`, so `.map()` always has an array to work with.
---
###…
9.4s798 output tokens
Inkling
The error occurs because `users` is `undefined` when `UserList` renders, so `users.map` fails.
This usually happens when:
- The parent doesn't pass the prop (`<UserList />` instead of `<UserList users={...} />`)
- Data is still loading (e.g., API hasn't returned yet)
## Quick Fix
Provide a default empty array so `.map` always has an array to work with:
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
Alternatively, guard against undefined explicitly:
```jsx
function UserList({ users }) {
if (!users) return null; // or a loading state
return (
<ul>
{users.map(user => <li key={…
4.9s585 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 Sonnet 4.6
## Code Review and Improvements
### Issues Identified
1. **Imports inside function** – should be at module level
2. **Bare `except`** – catches everything including `KeyboardInterrupt`, `SystemExit`
3. **`== True` comparison** – not Pythonic
4. **No logging/error visibility** – silent failures make debugging hard
5. **Magic numbers** – hardcoded `2`, `10` with no explanation
6. **No distinction between retriable/non-retriable errors** – e.g., 404 should not be retried
7. **Inefficient list building** – list comprehension is cleaner
8. **No exponential backoff** – fixed sleep is naive for real-world retry logic
9. **Missing type hints and docstring**
---
### Improved Version
```python
im…
14.4s1099 output tokens
Inkling
Here is a review with an improved version followed by explanations.
### Issues in the original
- **Imports inside the function**: Re-importing on every call is inefficient.
- **Bare `except:`**: Catches `SystemExit`, `KeyboardInterrupt`, etc.
- **Silent failures**: No logging; errors disappear.
- **Magic numbers**: `10`, `2`, `200` are hard-coded.
- **Data validation missing**: Assumes `data` is a list and every item has `"active"`, `"name"`, and `"id"` (will crash with `KeyError`).
- **Performance**: Uses `.append()` in a loop instead of a list comprehension.
- **Ambiguous return**: `[]` means both "success with no results" and "total failure".
### Improved version
```python
import loggi…
54.1s5649 output tokens
Frequently asked questions
- Which is cheaper, Claude Sonnet 4.6 or Inkling?
- Per 1M output tokens, Claude Sonnet 4.6 is ¥2,772 and Inkling is ¥723.74 on FastMetal (yen, before tax), so Inkling is cheaper.
- How do the context windows of Claude Sonnet 4.6 and Inkling compare?
- Claude Sonnet 4.6 takes 1,000,000 tokens; Inkling takes 524,288.
- Which ranks higher, Claude Sonnet 4.6 or Inkling?
- Claude Sonnet 4.6 ranks higher on the public arena (Claude Sonnet 4.6 #41, Inkling #52). Ranks move as the leaderboard updates.
- Can I use Claude Sonnet 4.6 and Inkling with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-sonnet-4-6" or "inkling" 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 Sonnet 4.6 and Inkling from the browser chat and the API. No monthly fee.