Claude Opus 4.8 vs Muse Spark 1.2
Pricing, context window and real answers (August 2026)
Claude Opus 4.8 (Anthropic) and Muse Spark 1.2 (Meta), 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 Opus 4.8 |  Muse Spark 1.2 | |
|---|---|---|
| Provider | Anthropic | Meta |
| Input (per 1M tokens) | ¥893.5 | ¥219.9 |
| Output (per 1M tokens) | ¥4,467.5 | ¥747.65 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥3,127 | ¥594 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Release date | 5/27/2026 | 8/5/2026 |
| Input modalities | text, image, file | text, image, video, file, audio |
| Arena · overall | #31 · ELO 1,473 | #4 · ELO 1,498 |
| Arena · Japanese | #30 · ELO 1,450 | Unranked |
| Arena · coding | #16 · ELO 1,527 | #7 · ELO 1,533 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Muse Spark 1.2: ¥747.65 per 1M output tokens, 83% less than Claude Opus 4.8.
- On the Overall arena board, Muse Spark 1.2 ranks higher (#4; Claude Opus 4.8 is #31).
- On the Coding arena board, Muse Spark 1.2 ranks higher (#7; Claude Opus 4.8 is #16).
- For long documents, Muse Spark 1.2: a 1,048,576-token context window against 1,000,000 for Claude Opus 4.8.
- 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 Opus 4.8
# Counting 'r's in "strawberry"
## Step-by-step process:
Let me go through 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 |
## Answer:
There are **3** 'r's in "strawberry".
The three 'r's appear at positions 3, 8, and 9 — one after the "st" and two together in the "rry" ending.
4.5s262 output tokens
Muse Spark 1.2
There are **3** 'r's in "strawberry".
Here is my reasoning step by step:
1. Write out the word and its spelling: **s-t-r-a-w-b-e-r-r-y**
2. Go through each letter one by one and check if it is an 'r':
* 1. s - not an 'r' -> count = 0
* 2. t - not an 'r' -> count = 0
* 3. **r** - yes, it's an 'r' -> count = 1
* 4. a - not an 'r' -> count = 1
* 5. w - not an 'r' -> count = 1
* 6. b - not an 'r' -> count = 1
* 7. e - not an 'r' -> count = 1
* 8. **r** - yes, it's an 'r' -> count = 2
* 9. **r** - yes, it's an 'r' -> count = 3
* 10. y - not an 'r' -> count = 3
3. Final total = **3**.
13.3s1123 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 Opus 4.8
# What's Causing the Error
The error tells you exactly what's happening:
```
TypeError: Cannot read properties of undefined (reading 'map')
at UserList (/app/components/UserList.js:12:25)
```
At the moment `UserList` renders, the `users` prop is `undefined`, and you can't call `.map()` on `undefined`. This is extremely common when data is fetched asynchronously—the component renders **before** the data arrives.
Common reasons `users` is undefined:
- The parent hasn't passed the `users` prop at all
- Data is still loading from an API (initial state is `undefined`)
- The API response shape differs from what you expect (e.g. `data.users` vs `data`)
---
# How to Fix It
## Option 1: De…
11.3s761 output tokens
Muse Spark 1.2
This error means `users` is `undefined` when the component tries to render.
You are calling `.map()` on `users` at line 12, but `.map()` only exists on arrays. If `users` is `undefined` or `null`, JavaScript throws: `Cannot read properties of undefined (reading 'map')`.
This usually happens for 2 reasons:
1. You didn't pass the `users` prop to the component: `<UserList />`
2. Your data is async and `users` is `undefined` on the first render. For example: `const [users, setUsers] = useState()` without an initial value, and the data hasn't been fetched yet.
### Fix it
You need to guarantee `users` is always an array before you call `.map()`.
#### 1. Best Fix: Give it a default value
U…
7.6s1142 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 Opus 4.8
# Code Review
Here's a breakdown of issues and suggested improvements for your function.
## Key Issues
1. **Imports inside the function** — should be at module level (runs on every call, harder to see dependencies).
2. **Bare `except:`** — catches everything, including `KeyboardInterrupt` and `SystemExit`. Silently swallowing errors makes debugging hard.
3. **Magic numbers** — `10`, `2`, `200` scattered around; extract as parameters/constants.
4. **`== True` comparison** — non-Pythonic; use the value directly (or `is True` if strict).
5. **Blocking `time.sleep(2)`** — fixed delay; exponential backoff is a better practice.
6. **`r.status_code == 200`** — misses other success codes; use `ra…
16.9s1403 output tokens
Muse Spark 1.2
Here is a review of your function with a refactored, production-ready version:
### Issues in the Current Version
#### 1. Readability
1. **Generic name:** `get_data` tells nothing about what it does. `get_active_items` is better.
2. **Imports inside function:** `import requests, time` should be at the top of the file. It's slower and violates PEP 8.
3. **Magic numbers:** `200`, `10`, `2` have no context.
4. **Verbose loop:** Manual `for` loop + `append` can be replaced with a list comprehension.
5. **No documentation/typing:** No docstring, no type hints, so callers don't know what it expects or returns.
6. **`== True` is redundant:** `if item["active"] == True:` should be `if item["a…
11.8s2278 output tokens
Frequently asked questions
- Which is cheaper, Claude Opus 4.8 or Muse Spark 1.2?
- Per 1M output tokens, Claude Opus 4.8 is ¥4,467.5 and Muse Spark 1.2 is ¥747.65 on FastMetal (yen, before tax), so Muse Spark 1.2 is cheaper.
- How do the context windows of Claude Opus 4.8 and Muse Spark 1.2 compare?
- Claude Opus 4.8 takes 1,000,000 tokens; Muse Spark 1.2 takes 1,048,576.
- Which ranks higher, Claude Opus 4.8 or Muse Spark 1.2?
- Muse Spark 1.2 ranks higher on the public arena (Claude Opus 4.8 #30, Muse Spark 1.2 #4). Ranks move as the leaderboard updates.
- Can I use Claude Opus 4.8 and Muse Spark 1.2 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-opus-4-8" or "muse-spark-1.2" 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 Opus 4.8 and Muse Spark 1.2 from the browser chat and the API. No monthly fee.