Claude Opus 5.5 vs MiniMax M3.1 Flash
Pricing, context window and real answers (October 2026)
Claude Opus 5.5 (Anthropic) and MiniMax M3.1 Flash (MiniMax), 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 5.5 |  MiniMax M3.1 Flash | |
|---|---|---|
| Provider | Anthropic | MiniMax |
| Input (per 1M tokens) | $4.22 | $0.1583 |
| Output (per 1M tokens) | $21.10 | $0.633 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | $14.77 | $0.4748 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Release date | 9/22/2026 | 10/19/2026 |
| Input modalities | text, image, file | text, image |
| Throughput (p50) | 166 tokens/s (n=25) | — |
| Arena · overall | #3 · ELO 1,508 | Unranked |
| Arena · Japanese | Unranked | Unranked |
| Arena · coding | #6 · ELO 1,548 | Unranked |
Prices are FastMetal's rates, before tax.
Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-15; category names mapped and ratings rounded by FastMetal.
Which should you pick?
- On price, MiniMax M3.1 Flash: $0.633 per 1M output tokens, 97% less than Claude Opus 5.5.
- For long documents, MiniMax M3.1 Flash: a 1,048,576-token context window against 1,000,000 for Claude Opus 5.5.
- 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 Opus 5.5
# Counting 'r's in "strawberry"
**Step 1: Spell out the word letter by letter.**
| Position | Letter |
|----------|--------|
| 1 | s |
| 2 | t |
| 3 | **r** ← |
| 4 | a |
| 5 | w |
| 6 | b |
| 7 | e |
| 8 | **r** ← |
| 9 | **r** ← |
| 10 | y |
**Step 2: Mark each 'r'.**
- Position 3: the "r" in "st**r**aw"
- Positions 8 and 9: the double "rr" in "be**rr**y"
**Step 3: Add them up.**
1 (in "straw") + 2 (in "berry") = **3**
**Answer: There are 3 'r's in "strawberry."**
A common mistake is to count only 2, because the double "rr" in "berry" can be read as a single sound. Breaking the word into its parts, "straw" + "berry," makes all three easy to see.
5.4s376 output tokens
MiniMax M3.1 Flash
1. Spell **strawberry**:
**s – t – r – a – w – b – e – r – r – y**
2. Count the letter **r**: it appears at positions **3, 8, and 9**.
**Total: 3 “r”s.**
3.0s193 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 5.5
## What's causing it
The error means `users` is `undefined` when `UserList` renders, so `users.map(...)` fails. The component itself is fine. The problem is the value it receives from its parent. Common reasons:
1. **Async data hasn't loaded yet.** This is the most common cause. The parent fetches users from an API, and on the first render the state is still `undefined`:
```jsx
const [users, setUsers] = useState(); // undefined on first render
useEffect(() => {
fetch('/api/users').then(r => r.json()).then(setUsers);
}, []);
return <UserList users={users} />; // crashes before fetch completes
```
2. **The prop isn't being passed**, or has a different name:
```js…
10.9s1040 output tokens
MiniMax M3.1 Flash
The error occurs because `users` is `undefined` when `UserList` renders. Calling `.map()` on `undefined` causes the `TypeError`.
This commonly happens when:
- `<UserList />` is rendered without passing the `users` prop.
- The prop has a different name, such as `user`.
- Data is still loading and the parent initializes its state as `undefined`.
- An API response is accessed before it exists.
### Immediate fix
Provide a default empty array:
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={user.id}>{user.name}</li>
))}
</ul>
);
}
```
Then pass the actual data from the parent:
```jsx
const [users, setUsers] = useState([…
7.3s744 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 5.5
# Code Review: `get_data`
The function works in the happy path, but it has several issues that can hide bugs, waste time, and make failures hard to diagnose.
## Issues
### 🔴 Correctness and Reliability
**1. The bare `except:` is the most serious problem.**
It catches everything, including `KeyboardInterrupt`, `SystemExit`, and bugs in your own code. For example, if an item is missing the `"name"` key, the resulting `KeyError` gets swallowed and the request is retried as if it were a network error. The same happens with invalid JSON. Catch only the exceptions you expect, such as `requests.ConnectionError` and `requests.Timeout`.
**2. Failure is indistinguishable from "no results."**
Ret…
33.5s4023 output tokens
MiniMax M3.1 Flash
The function is understandable, but it has a few important issues:
- `except:` catches programming errors such as `KeyError`, `TypeError`, and even `KeyboardInterrupt`.
- Every non-200 response is retried, including permanent failures such as 400, 401, and 404.
- It sleeps after the final failed attempt.
- Returning `[]` makes a failed request indistinguishable from a successful response containing no active records.
- A fixed delay can cause clients to retry simultaneously; exponential backoff and `Retry-After` are preferable.
- `item["active"] == True` should be `item.get("active") is True` if the API contract says it is a JSON boolean.
- A `Session` can reuse connections, while `requests…
146.5s
Frequently asked questions
- Which is cheaper, Claude Opus 5.5 or MiniMax M3.1 Flash?
- Per 1M output tokens, Claude Opus 5.5 is $21.10 and MiniMax M3.1 Flash is $0.633 on FastMetal (US dollars, before tax), so MiniMax M3.1 Flash is cheaper.
- How do the context windows of Claude Opus 5.5 and MiniMax M3.1 Flash compare?
- Claude Opus 5.5 takes 1,000,000 tokens; MiniMax M3.1 Flash takes 1,048,576.
- Can I use Claude Opus 5.5 and MiniMax M3.1 Flash with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-opus-5-5" or "minimax-m3.1-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 Opus 5.5 and MiniMax M3.1 Flash from the browser chat and the API. No monthly fee.