Claude Opus 5.5 vs MiniMax M3
Pricing, context window and real answers (September 2026)
Claude Opus 5.5 (Anthropic) and MiniMax M3 (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 | |
|---|---|---|
| Provider | Anthropic | MiniMax |
| Input (per 1M tokens) | ¥692.4 | ¥53.61 |
| Output (per 1M tokens) | ¥3,462 | ¥214.44 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥2,423 | ¥161 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Release date | 9/22/2026 | 5/31/2026 |
| Input modalities | text, image, file | text, image, video |
| Throughput (p50) | — | — |
| Arena · overall | Unranked | #84 · ELO 1,441 |
| Arena · Japanese | Unranked | #77 · ELO 1,398 |
| Arena · coding | Unranked | #73 · ELO 1,496 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, MiniMax M3: ¥214.44 per 1M output tokens, 94% less than Claude Opus 5.5.
- For long documents, MiniMax M3: 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
# Counting 'r's in "strawberry"
Let me go through the word letter by letter:
**s** - t - **r** - a - w - b - e - **r** - **r** - y
| Position | Letter | Is it 'r'? |
|----------|--------|------------|
| 1 | s | No |
| 2 | t | No |
| 3 | **r** | ✓ (1st) |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | **r** | ✓ (2nd) |
| 9 | **r** | ✓ (3rd) |
| 10 | y | No |
## Answer: **3**
The word "strawberry" contains **three 'r's** — one at position 3, and two consecutive 'r's at positions 8 and 9.
25.6s455 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
# Error Analysis
The error `Cannot read properties of undefined (reading 'map')` tells you that **`users` is `undefined`** when your component runs. JavaScript can't call `.map()` on `undefined`, so it throws this error.
The component itself is fine syntactically — the problem is that the `users` prop isn't being passed, or hasn't loaded yet.
## Common Causes
**1. The prop isn't passed at all:**
```jsx
<UserList /> // No users prop → users is undefined
```
**2. Data is still loading (async fetch):**
```jsx
const [users, setUsers] = useState(); // undefined initially
```
**3. API returns undefined:**
```jsx
const { data } = await fetch('/api/users').then(r => r.json());
setUsers(data);…
32.8s710 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
## Code Review
This function works for the happy path, but it has several issues around error handling, retries, and readability. Here's a breakdown.
### 🐛 Bugs & Correctness Issues
| # | Issue | Why It Matters |
|---|-------|----------------|
| 1 | `except:` with no exception type | Swallows `KeyboardInterrupt`, `SystemExit`, and *everything else* (typos, `MemoryError`). You lose visibility into real failures. |
| 2 | Retries on every non‑200, including `4xx` | A `404` or `401` will never succeed by retrying — it just wastes time and rate-limit budget. |
| 3 | `if item["active"] == True` | Both linters (PEP 8 E712) and Python idiom prefer `if item["active"]:`. |
| 4 | `item["active"]` (…
33.4s3977 output tokens
Frequently asked questions
- Which is cheaper, Claude Opus 5.5 or MiniMax M3?
- Per 1M output tokens, Claude Opus 5.5 is ¥3,462 and MiniMax M3 is ¥214.44 on FastMetal (yen, before tax), so MiniMax M3 is cheaper.
- How do the context windows of Claude Opus 5.5 and MiniMax M3 compare?
- Claude Opus 5.5 takes 1,000,000 tokens; MiniMax M3 takes 1,048,576.
- Can I use Claude Opus 5.5 and MiniMax M3 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-opus-5-5" or "minimax-m3" 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 from the browser chat and the API. No monthly fee.