Claude Sonnet 5.5 vs Hy4
Pricing, context window and real answers (November 2026)
Claude Sonnet 5.5 (Anthropic) and Hy4 (Tencent), 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 5.5 |  Hy4 | |
|---|---|---|
| Provider | Anthropic | Tencent |
| Input (per 1M tokens) | $2.11 | $0.8799 |
| Output (per 1M tokens) | $10.55 | $2.64 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | $7.39 | $2.20 |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Release date | 9/28/2026 | 11/4/2026 |
| Input modalities | text, image, file | text |
| Throughput (p50) | 306 tokens/s (n=28) | — |
| Arena · overall | #31 · ELO 1,477 | Unranked |
| Arena · Japanese | #30 · ELO 1,465 | Unranked |
| Arena · coding | #24 · ELO 1,529 | Unranked |
Prices are FastMetal's rates, before tax.
Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-28; category names mapped and ratings rounded by FastMetal.
Which should you pick?
- On price, Hy4: $2.64 per 1M output tokens, 75% less than Claude Sonnet 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 Sonnet 5.5
Let me go through the word letter by letter.
**strawberry**
| Position | Letter |
|---|---|
| 1 | s |
| 2 | t |
| 3 | **r** ← 1st |
| 4 | a |
| 5 | w |
| 6 | b |
| 7 | e |
| 8 | **r** ← 2nd |
| 9 | **r** ← 3rd |
| 10 | y |
**Step-by-step reasoning:**
1. I split the word into individual letters: s-t-r-a-w-b-e-r-r-y (10 letters total).
2. I checked each letter for 'r'.
3. The first 'r' is in position 3, in "str…".
4. The second and third 'r's are in positions 8 and 9, in the "…rry" ending.
**Answer: There are 3 r's in "strawberry".**
A common mistake is to see "berry" as having only one 'r' (or to treat the double-r as a single letter), which leads to the incorrect answer of 2.
3.1s332 output tokens
Hy4
The word **“strawberry”** is spelled:
**s t r a w b e r r y**
Step by step:
1. Check each letter: s, t, **r**, a, w, b, e, **r**, **r**, y
2. Mark the **r**’s: one after **t**, and two near the end before **y**.
3. Count them: 1 + 1 + 1 = **3**
So, there are **3** ‘r’s in **“strawberry”**.
4.2s343 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 5.5
## Cause
`users` is `undefined` when the component renders, so `users.map(...)` throws. This happens when:
1. **The parent doesn't pass the prop**, or passes it under a different name (e.g. `<UserList data={x} />` or a typo like `user=`).
2. **The data loads asynchronously.** On the first render, the state or fetch result hasn't arrived yet.
3. **The value is wrong.** For example, the API returns `{ users: [...] }` and you passed the whole object, or you're reading a property that doesn't exist (`response.data.users` vs `response.users`).
## Fixes
### 1. Default value (simplest)
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{use…
6.7s824 output tokens
Hy4
The error is caused by this line:
```js
{users.map(user => <li key={user.id}>{user.name}</li>)}
```
At render time, `users` is `undefined`. Since `.map()` only exists on arrays, JavaScript tries to read `map` from `undefined` and throws:
```txt
Cannot read properties of undefined (reading 'map')
```
Even though this is in a Node.js app, this specific error is happening during React rendering, likely server-side rendering or a Node-based build/render process.
Common causes:
1. The parent component is not passing `users`.
2. The prop name is misspelled.
3. `users` comes from async data and is `undefined` on the first render.
4. Your API returns something like `{ users: [...] }`, but you…
20.3s1951 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 5.5
# Code Review
## Main Issues
### 1. Bare `except:` hides bugs (most important)
It catches everything, including `KeyboardInterrupt` and `SystemExit`. It also wraps your parsing logic, so a missing `"active"` key (`KeyError`) or bad JSON is treated as a network failure, retried 3 times with sleeps, and then silently becomes `[]`. Catch only `requests.RequestException`, and keep parsing outside the `try`.
### 2. Silent failure
Returning `[]` after all retries fails is indistinguishable from "the server returned no active items." Callers can't tell whether something went wrong. Raise an exception (or at least log) once retries are exhausted.
### 3. Retry logic
- It sleeps after the final at…
20.9s3003 output tokens
Hy4
Here are the main improvement areas, followed by a possible rewrite.
## Key issues
### Readability / style
- Move imports to the top of the module.
- Use descriptive names: `response` instead of `r`, `attempt` instead of `i`.
- `if item["active"] == True:` should be `if item.get("active") is True:` or simply `if item.get("active"):`, depending on intent.
- The filtering loop can be a list comprehension.
- Add type hints and a docstring.
### Performance
- Repeated imports are cached by Python, so not a major cost, but top-level imports are cleaner.
- Avoid sleeping after the final failed attempt.
- Use `requests.Session` for connection pooling if this function may be called repeatedly or i…
110.2s10761 output tokens
Frequently asked questions
- Which is cheaper, Claude Sonnet 5.5 or Hy4?
- Per 1M output tokens, Claude Sonnet 5.5 is $10.55 and Hy4 is $2.64 on FastMetal (US dollars, before tax), so Hy4 is cheaper.
- How do the context windows of Claude Sonnet 5.5 and Hy4 compare?
- Claude Sonnet 5.5 takes 1,000,000 tokens; Hy4 takes 1,000,000.
- Can I use Claude Sonnet 5.5 and Hy4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-sonnet-5-5" or "hy4" 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 5.5 and Hy4 from the browser chat and the API. No monthly fee.