Claude Fable 5 vs GLM 5.1
Pricing, context window and real answers (August 2026)
Claude Fable 5 (Anthropic) and GLM 5.1 (Z.ai), 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 Fable 5 |  GLM 5.1 | |
|---|---|---|
| Provider | Anthropic | Z.ai |
| Input (per 1M tokens) | ¥1,787 | ¥250.18 |
| Output (per 1M tokens) | ¥8,935 | ¥786.28 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥6,255 | ¥643 |
| Context window | 1,000,000 tokens | 204,800 tokens |
| Release date | 6/9/2026 | 4/7/2026 |
| Input modalities | text, image, file | text |
| Arena · overall | #1 · ELO 1,507 | #41 · ELO 1,466 |
| Arena · Japanese | #2 · ELO 1,526 | #49 · ELO 1,430 |
| Arena · coding | #3 · ELO 1,551 | #36 · ELO 1,514 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GLM 5.1: ¥786.28 per 1M output tokens, 91% less than Claude Fable 5.
- On the Overall arena board, Claude Fable 5 ranks higher (#1; GLM 5.1 is #41).
- On the Japanese arena board, Claude Fable 5 ranks higher (#2; GLM 5.1 is #49).
- On the Coding arena board, Claude Fable 5 ranks higher (#3; GLM 5.1 is #36).
- For long documents, Claude Fable 5: a 1,000,000-token context window against 204,800 for GLM 5.1.
- 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 Fable 5
# Counting 'r's in "strawberry"
Let me spell out the word letter by letter and check each one:
| Position | Letter | Is it 'r'? |
|----------|--------|------------|
| 1 | s | No |
| 2 | t | No |
| 3 | **r** | ✅ Yes (1st) |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | **r** | ✅ Yes (2nd) |
| 9 | **r** | ✅ Yes (3rd) |
| 10 | y | No |
## Reasoning breakdown:
- The word "strawberry" can be split into two parts: **straw** + **berry**
- "straw" contains one 'r': st**r**aw
- "berry" contains two 'r's: be**rr**y (a double-r)
## Answer: **3**
There are **three 'r's** in "strawberry."
39.6s354 output tokens
GLM 5.1
There are **3** 'r's in the word "strawberry".
Here is the step-by-step reasoning:
1. Let's break down the word "strawberry" letter by letter: s - t - r - a - w - b - e - r - r - y
2. Now, let's check each letter one by one to see if it is an 'r':
- **s**: not an 'r'
- **t**: not an 'r'
- **r**: this is the 1st 'r'
- **a**: not an 'r'
- **w**: not an 'r'
- **b**: not an 'r'
- **e**: not an 'r'
- **r**: this is the 2nd 'r'
- **r**: this is the 3rd 'r'
- **y**: not an 'r'
3. Counting them up, there are three 'r's in total (in the 3rd, 8th, and 9th positions).
7.3s565 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 Fable 5
## Cause
The error means that when `UserList` renders, the `users` prop is `undefined`, so calling `.map()` on it fails. This typically happens for one of these reasons:
1. **The parent isn't passing the prop** (or has a typo in the prop name):
```jsx
<UserList /> // users is undefined
<UserList user={users} /> // typo: "user" instead of "users"
```
2. **Data is fetched asynchronously** — the component renders before the API call finishes, and the initial state is `undefined`:
```jsx
const [users, setUsers] = useState(); // undefined initially!
```
## Fixes
**Option 1: Default parameter value** (quick fix)
```jsx
function UserList({ users = [] }) {
re…
51.3s686 output tokens
GLM 5.1
### What is causing the error?
The error `TypeError: Cannot read properties of undefined (reading 'map')` means you are trying to call the `.map()` method on a variable that is `undefined`.
In your code, the variable is `users`. When the `UserList` component renders, the `users` prop is `undefined`, so `undefined.map()` throws an error.
### Why is `users` undefined?
This usually happens for one of two reasons:
1. **You forgot to pass the prop:** The parent component rendering `<UserList />` is not passing the `users` attribute (e.g., `<UserList />` instead of `<UserList users={myUsers} />`).
2. **Async Data Fetching:** You are fetching the users from an API. On the initial render, befor…
45.0s1680 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 Fable 5
# Code Review
Your function works, but there are several issues worth addressing. Here's a breakdown by category:
## Issues Found
### 1. **Bare `except:` clause (critical)**
This catches *everything*, including `KeyboardInterrupt`, `SystemExit`, and bugs like `KeyError` or `TypeError` in your own parsing code. You'll silently retry on programming errors and mask real problems.
### 2. **Imports inside the function**
Imports belong at module level (PEP 8). Function-level imports add overhead on each call and hide dependencies.
### 3. **`== True` comparison**
Use truthiness directly: `if item["active"]:` (PEP 8 explicitly recommends this).
### 4. **Silent failures**
Returning `[]` on fail…
38.5s1528 output tokens
GLM 5.1
Here is a review of your function, broken down by areas for improvement, followed by a refactored version of the code.
### Key Areas for Improvement
1. **Imports Inside the Function:**
Placing `import` statements inside a function is generally discouraged in Python. It slows down the function execution every time it is called, and it violates PEP 8 (the Python style guide). Imports should always be at the top of the module.
2. **Bare `except` Clause:**
Using a bare `except:` catches *everything*, including `KeyboardInterrupt` and `SystemExit`, which makes it hard to terminate a hanging program. You should catch specific exceptions (like `requests.exceptions.RequestException`).
3. *…
70.3s2854 output tokens
Frequently asked questions
- Which is cheaper, Claude Fable 5 or GLM 5.1?
- Per 1M output tokens, Claude Fable 5 is ¥8,935 and GLM 5.1 is ¥786.28 on FastMetal (yen, before tax), so GLM 5.1 is cheaper.
- How do the context windows of Claude Fable 5 and GLM 5.1 compare?
- Claude Fable 5 takes 1,000,000 tokens; GLM 5.1 takes 204,800.
- Which ranks higher, Claude Fable 5 or GLM 5.1?
- Claude Fable 5 ranks higher on the public arena (Claude Fable 5 #2, GLM 5.1 #49). Ranks move as the leaderboard updates.
- Can I use Claude Fable 5 and GLM 5.1 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-fable-5" or "glm-5.1" 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 Fable 5 and GLM 5.1 from the browser chat and the API. No monthly fee.