FastMetal

Model comparison

DeepSeek V4 Flash vs Kimi K3.1 Pro

Pricing, context window and real answers (October 2026)

DeepSeek V4 Flash (DeepSeek) and Kimi K3.1 Pro (Moonshot), 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

deepseek logoDeepSeek V4 Flashmoonshotai logoKimi K3.1 Pro
ProviderDeepSeekMoonshot
Input (per 1M tokens)$0.095$2.11
Output (per 1M tokens)$0.1899$10.55
Typical cost (1,000 in + 500 out tokens × 1,000 calls)$0.1899$7.39
Context window1,048,576 tokens1,048,576 tokens
Release date4/24/202610/23/2026
Input modalitiestexttext, image, video
Throughput (p50)40 tokens/s (n=27)—
Arena · overall#105 · ELO 1,436Unranked
Arena · Japanese#91 · ELO 1,399Unranked
Arena · coding#106 · ELO 1,484Unranked

Prices are FastMetal's rates, before tax.

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-22; category names mapped and ratings rounded by FastMetal.

Which should you pick?

  • On price, DeepSeek V4 Flash: $0.1899 per 1M output tokens, 98% less than Kimi K3.1 Pro.
  • 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.

DeepSeek V4 Flash

The word "strawberry" is spelled as s-t-r-a-w-b-e-r-r-y. I go through each letter: s (no), t (no), r (yes, first), a (no), w (no), b (no), e (no), r (yes, second), r (yes, third), y (no). Thus, there are three 'r's.
3.9s251 output tokens

Kimi K3.1 Pro

There are **3** ‘r’s in **“strawberry.”** 1. Write out each letter: **s – t – r – a – w – b – e – r – r – y** 2. Locate the ‘r’s: positions **3, 8, and 9**. 3. Count them: **1 + 1 + 1 = 3**.
11.3s

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…

DeepSeek V4 Flash

The error occurs because `users` is `undefined` when the component tries to call `.map()` on it. ## Why this happens Your component expects `users` to be an array, but it's receiving `undefined` as a prop. This typically happens when: 1. The parent component doesn't pass the `users` prop 2. The data fetching hasn't completed yet (async data loading) 3. The API response is missing the expected data structure ## How to fix it ### Option 1: Default prop value (Recommended for initial state) ```jsx function UserList({ users = [] }) { return ( <ul> {users.map(user => <li key={user.id}>{user.name}</li>)} </ul> ); } ``` ### Option 2: Guard clause (More explicit) ```jsx func…
6.3s422 output tokens

Kimi K3.1 Pro

## What's causing the error The error means `users` is `undefined` when the component renders, and you can't call `.map()` on `undefined`. The component itself is fine — the problem is that whatever renders `<UserList />` either isn't passing the prop, or is passing a value that isn't an array yet. The most common cause is **async data fetching**: the parent renders `UserList` before the data has loaded. ```jsx function App() { const [users, setUsers] = useState(); // ❌ undefined on first render useEffect(() => { fetch('/api/users') .then(res => res.json()) .then(setUsers); }, []); return <UserList users={users} />; // users is undefined here initially } ``` On…
36.3s

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):…

DeepSeek V4 Flash

Here's a comprehensive review with suggested improvements: ## Issues Identified: 1. **Import at wrong location** - Imports inside functions are inefficient and non-standard 2. **Bare `except:` clause** - Catches all exceptions including `KeyboardInterrupt`, `SystemExit` 3. **Missing error handling granularity** - Should distinguish between retryable and non-retryable errors 4. **Duplicate sleep logic** - Same sleep in `else` and `except` blocks 5. **Unnecessary variable** - `data` is only used once 6. **Inefficient list building** - Manual loop instead of list comprehension 7. **Hardcoded error message** - No logging or error context 8. **Missing type hints** - No type annotations 9. **Fun…
12.6s987 output tokens

Kimi K3.1 Pro

The timeout and bounded retry loop are good starting points. The biggest issue is that failures—and even programming errors—are silently converted into retries and then `[]`. ### Suggested improvements - **Avoid bare `except:`**. It catches `KeyboardInterrupt`, `KeyError`, JSON/schema errors, and other bugs. Retry only expected transient network failures; let malformed responses fail visibly. - **Use a deliberate retry policy**. Retrying `401`, `403`, or `404` usually wastes time. Retry only transient statuses, use exponential backoff, and avoid sleeping after the final attempt. - **Do not use `[]` for both failure and no results**. Prefer raising the final exception so callers can disting…
560.2s

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Frequently asked questions

Which is cheaper, DeepSeek V4 Flash or Kimi K3.1 Pro?
Per 1M output tokens, DeepSeek V4 Flash is $0.1899 and Kimi K3.1 Pro is $10.55 on FastMetal (US dollars, before tax), so DeepSeek V4 Flash is cheaper.
How do the context windows of DeepSeek V4 Flash and Kimi K3.1 Pro compare?
DeepSeek V4 Flash takes 1,048,576 tokens; Kimi K3.1 Pro takes 1,048,576.
Can I use DeepSeek V4 Flash and Kimi K3.1 Pro with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "deepseek-v4-flash" or "kimi-k3.1-pro" 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 DeepSeek V4 Flash and Kimi K3.1 Pro from the browser chat and the API. No monthly fee.

Create a free accountTry DeepSeek V4 Flash in chatTry Kimi K3.1 Pro in chat

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