Gemini 3.5 Flash vs gpt-oss-20b
Pricing, context window and real answers (September 2026)
Gemini 3.5 Flash (Google) and gpt-oss-20b (OpenAI), 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
 Gemini 3.5 Flash |  gpt-oss-20b | |
|---|---|---|
| Provider | OpenAI | |
| Input (per 1M tokens) | ¥268.05 | ¥5.36 |
| Output (per 1M tokens) | ¥1,608.3 | ¥25.02 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,072 | ¥18 |
| Context window | 1,048,576 tokens | 131,072 tokens |
| Release date | 5/19/2026 | 8/5/2025 |
| Input modalities | text, image, video, file, audio | text |
| Throughput (p50) | — | — |
| Arena · overall | #25 · ELO 1,478 | #252 · ELO 1,317 |
| Arena · Japanese | #19 · ELO 1,468 | #179 · ELO 1,256 |
| Arena · coding | #55 · ELO 1,506 | #232 · ELO 1,369 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, gpt-oss-20b: ¥25.02 per 1M output tokens, 98% less than Gemini 3.5 Flash.
- On the Overall arena board, Gemini 3.5 Flash ranks higher (#25; gpt-oss-20b is #252).
- On the Japanese arena board, Gemini 3.5 Flash ranks higher (#19; gpt-oss-20b is #179).
- On the Coding arena board, Gemini 3.5 Flash ranks higher (#55; gpt-oss-20b is #232).
- For long documents, Gemini 3.5 Flash: a 1,048,576-token context window against 131,072 for gpt-oss-20b.
- 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.
Gemini 3.5 Flash
There are **3** 'r's in the word "strawberry".
Here is the step-by-step breakdown of how to count them:
1. **Break the word down into its individual letters:**
* 1st letter: **s**
* 2nd letter: **t**
* 3rd letter: **r** (First 'r')
* 4th letter: **a**
* 5th letter: **w**
* 6th letter: **b**
* 7th letter: **e**
* 8th letter: **r** (Second 'r')
* 9th letter: **r** (Third 'r')
* 10th letter: **y**
2. **Identify and count only the 'r's:**
* s - t - **r** (1) - a - w - b - e - **r** (2) - **r** (3) - y
By counting them as we go through the word, we find a total of **3** 'r's.
4.8s601 output tokens
gpt-oss-20b
**Count of ‘r’ in “strawberry”: 3**
---
### Step‑by‑step reasoning
1. **Write out the word in individual letters**
```
s t r a w b e r r y
```
2. **Identify each ‘r’**
- The first ‘r’: appears after the “t” → **r**
- The second ‘r’: appears in the part “berry” → **r**
- The third ‘r’: the next letter after that → **r**
3. **Verify there are no more letters left**
The remaining letters are “b”, “e”, “y”, none of which are “r”.
4. **Count the identified ‘r’s**
1 (first) + 1 (second) + 1 (third) = **3**
---
### Quick recap
- Word: **strawberry**
- Letters containing “r”: positions 3, 8, and 9.
- Total count: **3**.
11.6s371 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…
Gemini 3.5 Flash
### What is causing this error?
The error `TypeError: Cannot read properties of undefined (reading 'map')` means that your `UserList` component is trying to call `.map()` on the `users` variable, but **`users` is currently `undefined`**.
This usually happens for one of two reasons:
1. **The parent component forgot to pass the prop:** `<UserList />` was rendered without the `users` attribute.
2. **Asynchronous data fetching:** The parent component fetches the users from an API, but the API request hasn't finished yet when the component first renders, so `users` starts as `undefined`.
---
### How to fix it
Here are the three best ways to fix this, depending on how you want your UI to beh…
11.2s1524 output tokens
gpt-oss-20b
### Why does the error happen?
`users.map(...)` can only run when **`users` is an array**.
The stack trace shows that the crash happens on line 12 of `UserList.js`, which is the
exact spot where the code tries to call `.map`.
The value that is being passed to `UserList` (or the initial value that the parent
creates) is **`undefined`** (or it could be `null`/`{}`). When JavaScript tries to
read `users.map`, it throws:
```
TypeError: Cannot read properties of undefined (reading 'map')
```
Typical reasons for this are:
1. The parent component **didn’t pass the `users` prop** at all.
2. The parent passed it but the value was **`undefined` / `null`** because data
hasn’t been loaded ye…
11.4s1303 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):…
Gemini 3.5 Flash
Here is a review of your function, followed by two improved versions (one that keeps your structure but makes it Pythonic, and one production-ready version that uses industry best practices).
---
### Key Areas for Improvement
1. **Imports inside the function:** `import requests` and `import time` should be at the top of the file (PEP 8). Keeping them inside the function slows down execution if the function is called repeatedly.
2. **Bare `except:` clause:** Using `except:` without specifying an exception type is a major anti-pattern. It catches things you don't want to catch, like `KeyboardInterrupt` (Ctrl+C) or `SystemExit`. It should target `requests.RequestException`.
3. **Implicit `Tr…
19.7s2975 output tokens
gpt-oss-20b
Below is a quick “code‑review” style list that touches the three axes you asked for – **readability**, **performance**, and **best practices**.
After the bullet‑list I’ll paste a refactored version that incorporates the most common fixes.
---
## 1. Readability
| Issue | Why it hurts | Quick fix |
|-------|--------------|-----------|
| **Imports inside the function** | Every call recompiles the import tables and makes the module’s top‑level slower. | Move `import requests` and `import time` to the module’s global header. |
| **Bare `except:`** | Catches *everything* (KeyboardInterrupt, SystemExit, MemoryError, etc.) and swallows useful tracebacks. | Catch only the expected network-relate…
24.6s2267 output tokens
Frequently asked questions
- Which is cheaper, Gemini 3.5 Flash or gpt-oss-20b?
- Per 1M output tokens, Gemini 3.5 Flash is ¥1,608.3 and gpt-oss-20b is ¥25.02 on FastMetal (yen, before tax), so gpt-oss-20b is cheaper.
- How do the context windows of Gemini 3.5 Flash and gpt-oss-20b compare?
- Gemini 3.5 Flash takes 1,048,576 tokens; gpt-oss-20b takes 131,072.
- Which ranks higher, Gemini 3.5 Flash or gpt-oss-20b?
- Gemini 3.5 Flash ranks higher on the public arena (Gemini 3.5 Flash #19, gpt-oss-20b #179). Ranks move as the leaderboard updates.
- Can I use Gemini 3.5 Flash and gpt-oss-20b with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.5-flash" or "gpt-oss-20b" 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 Gemini 3.5 Flash and gpt-oss-20b from the browser chat and the API. No monthly fee.