There is no single right choice.
This page lists only facts verified against official documentation and does not rank model quality. All three work in ResearchGangs with your own API key.
Quick comparison
| Claude (Anthropic) | ChatGPT (OpenAI) | Gemini (Google) | |
|---|---|---|---|
| Where to get a key | Claude Console (platform.claude.com) | OpenAI Platform (platform.openai.com) | Google AI Studio (aistudio.google.com) |
| Billing model | Prepaid credits | Prepaid credits (5 USD minimum) | Free tier, or paid tier through Cloud Billing |
| Free tier | Not stated in the documentation checked | Not stated in the documentation checked | Yes, new accounts start on the Free Tier |
| Does a paid chat plan include the API? | No. Max and Team include monthly API credits | No. Billed separately from ChatGPT | Not applicable |
| API data used to improve products | See the provider's terms | Not used for training by default | Used on the free tier, not on the paid tier |
| Vietnam supported | Yes | Yes | Yes |
Worth remembering
- Chat plans (Claude Pro, ChatGPT Plus) are different from the API. You need a separate API key, billed separately.
- With Claude and ChatGPT you add credits before use. When credits run out, the API stops working.
- With Gemini you can start for free. Content sent on the free tier may be used by Google to improve its products; the paid tier is not.
- You can connect several providers and choose which account each project uses. See Connect AI to ResearchGangs.
Key guides
Official sources
- Get your Claude API key (Claude Platform Docs)
- How do I pay for my Claude API usage? (Claude Help Center)
- Supported Regions Policy (Anthropic)
- Developer quickstart (OpenAI)
- Your data (OpenAI)
- Supported countries and territories (OpenAI)
- Setting up and managing prepaid API billing (OpenAI Help Center)
- Billing (Google AI for Developers)
- Gemini Developer API pricing
- Gemini API Additional Terms of Service
- Available regions (Google AI for Developers)
Checked against the provider's documentation on 28/10/2026. Their interface may change over time.