For API experiments, Gemini is the only one of these three with a documented ongoing free tier on selected first-party models. OpenAI and Claude are paid APIs unless a specific promotion or eligible credit programme applies. Compare the product you will actually call, not the name on a free chat app.
At a glance
| API route | What is free | Card / billing | Limits and exclusions |
|---|---|---|---|
| Gemini API | Selected models within the Free tier | Card policy not explicitly stated in the sources we checked | Limits shown per account/model in AI Studio; not every model is free |
| OpenAI API | No general sign-up credit confirmed | Paid API billing is separate from ChatGPT | Check current model prices; an OpenAI-compatible third-party API is not an OpenAI credit |
| Claude Console API | No general sign-up credit confirmed | Prepaid usage or an eligible award; startup card policy not stated | General startup cohort closed; partner-VC route conditional |
| Azure student/startup programmes | Eligible Azure credit for covered models | Students: no card; startup programme: card required | Account/subscription eligibility and model coverage apply |
| AWS Activate for Claude | Approved startup credits for eligible Bedrock usage | Paid AWS plan required | Separate AWS balance; not an Anthropic Console credit |
Gemini: selected models and account-specific limits
Google’s billing documentation says new accounts begin on the Free tier. Check the current pricing table for the exact model and your limits in AI Studio. Do not copy a limit from someone else’s account.
The Google Cloud $300 trial is a different balance, valid for 90 days. It covers eligible Google Cloud services, including Google’s own models on Agent Platform, and excludes the standalone Gemini API and partner models such as Claude. The Gemini terms distinguish paid and unpaid data-use rules and regional exceptions; review them before sending sensitive material.
OpenAI: separate API billing from ChatGPT
Check OpenAI’s API pricing and the billing view for the API account. We have not confirmed a general free sign-up credit; this does not rule out a targeted promotion for a particular account.
For eligible Azure subscriptions, Azure for Students and Microsoft for Startups describe access to Azure OpenAI models. Those are Microsoft programmes, not credit transferred to an OpenAI API account. Groq’s open-weight gpt-oss models and OpenRouter’s free variants are another option, but they are not the same service as OpenAI’s hosted API.
Claude: check availability before applying
The general Claude Startups cohort is closed. Current members retain access; eligible startups backed by a partner VC may separately receive credits for the first-party API. The Claude guide explains those steps and AWS Activate’s separate Bedrock route.
Do not assume that AWS new-account credits, Google’s $300 trial or a Claude Team subscription pay for Console API usage. Use the API directory to choose an ongoing allowance, and the rate-limit comparison to check whether it fits your workload.