OpenAI API
Free tier
Limited trial credits (expire)
Credit card required
Yes (after trial)
Cheapest model
GPT 4o mini ($0.15/$0.60)
Free flagship access
No
Free search grounding
No
Anthropic API
Free tier
No free tier
Credit card required
Yes
Cheapest model
Haiku 3.5 ($0.80/$4.00)
Free flagship access
No
Free search grounding
No
Google AI Studio
Free tier
Ongoing free tokens, no expiration
Credit card required
No
Cheapest model
Flash Lite ($0.075/$0.30)
Free flagship access
Yes (2.5 Pro, rate limited)
Free search grounding
Yes (500 RPD)
Zero cost to start building
Google AI Studio is the only major AI API platform where you can go from zero to a working prototype without entering payment information. The free tier includes capable models like Gemini 2.5 Pro and Gemini 2.5 Flash with enough capacity for real development work.