OpenAI vs Anthropic vs Gemini APIs: developer guide
The three leading model APIs compared on models, agent tooling, free access, pricing levers and data terms for teams building AI products.
Most AI products are built on one of three model APIs: OpenAI’s, Anthropic’s or Google’s Gemini API, reached through Google AI Studio. All three offer frontier and smaller models, tool calling and agent features, and all bill per token. Choosing between them is less about a single benchmark than about model fit for your task, tooling, cost controls and data terms.
The short answer
- Choose the OpenAI API if you want OpenAI’s GPT models and the Agents SDK for building tool-using agents.
- Choose the Anthropic API for Claude models with code execution, computer use and structured outputs, plus batch and caching discounts.
- Choose the Gemini API if you want a generous free tier, multimodal models including image, video and live voice, and Google grounding.
Side by side
| OpenAI API | Anthropic API | Gemini API (AI Studio) | |
|---|---|---|---|
| Models | Current GPT family plus real-time and specialised models | Claude Haiku, Sonnet, Opus and Fable | Gemini models, plus image, video and speech models |
| Agent tooling | Agents SDK and tool calling | Tool use, code execution, computer use, JSON-schema outputs | Function calling, Search and Maps grounding, managed agents, Live API |
| Free access | Usage-based; check current offers | Usage-based | Free tier with rate limits |
| Cost levers | Per-token prices vary by model | 50% batch discount, prompt caching | Batch API at 50% lower cost, context caching |
| Cloud availability | Directly from OpenAI | Also on Amazon Bedrock and Google Cloud | Enterprise route through Google Cloud |
Free tiers and data use
Google offers a free tier for the Gemini API, but its pricing page states that content on the free tier may be used to improve Google’s products, while the paid tier excludes it. That makes the free tier ideal for prototypes and unsuitable for sensitive data. OpenAI and Anthropic bill from the first token; review each provider’s retention and training terms for the API, which differ from their consumer apps.
Controlling cost
Model choice is the biggest lever: smaller models such as Claude Haiku or lighter Gemini and GPT models cost far less per token. Beyond that, Anthropic and Google both offer batch processing at half price for work that does not need instant answers, and both cache repeated context. Pin model versions in production, because names and prices change frequently.
Building agents
Each platform now supports agents. OpenAI provides the Agents SDK. Anthropic’s API includes tools for running code, operating a browser or desktop and constraining output to a schema. Google’s Gemini API offers managed multi-turn agents, grounding with Search and Maps, and a Live API for real-time voice and video. Many teams use more than one provider and route tasks to the model that suits each.
How to decide
- Write ten representative prompts from your product, including edge cases.
- Run them on two model sizes from each provider and score the results blind.
- Calculate cost per task including caching or batch discounts where they apply.
- Check data retention and training terms for the exact tier you will use.
- Design your code so you can switch providers, for example with a provider-agnostic SDK.
OpenAI APICoding
Anthropic APICoding
Google AI StudioCoding
Mistral AICoding
Vercel AI SDKCoding
OpenRouterCodingTools to explore
Sources
Official vendor pages consulted for this analysis in October 2026. Plans, limits and features change: check the vendor’s page before you buy.
- OpenAI API: product page openai.com
- OpenAI API: pricing openai.com
- Anthropic API: product page anthropic.com
- Anthropic API: pricing docs.claude.com
- Google AI Studio: official site aistudio.google.com
- Google AI Studio: pricing ai.google.dev