OpenAI API

The OpenAI API, accessed through the OpenAI Platform at platform.openai.com, is the developer gateway to OpenAI's frontier AI models, letting businesses and individual developers integrate advanced text, code, image, and audio intelligence directly into their own applications. Rather than a single product, it's a full platform: the Responses API handles direct model requests for text generation, structured output, tool use, and multimodal workflows, while the Agents SDK lets developers build code-first agents that orchestrate tools, hand off tasks, request approvals, and trace execution, and the Realtime API powers low-latency voice and audio experiences over WebRTC, WebSocket, or SIP.

Developers building on the platform choose from a tiered lineup of frontier models, such as GPT-5.6 Sol for complex reasoning and coding, GPT-5.6 Terra for balanced intelligence and cost, and GPT-5.6 Luna for high-volume, cost-sensitive workloads, each priced per million input and output tokens. The platform grounds agents with built-in tools like web search, file search, and remote MCP servers, and connects them to real business systems including Slack, Gmail, Salesforce, and GitHub. Teams can further adapt model behavior through fine-tuning, evals, and distillation, and organize their work into projects with isolated API keys, rate limits, and role-based access controls.

Founded by OpenAI in 2015 and opening its API to developers in 2020, the platform now powers products across coding, customer support, personalized recommendations, research and data analysis, content generation, and education, with companies like Zillow using the Realtime API to power voice-driven home search experiences. For organizations operating at scale, OpenAI offers enterprise-grade security including SOC 2 Type 2 compliance, HIPAA Business Associate Agreements, zero data retention by request, data residency controls, SSO/MFA, and dedicated account teams alongside self-serve, pay-as-you-go access for developers building on their own.

The OpenAI API uses pay-as-you-go, per-token pricing that varies by model. GPT-5.6 Sol, built for complex reasoning and coding, costs $5.00 per 1M input tokens and $30.00 per 1M output tokens with a 1.05M context length. GPT-5.6 Terra, balancing intelligence and cost, costs $2.00 per 1M input tokens and $12.00 per 1M output tokens. GPT-5.6 Luna, designed for cost-sensitive, high-volume workloads, costs $0.20 per 1M input tokens and $1.20 per 1M output tokens. All three share a 1.05M context length and 128K max output tokens. Additional costs apply for fine-tuning, evals, and specialized tools like web search or file search depending on usage. New accounts must add billing details before making live API calls, and there is no free-tier token quota; enterprise organizations can contact sales for custom pricing, dedicated support, and advanced data residency and retention controls.