Overview
OpenAI API is the most widely used AI development interface globally. As of 2026, its main offerings include the **GPT-5 series (GPT-5.5 / GPT-5.4 / GPT-5 mini), GPT-Image-2 (image generation, successor to DALL·E 3), Whisper (speech recognition), TTS (text-to-speech), Sora 2 (video generation), Embeddings, and more**—a full suite of AI capabilities. Almost all mainstream AI applications use OpenAI's API at their core.
As the "infrastructure" for AI development, OpenAI API provides the most comprehensive documentation, SDKs, and developer ecosystem, making it the preferred starting point for building AI applications. It also offers multiple invocation paradigms such as ChatCompletions and Assistants, compatible with almost all AI application frameworks.
**🔥 Major Update in July 2026**: **GPT-5.6 Sol / Terra / Luna three-tier models are fully launched** (officially opened on July 10 after US government security review). The flagship Sol is priced at **$5/M input + $30/M output**, featuring the new **Ultra multi-agent mode** and max reasoning intensity, setting new records in core benchmarks for coding, biology, and cybersecurity. **Codex has been merged into the ChatGPT desktop client**, forming a three-in-one entry point (Chat / Work / Codex) alongside ChatGPT Work—OpenAI directly competes with Claude Code in the Agent programming track.
Key Features
- GPT-5 Series Large Language Models: GPT-5.5 / GPT-5.4 / GPT-5 mini covering conversation, reasoning, coding, and long-context scenarios
- Multimodal Capabilities: Full coverage of text, image, audio, and video understanding and generation
- GPT-Image-2 Image API: Image generation API successor to DALL·E 3, with significantly improved text rendering and consistency
- Sora 2 Video API: Billed per second (720p $0.10/sec, 1024p $0.50/sec), supporting native audio-video synchronization
- Whisper Speech Recognition: High-quality speech-to-text API with multilingual support
- Assistants API / Workspace Agents: Build AI assistants with memory, retrieval, and code execution capabilities; Workspace Agents for team collaboration
- Fine-tuning: Fine-tune models with your own data for customized scenarios
Use Cases
- Development of AI applications and SaaS products
- Building enterprise internal AI tools
- Chatbots and customer service systems
- Content generation and automated workflows
- AI research and model evaluation
Pros
- Outstanding model capabilities: GPT-5.5 tops multiple benchmarks in comprehensive rankings
- Most complete ecosystem: richest SDKs, documentation, and community resources
- Stable and reliable: the world's largest-scale AI API service
- Comprehensive functionality: one-stop for text + image + audio + video (Sora 2)
- Continuous iteration: fastest release of new models and features
Pricing
OpenAI API is billed per token / second / request. Reference: GPT-5.5 input ~$5/M tokens, output ~$30/M tokens; GPT-5.4 input $2.5, output $15; GPT-5 mini input ~$0.15, output ~$0.6. GPT-Image-2 is billed per image; Sora 2 video per second (720p $0.10/sec, 1024p $0.50/sec); Whisper $0.006/minute. New users receive free credits.
Summary
OpenAI API is the 'gold standard' for AI development—if you're building an AI application, it's the safest choice. The ecosystem is the most mature, models are top-tier, and documentation is the most comprehensive. The main limitation is pricing; for budget-sensitive projects, consider DeepSeek API or Google AI Studio (with free tiers) as supplements.