The 2025 edition of OpenAI DevDay, held on October 6th at Fort Mason in San Francisco, marked a major inflection point in the evolution of AI. With over 1,500 developers attending in person and thousands tuning in worldwide, the event delivered on its promise of unveiling OpenAI’s bold vision for the next phase of intelligent systems.

A Platform Shift: ChatGPT as an Operating System

The most headline-grabbing announcement was the introduction of apps inside ChatGPT. OpenAI launched a new SDK allowing developers to build and integrate third-party apps directly within ChatGPT. This move effectively transforms ChatGPT from a conversational AI into a platform ecosystem—a kind of operating system for AI-driven productivity.

Imagine using ChatGPT to not just chat or code, but to book a trip via Expedia, analyze data in Sheets, or even order lunch—without ever leaving the chat interface. This shift positions OpenAI to compete not just with other AI labs, but also with traditional app marketplaces like those of Apple and Google.

The AgentKit Suite: Building True AI Agents

Another major highlight was the unveiling of AgentKit, a comprehensive suite of tools designed to empower developers to build advanced AI agents. The suite includes:

• Agent Builder – A framework for creating, training, and managing intelligent agents capable of performing multi-step tasks autonomously.

• ChatKit – Tools and APIs for crafting conversational experiences that integrate seamlessly with ChatGPT and external systems.

• Guardrails – A safety and compliance layer ensuring responsible agent behavior, aligning with policy and ethical constraints.

• Evals – A benchmarking and evaluation toolkit that allows developers to test, compare, and improve model performance across use cases.

Together, these components make it easier to design robust, safe, and context-aware agents that can act independently while staying aligned with user intent.

Codex and Developer Tools: Leveling Up AI for Builders

OpenAI also unveiled updates to the Codex model, the foundation for code generation in ChatGPT. The upgraded version brings faster responses, deeper contextual understanding, and tighter IDE integration. Developers can now build, test, and deploy AI-assisted code more seamlessly, bridging the gap between conversation and creation.

Workshops during DevDay demonstrated new ways to embed OpenAI’s APIs into mobile, web, and enterprise stacks. The overall message was clear: OpenAI wants to make it radically easier to build with AI.

Enterprise Evolution: AI Meets Business

In a notable pivot, OpenAI announced expanded enterprise offerings and partnerships. With new integrations for collaboration tools, CRM systems, and internal data pipelines, the company is targeting enterprise-scale adoption. Executives from several partner companies joined the stage to discuss how they’re embedding ChatGPT and OpenAI APIs across their organizations.

This move signals OpenAI’s intention to become not just a research leader but a foundational layer for modern business operations.

The Big Picture: From Models to Ecosystems

The 2025 DevDay showcased a clear strategic evolution. OpenAI is no longer just a model provider—it’s becoming a platform enabler and ecosystem architect. By opening ChatGPT to third-party apps and autonomous agents, OpenAI is laying the groundwork for what many are calling the Agentic Internet—a world where intelligent systems act as intermediaries between humans and the web.

Final Thoughts

OpenAI DevDay 2025 wasn’t just about new products; it was about redefining the AI-human relationship. From autonomous agents to embedded apps, the company’s direction points toward a world where conversations evolve into actions—and where AI is not just a tool, but a collaborator.

As Sam Altman put it during his keynote: “We’re building the next layer of computing—one that understands you, helps you, and acts for you.”

If DevDay 2023 was the beginning of generative AI’s mainstream rise, DevDay 2025 marks the beginning of its agentic age.