OpenAI DevDay 2025: Agent Kit, Apps SDK & ChatGPT Updates

This week’s OpenAI DevDay 2025 event, held on October 6, showcased a major strategic shift for the company, positioning ChatGPT as an evolving operating system rather than a standalone service. Developers gained access to powerful new tools, including the AgentKit, Apps SDK, and Codex, alongside significant model updates like GPT-5 Pro and Sora 2 entering the API. Partnerships with companies such as Canva and Zillow now allow users to interact directly with third-party services from within the ChatGPT interface, marking a leap toward more integrated, app-like experiences.

Sam Altman wrapped up the keynote by emphasizing that artificial intelligence is becoming a primary method for human-computer interaction. He announced that GPT-5 Pro is now available through the API, offering developers enhanced reasoning capabilities and accuracy. A smaller model, gpt-realtime-mini, also debuted. In addition, Sora 2, the recently unveiled video generation model, launched in the API, enabling developers to produce high-quality, realistic video content directly within their own applications.

During a live demonstration, Romain Huet, Head of Developer Experience at OpenAI, illustrated the expanded capabilities of Codex. He used the tool to wire a camera to an Xbox 360 controller, enabling real-time panning and movement. Simultaneously, he built a voice-controlled lighting assistant that responded to verbal commands and illuminated the audience. The demo concluded with Codex generating a custom credits overlay featuring DevDay attendees, initiating a countdown, and capturing a group photo, all within minutes.

Altman also shared that Codex usage has surged tenfold since early August, driven by platform expansions and underlying model improvements. The tool is now out of research preview and generally available to all developers.

Another highlight was the introduction of AgentKit, designed to help developers build, deploy, and optimize agentic workflows. It integrates with the Responses API and includes performance evaluation features. In a timed live demo, Christina Huang from OpenAI built and shipped a functional “Session agent” and “DevDay Agent,” complete with guardrails and PII enforcement, in under five minutes. The resulting agent was published to the DevDay website with nearly a minute to spare.

Alexi Christakis demonstrated the new Apps SDK with several integrated app experiences inside ChatGPT. He launched a Coursera video directly in the chat, then interacted with its content using natural language. Next, he used the Canva app to generate multiple poster designs inline, followed by a request for ChatGPT to turn the poster into a polished pitch deck, a moment that drew audible excitement from the audience. By integrating Zillow, he filtered local property listings using simple text prompts, bypassing traditional website filters. The App SDK is now available in preview, with a developer submission process for app listings expected later this year.

Altman opened the event by outlining four key announcement areas: apps in ChatGPT, building agents, writing code, and API updates. The launch of the Apps SDK provides developers full-stack capabilities, moving beyond earlier options like GPTs and incorporating Anthropic’s Model Context Protocol. Attendees expressed enthusiasm about new monetization pathways.

The 2025 DevDay was OpenAI’s largest to date, held at Fort Mason in San Francisco with over 1,500 participants and media in attendance for the first time. The agenda included a livestreamed keynote with Sam Altman, followed by sessions with President Greg Brockman, COO Brad Lightcap, and former Apple designer Jony Ive, fueling speculation about updates to OpenAI’s rumored AI wearable device.

(Source: ZDNET)