Vibe Check: OpenAI DevDay 2025

Apps, agents, and API updates—but where's the vision that makes you dream?

October 6, 2025

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Hello from San Francisco! This is your day zero vibe check from OpenAI’s third annual DevDay.

OpenAI launched three big things:

Apps in ChatGPT with AppsSDK
AgentKit, a no-code agent builder
New models in the API: GPT-5 Pro, Sora 2, and a voice model

We held a live watch party for paid subscribers—about 50 of you attended the whole way through—and this was the reaction at the end:

Source: Every Discord.

Overall, it was a solid day on a few fronts, but it was missing some of the mind-blowing moments for developers of DevDays past. Last year’s DevDay, for example, came right after the launch of OpenAI’s first reasoning model, o1, and featured the launch of the Realtime API. In 2023, the company launched GPT-4 Turbo and custom GPTs (more on the latter below).

Maybe it’s a sign of how much the goalposts have moved, but this year’s DevDay felt a little more like OpenAI doubling down on existing opportunities than it was pushing the frontier of the future.

Let’s get into the updates.

Talk to your apps in ChatGPT

What it is: AppsSDK, a set of tools (or software developer kit) for developers to build apps inside of ChatGPT instead of as stand-alone apps.

What it does: Users can chat with apps—like Figma, Zillow, or Spotify—without ever leaving the ChatGPT interface.

Building apps in ChatGPT. Source: OpenAI (https://openai.com/index/introducing-apps-in-chatgpt/).

Our take: This is the third time that OpenAI has launched an app store concept. In March 2023, it was ChatGPT plugins, which allowed ChatGPT to call third-party apps from inside the app. They were exciting at the time, but adoption was poor.

In November 2023, it was custom GPTs, and a few months later a custom GPT app store (basically a directory of custom GPTs for anyone to use). This was significantly more popular than plugins, but OpenAI didn’t continue to update custom GPTs.

Now, it’s apps in ChatGPT, which looks like a move back to the original plugins concept. Both are effectively attempts to allow you to use third-party apps inside of the ChatGPT interface. It is the closest they’ve been to getting the app store right, but the key question is going to be performance.