OpenAI used DevDay 2025 to push a stack of developer-facing launches — GPT-5 Pro in the API, Sora 2 in the API, AgentKit, an Apps SDK, and Codex — then sent eight staffers onto Reddit to answer questions in real time. The message was blunt: this is infrastructure for builders, not a consumer showcase.
What's new
The headline additions are GPT-5 Pro and Sora 2 landing in the API, giving developers programmatic access to OpenAI's most capable text and video models. AgentKit is positioned as a framework for building more reliable agents, while the Apps SDK targets developers shipping directly inside ChatGPT. Codex rounds out the release, targeting code generation workflows. OpenAI posted full replay videos for anyone who missed the live announcements.
Why it matters
Putting GPT-5 Pro and Sora 2 behind an API — rather than keeping them locked to ChatGPT — is the move that actually matters here. It signals OpenAI is serious about the developer platform layer, not just the consumer product. AgentKit in particular is a direct play for the agentic workflows market where Anthropic, Google, and a growing list of open-source frameworks are all competing hard right now.
What to watch
Pricing and rate limits on GPT-5 Pro API access will determine whether this is a genuine shift or just a preview. The Apps SDK is also worth tracking — embedding third-party apps inside ChatGPT could reshape how developers think about distribution. Expect more detail to surface from the AMA thread as the team continues fielding questions throughout the day.