OpenAI DevDay 2025 Summary - AgentKit and App Integration Deep Dive¶

What You'll Learn

Five major announcements from OpenAI DevDay 2025 How to start building AI agents with AgentKit Steps to integrate apps within ChatGPT

On October 6, 2025, OpenAI DevDay in San Francisco unveiled a new era of AI development. With 800 million weekly ChatGPT users as the foundation, the evolution of development tools now enables individual developers to build enterprise-level AI applications.

Target Audience

Mid-level engineers considering AI agent implementation
Developers looking to integrate ChatGPT into their services
Technical leaders wanting to leverage OpenAI's latest tools

Key Points¶

Understand the five major DevDay 2025 announcements
Evaluate AgentKit implementation feasibility
Learn how to integrate ChatGPT into your services

OpenAI DevDay 2025's Explosive Growth¶

Growth by Numbers¶

CEO Sam Altman's keynote revealed OpenAI's remarkable growth:

Metric	2023	2025	Growth
Weekly Users	100M	800M	8x
Developers	2M	4M	2x
API Processing	0.3B tokens/min	8B tokens/min	~27x

Five new tools were announced to support this growth.

Five Major Announcements from OpenAI DevDay 2025¶

Overview¶

Announcement	Release Type	Primary Use
AgentKit	Beta	AI agent building
Apps SDK	Preview	ChatGPT app development
Codex	General Availability	Coding assistance
ChatKit	Generally Available	Chat UI embedding
Connector Registry	Beta	Data integration management

Important

Apps SDK currently available outside EU only. Review terms of service before production deployment.

AgentKit Transforms AI Agent Development¶

8-Minute Agent Build Demonstration¶

The highlight of OpenAI DevDay 2025 was engineer Christina Huang's live demonstration. She built a DevDay attendee Q&A agent in just 8 minutes using AgentKit.

Four Core AgentKit Features¶

Agent BuilderChatKitEvals for AgentsConnector Registry

Design workflows with drag-and-drop. Place nodes for conditionals, loops, and data transformations. Supports preview runs, inline eval configuration, and full versioning.

Provides embeddable chat UI. Supports brand design customization and integrates into websites or apps with just a few lines of code.

Measure agent performance. Enables step-by-step trace recording, dataset evaluation, and automated prompt optimization. Supports third-party model evaluation.

Centrally manage integrations with popular platforms like Dropbox, Google Drive, Microsoft Teams, and SharePoint. Control security and permissions through admin dashboard.

Getting Started¶

# AgentKit SDK basic example
from agents import Agent, Runner

agent = Agent(
    name="Support Agent",
    instructions="Answer customer questions"
)

result = Runner.run_sync(
    agent,
    "How do I return Product A?"
)
print(result.final_output)

Pro Tips

Starting with Agent Builder's pre-built templates (customer support, data analysis, etc.) reduces design time by 80%.

AgentKit Integration Examples (Click to expand)

Ramp: Built a purchasing agent from blank canvas in hours. Automated expense approval process, reducing processing time by 90%.

Box: Implemented internal data search agent. Maintains permission management while instantly extracting information from 1,000+ documents.

HubSpot: Enhanced Breeze AI tool with AgentKit. Improved customer inquiry response quality, increasing first-contact resolution by 40%.

AgentKit Availability and Pricing¶

Feature	Status	Pricing
Agent Builder	Beta	Included in standard API pricing
ChatKit	Generally Available	Included in standard API pricing
Evals for Agents	Generally Available	Included in standard API pricing
Connector Registry	Beta (select customers)	Included in Enterprise/Edu plans

Running Apps Directly Inside ChatGPT¶

Apps SDK Innovation¶

OpenAI DevDay 2025 announced the Apps SDK based on Model Context Protocol (MCP). This enables direct operation of apps like Spotify, Canva, Figma, Coursera, Booking.com, Zillow, and Expedia inside ChatGPT.

Implementation Flow

Create MCP server and connect data sources
Build UI components following Apps SDK design guidelines
Test in ChatGPT using Developer Mode
Submit for app review (starting later this year)

Reference Information

DoorDash, Instacart, Uber, AllTrails planning support. Apps SDK details available in OpenAI developer documentation (open source).

User Experience Transformation¶

Previously apps launched individually. With Apps SDK, simply say "Spotify, create Friday party playlist" and the app auto-launches. Processing begins with ChatGPT context awareness.

Apps SDK Technical Features¶

MCP Compliant: Based on open standards, works on other platforms
Custom Code: Developers define interface and chat logic with own code
Direct Backend Connection: Securely connects to data sources, retrieves real-time data

Supported Plans and Regions¶

Plan	Available	Region Restriction
Free	○	Outside EU
Go	○	Outside EU
Plus	○	Outside EU
Pro	○	Outside EU

Codex General Availability Speeds Development 10x¶

From Research Preview to Production¶

OpenAI DevDay 2025 announced Codex general availability. Features GPT-5-Codex model with high SWE-bench Verified scores.

Three New Features

1. Slack Integration¶

Request code generation directly from team channels. Simply tag @Codex to understand conversation context, select appropriate environment, and complete tasks.

# Slack usage example
@Codex Add unit tests for this function

2. Codex SDK¶

Enables embedding into custom workflows. Integrate GPT-5-Codex capabilities with just a few lines of code.

// Codex SDK usage example (TypeScript)
import { CodexClient } from '@openai/codex-sdk';

const client = new CodexClient();
const result = await client.generate({
  prompt: 'Implement state management with React Hooks',
  language: 'typescript',
  context: 'Consider existing component structure'
});

3. Admin Dashboard¶

Enables usage analysis, permission control, environment management, and code review quality tracking. Available on Business, Edu, and Enterprise plans.

Codex Plan Support¶

Plan	Slack Integration	SDK	Admin Dashboard
Plus	○	○	×
Pro	○	○	×
Business	○	○	○
Edu	○	○	○
Enterprise	○	○	○

Enterprise Adoption Cases (Click to expand)

Cisco: Completed large-scale Codex deployment. Thousands of developers use in enterprise environment, reducing code review time by 60%.

Duolingo: Educational content development speed increased 3x. Create new language course prototypes in ⅓ the previous time.

Rakuten: Leveraged for Japanese code comment auto-generation. Legacy code documentation dramatically streamlined.

Features Developers Can Use Now¶

Free Tier Options¶

AgentKit: ChatKit and Evals generally available to all developers
Apps SDK: Preview testing available (outside EU)
Codex: Available on ChatGPT Plus and above

Pricing (API)¶

AgentKit and Apps SDK included in standard API pricing. OpenAI DevDay 2025 reconfirmed existing GPT-5 pricing.

Model	Input	Output	Primary Use
GPT-5	$1.25/M tokens	$10/M tokens	Advanced reasoning
GPT-5 mini	$0.25/M tokens	$2/M tokens	Lightweight tasks
GPT-5 nano	$0.05/M tokens	$0.40/M tokens	Low-cost high-volume

Cost Optimization

Prompt caching enables 90% cost reduction for repeated queries.

OpenAI's Growth Signals AI Development Democratization¶

Individual Developers Achieve Enterprise Quality¶

OpenAI DevDay 2025 announcements dramatically lowered AI development barriers. AgentKit and Apps SDK make CEO Altman's words reality: "development that took months now completes in minutes."

Three Key DevDay 2025 Messages¶

Agent Development Democratization: Build practical agents in 8 minutes with AgentKit
Platform Strategy Acceleration: Access 800M user market in ChatGPT with Apps SDK
Developer Experience Enhancement: 10x development speed with Codex GA

Summary¶

OpenAI DevDay 2025 established new AI development standards. Built on ChatGPT's 800M weekly users, AgentKit, Apps SDK, and Codex GA provide an environment where anyone from individual developers to large enterprises can build sophisticated AI applications.

Next Steps You Can Start Now:

Embed chat UI on your site with AgentKit's ChatKit
Validate existing app integration feasibility with Apps SDK Developer Mode
Measure development team productivity with Codex Slack integration

Next Steps¶

OpenAI Official Documentation - AgentKit implementation guide
Apps SDK Design Guidelines - App development procedures
Codex Getting Started Guide - SDK integration methods

Reference Links¶

Reference Information

Event Date: October 6, 2025
Location: San Francisco
Major Announcements: AgentKit, Apps SDK, Codex GA, ChatKit, Connector Registry