Sites and the Next Generation of Web Apps | DevDay 2026
Use Codex and Sites to turn a spreadsheet into a full-stack app, keep its data fresh with scheduled tasks, and personalize it through user plugins.
- Prompt Codex to turn a spreadsheet into a site with useful views, filters, and links to supporting documents.
- Use plugins and scheduled tasks to refresh a site's SQLite database without redeploying its code.
- Expose custom annotations and WebMCP tools so people and agents can edit and use your app.
Live demos show the build, scheduled updates, personalized connectors, and agent-powered interactions. · Best for: Developers and teams building internal tools or public web apps with AI agents.
The presenters demonstrate Sites as a way to build full-stack apps from prompts, keep them updated with scheduled tasks, personalize them using each visitor's connectors, and let people and agents interact with the app.
What Sites are for0:20
- Sites are used for interactive presentations, spreadsheet replacements, internal tools, prototypes, and public ideas.
- The presenters describe Sites as connected to context, plugins, and agents.
Build and refresh a launch-tracking app2:23
- The demo prompts Codex to turn a spreadsheet into a launch radar with milestones, attention items, filters, list, board, and calendar views, and links to launch assets.
- A scheduled task uses Google Drive launch briefs to keep the site updated each morning.
- Sites include a SQLite database, which scheduled tasks can update directly without a redeploy.
Permissions and personalized data5:29
- Sites have built-in authentication with Sign-in with ChatGPT; new sites are private by default.
- Visitors can bring their own plugins, so the same site can show each user their own data.
- The demo connects Linear with read and write access, showing tickets and saving a status change.
Collaborative editing with annotations12:04
- In-app browser annotations let users select elements and request changes through Codex.
- Developers can add custom annotations, controls, and suggested prompts in a site's HTML to make editing easier.
Agent interactions with WebMCP14:22
- The GIF Studio demo uses the OpenAI image API and an environment variable for its API key.
- WebMCP lets a site expose tools that an agent can use instead of navigating by clicking through the interface.
- The agent searches Slack for a recipient's interests, suggests catalog items, updates the app, and drafts a personal message.
Wrap-up19:13
- The presenters describe Sites as full-stack apps with authentication and a database, as well as support for plugins and agent interactions.
- They recommend considering custom annotations and WebMCP when building apps for people working with agents.
Step by step
- Ask Codex to turn a spreadsheet into a site, specifying the views, filters, key information, and linked documents you need.
- Ask Codex to keep the site current using documents from a connected plugin and a schedule such as daily.
- Set access for the site, then add the relevant plugin and permissions if visitors need personalized data or write access.
- Add custom annotations to make app elements easier to select and edit with Codex.
- Expose WebMCP tools for app actions that agents should perform directly.
Tools & resources mentioned
- Sites — host full-stack web apps with built-in authentication and a SQLite database.
- Codex — build and update sites from prompts.
- Google Drive plugin — retrieve the launch briefs used to refresh the demo site.
- Linear plugin — display and update a visitor's assigned tickets.
- Slack — search messages for information used to personalize the GIF recommendations.
- WebMCP — expose site tools for agents to query and act on an app.
- OpenAI image API — generate the GIF Studio box design; the demo supplies an API key through an environment variable.
Notes are AI-generated from the video's transcript and may miss nuance.