Sign in with ChatGPT stopped being only a login button at OpenAI DevDay on September 29, 2026. Eligible Plus and Pro users can now bring ChatGPT plan usage into participating third-party apps, not just identity. For India and USA agency delivery teams, that change hits product UX, enterprise SSO policy, partner billing, and security consent in the same sprint.

I am Nitin Kumar, Lead Project Coordinator at Debugged Pro. I help agencies ship ChatGPT-connected products without surprise token bills or broken SSO. This guide sticks to reporting from The New Stack, The Star, OpenAI's Sign in with ChatGPT docs, and the DevDay 2026 notes, then turns those facts into a practical playbook.

If your clients ask whether "Continue with ChatGPT" means free AI inside your app, you need a clear answer before launch week.

OpenAI DevDay 2026 recap art for Sign in with ChatGPT agency guide — Feature image: Official OpenAI DevDay 2026 recap artwork. Credit: OpenAI.

What Changed for Sign in with ChatGPT at DevDay 2026

Identity-only Sign in with ChatGPT rolled earlier. In July 2026, The New Stack reported beta partners that included Airtable, GitLab, HubSpot, Notion, Supabase, and Vercel. At that stage, partners received identity details for account creation and login. Plan usage was not the main story.

At DevDay 2026, OpenAI expanded the product so eligible ChatGPT Plus and Pro subscribers can use their existing plan allowance for AI requests inside participating third-party apps. Sam Altman told developers on stage that this makes products easier to try because users already pay for AI, and partners need not cover token costs to get those users going, according to The New Stack coverage by Paul Sawers.

The Star's October 4, 2026 report framed the same move as part of a wider ChatGPT apps platform: users can discover and run software inside the chatbot, while Sign in with ChatGPT carries identity and usage allowance into partners such as Devin, Notion, and Vercel.

Identity-Only Versus ChatGPT Plan Usage

Agencies should treat these as two products under one brand label.

Identity scopes

OpenAI's official Sign in with ChatGPT quickstart states that identity scopes can give your app a stable account id, name, email, and profile picture. Those scopes do not grant ChatGPT conversations or OpenAI API keys. The flow uses OpenID Connect with PKCE. Your application still owns account creation, enterprise SSO policy, sessions, and authorization.

Plan usage scopes

ChatGPT plan usage needs separate Responses API scopes that the user must authorize. Eligible requests draw from ChatGPT Work and Codex usage already included in the subscriber plan. Identity login alone does not equal included model usage.

Commercial Sign in with ChatGPT is a limited trial with selected partners. Plan usage is available to open-source partners and selected private clients, per both the SIWC docs and the DevDay 2026 page.

Button label guidance is specific: use Continue with ChatGPT, place it with other sign-in options, and keep comparable visual weight.

ChatGPT branding for Sign in with ChatGPT identity and plan usage — Body image: Official ChatGPT branding card from OpenAI Developers. Credit: OpenAI.

Launch Partners Named for Plan Usage

The New Stack listed about sixteen launch partners for ChatGPT plan usage, with OpenAI saying it will expand quickly. Named services include OpenCode, OpenClaw, Pi, T3, Hyperagent, Hermes Agent, Vorflux, Amp, Dactyl, Kilo Code, Warp, Conductor, Devin, Notion, and Vercel, with Lovable coming soon.

That mix matters for agency roadmaps. You will see coding agents, IDE-adjacent tools, and productivity platforms in the same partner set. Clients will compare your product against Devin, Warp, Notion, and Vercel experiences where ChatGPT plan usage already works.

The Star also notes an enterprise marketplace with more than 30 partners, including Adobe, Figma, Salesforce, and ServiceNow, plus Dots agents that can access 4,000-plus apps. OpenAI has not announced an app-store-style billing or revenue share yet. Budget models that assume store revenue from ChatGPT apps still need a Plan B.

Partner Billing Surprises Agencies Must Call Out

Plan usage reduces friction. It does not erase every partner credit meter.

Dactyl is the clearest published example from The New Stack. Connecting ChatGPT covers the agent that interprets requests and writes code. Compile steps, icons, assets, and publish still consume Dactyl credits. Users do not supply an OpenAI API key; auth runs through the ChatGPT account. Earlier, Dactyl limited plan sharing to personal ChatGPT Pro on Builder or higher, while Plus and Business could still sign in for identity only. The DevDay announcement broadened plan usage to both Plus and Pro.

Users can set weekly caps per app in ChatGPT settings. When a cap is hit, included usage stops. It does not auto-switch to partner billing, according to The New Stack. That is a support ticket waiting to happen if your UX hides the difference between included ChatGPT usage and your own credits.

Agency checklist for billing clarity:

Split line items in pricing pages: ChatGPT-included AI vs partner credits.
Surface weekly caps in onboarding copy and empty states.
Log stop events when included usage ends so support can explain them.
Do not imply that Sign in with ChatGPT covers compile, storage, or publish fees.
Document Plus vs Pro eligibility for each partner integration you ship.

When Agencies Should Use Identity-Only

Identity-only still wins in several delivery patterns common across India and USA accounts.

Enterprise SSO is mandatory. OpenAI docs say that when your product requires enterprise single sign-on, guide the person to that existing sign-in experience. ChatGPT identity can sit beside SSO for consumer tiers, not replace IdP policy.
You already meter AI on your own stack. If the client pays through your credits or a direct OpenAI API key, identity login alone may be enough for conversion.
Commercial SIWC access is still limited. If you are not in the selected partner trial, do not promise plan usage in sales decks.
Data boundaries are strict. Identity scopes avoid conversation and API-key access. That helps security reviews that reject broad AI entitlements.

For product teams building ChatGPT-connected experiences, Debugged Pro's ChatGPT development services cover identity flows, plugin work, and delivery architecture for India and USA clients.

When Plan Usage Is the Better Fit

Plan usage fits when your value depends on AI requests and you want users to try before they fund a second AI bill.

Open-source clients and selected private apps already have a documented path for Responses API scopes.
Coding agents and developer tools compete with partners that already advertise "runs on your ChatGPT subscription."
Consumer and prosumer funnels where Plus and Pro users expect portable allowance.
Pilot programs where the client refuses another token invoice during evaluation.

Pair plan usage with hard product limits. Caps stop included usage; they do not invent partner revenue. Your finance model still needs paid tiers for non-AI work, storage, seats, or overage after the ChatGPT allowance ends.

If the roadmap includes multi-agent workflows beyond sign-in, see Debugged Pro's agentic AI development for delivery patterns that keep human approval gates and cost controls in place.

Body image: Official OpenAI brand artwork used with ChatGPT platform coverage. Credit: OpenAI.

Security, Consent, and Enterprise SSO Notes

Keep the consent story boring and complete.

Separate scopes in UX copy. Identity first. Responses API / plan usage only after a clear second explain.
PKCE and backend exchange. Follow the OpenID Connect steps: auth code to your callback, backend token exchange, verify the OpenAI ID token, then create your own session.
App owns the session. Sign in with ChatGPT supplies verified OpenAI identity. It does not replace your RBAC, tenant isolation, or audit logs.
Enterprise SSO still rules for many USA and India enterprise buyers. Offer ChatGPT continue for eligible tiers, then route workspace admins to SAML/OIDC IdP flows.
Plugin permissions stay separate from the OpenAI identity token when you ship ChatGPT plugins.

Security reviewers will ask what you store: account id, email, name, picture, refresh tokens, and any Responses access tokens. Answer with retention periods and rotation. Do not claim access to ChatGPT chat history; the docs say identity scopes do not grant conversations.

India and USA Agency Delivery Playbook

Use this sequence on active accounts.

Map the ask. Is the client buying login conversion, included AI usage, or both?
Confirm partner status. Limited commercial trial vs open-source / selected private clients.
Write two user journeys. Identity-only success path and plan-usage success path, including cap exhaustion.
Align SSO. Document when ChatGPT continue is blocked by enterprise policy.
Price the non-AI remainder. Compile, assets, seats, storage, support.
Train support. Cap hits do not auto-bill partners; users may think the app is broken.
Watch the marketplace story. The Star notes 30-plus enterprise partners and no announced app-store revenue share. Do not sell ChatGPT store economics that OpenAI has not published.
Revisit weekly. OpenAI said plan-usage partners will expand quickly after the initial set.

India delivery squads often need audit-ready screenshots of consent and scope screens for client InfoSec. USA enterprise buyers often ask for IdP precedence and token handling diagrams. One shared checklist with region-specific artifacts keeps both happy.

Related reading on ChatGPT product surface area for agencies: ChatGPT Space agency guide for India and USA teams. For broader delivery consulting, start at software development consulting.

Key Takeaways

Sign in with ChatGPT now covers identity and, for eligible Plus and Pro users, ChatGPT plan usage in participating apps after DevDay 2026 (Sept 29, 2026).
Identity-only beta partners in July 2026 included Airtable, GitLab, HubSpot, Notion, Supabase, and Vercel.
Plan usage launch partners named by The New Stack / OpenAI include OpenCode, OpenClaw, Pi, T3, Hyperagent, Hermes Agent, Vorflux, Amp, Dactyl, Kilo Code, Warp, Conductor, Devin, Notion, and Vercel, with Lovable coming soon.
Identity scopes give account id, name, email, and picture, not conversations or API keys. Plan usage needs separate Responses API scopes.
Label the button Continue with ChatGPT. Your app still owns accounts, SSO policy, and sessions.
Weekly per-app caps stop included usage; they do not auto-switch to partner billing.
Dactyl shows partner credits can still apply for compile, icons, assets, and publish.
The Star notes ChatGPT apps inside the chatbot, enterprise marketplace partners, Dots access to 4,000-plus apps, and no announced app-store revenue share.

FAQ: Sign in with ChatGPT for Agency Teams

These answers restate reported facts and the delivery notes above.

Nitin Kumar is Lead Project Coordinator at Debugged Pro. He helps software agencies and delivery teams in India and the USA plan ChatGPT integrations, agentic workflows, and launch-ready identity and billing UX.