The one-line answer: ship email + Google as your baseline, add Apple if you have an iOS app with any social login (Apple's rules require it), and add ChatGPT only if your users genuinely live inside ChatGPT — because unlike the other three, ChatGPT-as-login is a distribution bet, not a UX tweak. The rest of this piece is why.

On August 2, 2026, OpenAI launched Sign in with ChatGPT in beta with six partners — Airtable, GitLab, HubSpot, Notion, Supabase, and Vercel (Tech Times). Suddenly the login menu has a fourth option, and the reflex is to treat them all as interchangeable buttons. They are not. Each one carries different costs, obligations, and data, and picking wrong can get your iOS app rejected or your signup funnel quietly leaking.

Sign in with Google — the default, and why#

If you add exactly one social button, make it Google. It has the widest reach of any provider, a mature and well-documented OpenID Connect implementation, no cost, and instant recognition — users click it without thinking. There is no distribution upside (nobody discovers your product through the Google button) and you are handing Google one more touchpoint on your users, but as the lowest-friction way to authenticate the largest pool of people, it is the safe baseline. Pair it with plain email-and-password as the always-available fallback and you have covered the majority of real users.

Sign in with Apple — often not your choice#

Here is the rule most teams learn the hard way: App Store Review Guideline 4.8 requires that if your iOS app offers any third-party or social login — Google, Facebook, and now ChatGPT all count — you must also offer an equivalent privacy-focused option, and Sign in with Apple satisfies it (Apple). So the moment you add a Google or ChatGPT button to an iOS build, Apple's button stops being optional. Web-only apps are exempt.

Two operational catches come with it:

It also costs an Apple Developer Program membership (~$99/yr) — which you already pay if you are shipping to the App Store.

Sign in with ChatGPT — the only one that is a growth channel#

This is the button that is genuinely new, and the mistake is to evaluate it as an SSO convenience. It is one, but that is not the point. The other three buttons make login faster; ChatGPT can make signup originate — a user can begin adopting your product from inside ChatGPT and Codex, where hundreds of millions of people already spend their day. That is a distribution surface disguised as a login button, and we make the full strategic case in why ChatGPT-as-login is really about distribution.

The upside is real only if your users are ChatGPT-native — developers, builders, people with a ChatGPT tab always open. For a general consumer app or a non-technical business buyer, the distribution value is roughly zero, and you would be taking on a beta dependency for no gain. Two constraints make that dependency concrete: it is a beta with a fixed launch-partner list, and enterprise admins can disable it organization-wide, so a button your user had last week can disappear. It can never be your only login.

When you do add it, the build is short — a standard OIDC authorization-code flow with PKCE. We wrote the step-by-step implementation with code.

The decision, compressed#

Think of it as three independent yes/no questions, not a single pick:

  1. Google + email? Yes, almost always. This is your baseline.
  2. Apple? Yes if you have an iOS app with any other social login — you are required to. Otherwise optional.
  3. ChatGPT? Yes only if your users already live in ChatGPT. Then instrument signup origin so you can see whether the distribution bet actually paid off, and keep it as one option among several — never the only door.

The buttons look alike in the UI. Underneath, one is a safe default, one is a compliance obligation with a name-capture trap, and one is a distribution wager on a two-day-old beta. Treat them that way and you will add the right ones — and only the right ones.