# What Do Apps Change When They A/B Test Their Signup and Login Screens?

Source: Lazyweb Research
Published: 2026-07-07
Sample size: n=347
Tags: signup, onboarding, experiments, ux-patterns, design
HTML: https://www.lazyweb.com/research/auth-screen-ab-tests-what-do-apps-change
Markdown: https://www.lazyweb.com/research/auth-screen-ab-tests-what-do-apps-change.md

**Answer.** Lazyweb Research detected 347 before/after auth-screen experiments across 85 companies.[1] The recurring changes cluster around swapping modal logins for full-screen branded ones, adding concrete incentives to the signup form, and simplifying provider choosers — though these are observed changes with inferred rationale, not measured lift.

> Lazyweb Research detected 347 signup/login-screen experiments across 85 companies (July 2026).

## The finding

347 detected auth-screen experiments span 85 companies — an average of roughly 4 tracked auth changes per experimenting company.[1][2] These are before/after UI diffs on signup/login screens; the direction of each change is observed, but the rationale is LLM-inferred and no conversion lift is measured.[3]

## Recurring change patterns

Common observed moves on auth screens include:

- **Modal to full-screen login.** Capcut replaced a modal sign-in (TikTok/Google/Facebook) with a full-screen branded login adding phone/email/Apple; the inferred rationale is that a native-feeling full-screen flow with familiar entry points increases completion.[4]
- **Incentive on the signup form.** DoorDash swapped a marketing carousel 'Sign Up' button for a full signup form offering 'up to 40% off your first order' with name/email/mobile fields — inferred: a concrete discount on the form lowers friction versus a carousel.[5]
- **Fewer decisions.** YouTube Music replaced an account-selection UI ('Continue as' + avatar) with a single 'Sign in' button, on the inferred logic that one primary action reduces decision friction.[6]
- **Brand-first welcome.** Yelp replaced a profile-avatar card with a centered-logo welcome showing Google/Apple buttons and a prominent 'Continue with email' CTA — inferred to cut clutter and decision time.[7]

## How to apply it

If you are prioritizing an auth-screen test, the tracked field gravitates toward three levers: reduce choices to one clear primary action, make the flow full-screen and on-brand rather than a bare modal, and put a concrete incentive on the form itself.[4][5][6][7] These are the changes real apps ship most — a reasonable menu of hypotheses to test on your own screen.

## Caveats

These are observed before/after changes with inferred rationale, never measured lift — do not read them as proven wins.[3] The 347-experiment count is detection-based across 85 companies and reflects what the diff pipeline caught, not every test those apps ran.[1]

## The numbers

| Stat | Computed from |
| --- | --- |
| 347 experiments | auth_experiments_count: 347 detected auth-screen experiments |
| 85 companies (~4 per company) | auth_experiments_count: across 85 companies; 347/85≈4.1 |
| observed change + inferred rationale (no measured lift) | smallSampleWarnings: experiment learnings are LLM-inferred rationales, never measured lift |
| Capcut: modal login -> full-screen branded login | qualitative: capcut account login |
| DoorDash: carousel button -> signup form with 'up to 40% off first order' | qualitative: doordash sign up |
| YouTube Music: account-selection UI -> single 'Sign in' button | qualitative: youtube-music account login |
| Yelp: avatar card -> brand-first welcome with Google/Apple + email CTA | qualitative: yelp account login |

## Methodology

Universe: 347 detected before/after experiments on signup/login screens across 85 companies (from ~807 tracked apps). Changes observed from screenshot diffs; rationale LLM-inferred, July 2026. Caveat: no measured lift — directional patterns only.

## Sources & citations

- [1] Lazyweb Research analysis of 347 auth-screen experiments (before/after signup/login UI diffs across 85 companies), July 2026. Detected before/after UI changes on signup/login canonical screens; each has an observed change and an LLM-inferred rationale, never a measured conversion lift.

## Related questions

- [Sign Up vs Sign In: How Many Steps Does Each Take?](https://www.lazyweb.com/research/signup-vs-signin-how-many-steps)
- [How Many Auth Options Does the Typical Signup Screen Show?](https://www.lazyweb.com/research/how-many-auth-options-does-a-signup-screen-show)
- [Do Most Apps Offer Both Apple and Google Sign In, or Just One?](https://www.lazyweb.com/research/do-apps-offer-both-apple-and-google-sign-in)