Zero-Friction Authentication: Building a Sign-In Flow Users Actually Love

The Science Behind Our Sign In Form: Zero-Friction Authentication at PostNitro

After logging into thousands of apps over my 10 years as a developer, I've seen every login flow imaginable. Some brilliant, most mediocre, many frustratingly bad. This is the summation of what I've learned about onboarding users the right way.

The Philosophy: Get Users to Value, Fast

Here's the thing about PostNitro - people come to our platform to create carousel posts for LinkedIn and Instagram. They don't come to fill out organization setup forms, create workspaces, or configure team settings. Every second spent on authentication and setup is a second they're not doing what they actually came here for.

So we built our sign-in flow around a simple principle: automate everything, let users customize later.

When you sign in to PostNitro.ai for the first time, we automatically:

• Create a new user account
• Assign an organization to that user
• Create a workspace in that organization where all their data lives
• Drop them directly into the carousel editor

No onboarding steps. Just log in and start creating.

The Evolution: From Google Auth to OTP

Phase 1: Google Authentication Only

We launched with AuthJS and Google Authentication as our only sign-in option. The reasoning was simple - clicks instead of typing. No password to remember, no email verification flow to build, and most importantly, no friction.

For the majority of our early users, this worked perfectly. They clicked "Sign in with Google" and within seconds they were in the editor creating their first carousel.

Phase 2: The Business Email Problem

Then we started getting feedback. Business users with email accounts that weren't linked to Google Workspace needed a way to sign in. They didn't want to use their personal Google accounts for work purposes, and many companies have policies against mixing personal and business accounts.

The solution seemed obvious: magic links. Instead of the standard username and password login (which would require verification emails, password reset flows, security considerations), we added magic link authentication. AuthJS handled this beautifully, and we shipped it quickly.

Users would enter their email, receive a link, click it, and boom - they're in. No password to remember, no verification hassle.

Phase 3: The Mysterious Consumed Links

This is where things got weird.

We started getting reports from users saying their magic links weren't working. They'd click the link and get an error saying it had already been used. But they swore they hadn't clicked it before.

At first, I thought it was user error. Maybe they were clicking twice, or their email client was prefetching links. But the pattern was too consistent.

During debugging sessions, I'd ask users to keep their email closed while we tested. Then I'd check Postmark (our email service) and see that the links were showing as opened. But here's the kicker - they were all opened in microseconds. Not human speeds.

That's when it clicked. Many business email providers have security layers that automatically open every link in incoming emails to scan for malware or phishing attempts. This protective layer was consuming our magic links before users even saw their emails.

We needed a different approach.

Phase 4: The Better Auth Migration

Magic links were dead for a significant portion of our user base. The alternative was One-Time Passwords (OTP). But AuthJS didn't support OTP.

Then something serendipitous happened - Better Auth acquired AuthJS. There was finally a clear migration path, and Better Auth had native OTP support.

I'll be honest, I was hesitant about Better Auth before the acquisition. It was a newer project, and switching authentication systems is risky. But once AuthJS beta was no longer going to be maintained, the decision was made for us.

The migration took a few days. We moved all existing users to Better Auth, kept Google Authentication, and added OTP support. Users just had to log in again - they didn't feel any disruption in their workflow.

And just like that, the business users who complained were happy again. They could use their work emails with OTP codes instead of magic links.

You can read more about the AuthJS and Better Auth merger here: AuthJS Joins Better Auth

The Technical Stack

Our authentication system runs on:

• Next.js for the frontend and API routes
• Better Auth for authentication (with Google OAuth and OTP)
• Supabase as our database
• Postmark for transactional emails (OTP delivery)

Better Auth handles all the heavy lifting - rate limiting, session management, security best practices. We don't have to worry about the nitty-gritty details of authentication security because it's already built-in.

The Organization Problem: Avoiding Setup Friction

Initially, when users logged in, they'd land directly in their PostNitro account. Simple. But as we grew, we needed to add team collaboration features. Users wanted to invite team members, share workspaces, and manage brand assets together.

This required restructuring our entire data model:

USER → ORGANIZATION → WORKSPACES[] → TEAM MEMBERS[]

Now, the "standard" SaaS onboarding flow would look like this:

1. User signs in
2. User creates an organization (enters name, details)
3. User sets up their first workspace
4. User invites team members
5. User finally starts creating carousels

That's four setup steps before they can do what they came here for. Even if we made steps 2 and 4 optional, that's still two interruption points.

We asked ourselves: is there a better way?

The answer was yes - automate it all.

The Two-Second Onboarding

Here's what happens in those two seconds between clicking "Sign in" and landing in the editor:

1. Authentication - Better Auth verifies the user's credentials (Google OAuth or OTP)
2. User Creation - If it's a new user, we create their account
3. Organization Setup - We automatically create an organization with a default name (usually derived from their email or name)
4. Workspace Creation - We create their first workspace with default settings
5. Redirect - We drop them directly into the carousel editor

All of this happens behind the scenes. No forms. No "Next" buttons. No progress bars.

The user is literally in the editor before they realize what happened.

Later, if they want to:

• Rename their organization
• Create additional workspaces
• Invite team members
• Manage brand settings

They can do all of that from the settings panel. But right now? They're creating.

The 95/5 Rule

This approach follows what I call the 95/5 rule: make assumptions that work for 95% of users, and let the 5% power users customize later.

Traditional SaaS onboarding asks you to set up everything upfront because they're worried about edge cases:

• "What if they want a specific organization name?"
• "What if they need multiple workspaces from day one?"
• "What if they want custom settings?"

But edge cases are called edge cases for a reason. Why make 100% of users go through extra steps to accommodate situations that affect maybe 5% of them?

The answer: don't.

Give 95% of users the fastest possible path to value. Let the 5% who need customization do it after they've experienced the product.

The Philosophy Behind Everything We Build

This zero-friction approach isn't just about our sign-in form. It's a philosophy that shapes everything we build at PostNitro:

Remove friction wherever possible Every click, every form field, every "Next" button is friction. If it's not absolutely necessary, cut it.

Make smart assumptions Most users want the same thing. Give them that by default. Let them change it if they're different.

Get people to value immediately The faster someone experiences the value of your product, the more likely they are to stick around. Every second of setup delays that moment.

Let power users customize later Advanced features belong in settings panels, not onboarding flows. New users don't know they need those features yet anyway.

The Results

In the last 14 days alone, 3,600 users have signed up for PostNitro. The vast majority go straight from sign-in to creating their first carousel in under a minute.

We don't get complaints about onboarding. We don't see drop-off during setup. Users just... create.

That's the goal, isn't it?

Lessons from 10 Years of Logging In

Having logged into thousands of apps over the past decade, here are the patterns I've noticed in great authentication experiences:

The Good:

• One-click social auth (Google, GitHub)
• Magic links that actually work
• OTP for business emails
• Zero setup steps after authentication
• Smart defaults everywhere

The Bad:

• Password requirements that force you to use a password manager
• Email verification flows that make you check your inbox mid-signup
• Multi-step onboarding wizards that teach you nothing
• Asking for information you could infer or set as defaults
• Progress bars that make you watch fake loading states

The Ugly:

• "Choose your plan" screens before you've tried the product
• Asking for payment information during signup
• Required fields that have nothing to do with using the product
• Onboarding tutorials that prevent you from just using the app

The Question Every Builder Should Ask

Is there a better way to do this? Do onboarding steps like these actually serve your users, or just your assumptions about what users need?

Because here's the truth: most onboarding friction exists because we're afraid of making decisions for our users. We ask them questions because we're not confident enough to assume the answers.

But assumption isn't arrogance when it's informed by understanding 95% of your users want the same thing.

The best onboarding is no onboarding at all. Just remove the barriers and let people use your product.

What friction are you eliminating in your products? I'd love to hear how other builders are thinking about authentication and onboarding. What patterns have you found that work? What anti-patterns are you avoiding?

This is part of our "Science Behind" series where we share the reasoning and evolution of design decisions at PostNitro.ai