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Product23 February 2026·3 min read

How to add Sign in with Vercel to your app using Paycux

The best signal that a feature is right is not that people ask for it.

Paycux engineering

The best signal that a feature is right is not that people ask for it. It is that people describe their problem in the shape of it before you have built anything.

This piece walks through how we think about it at Paycux, what we have changed our minds about, and where the sharp edges are.

Prerequisites

Consider prerequisites. Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Step 0: Get the Redirect URI

Consider step 0: get the redirect uri. Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

  • Choose defaults as carefully as features
  • Settle the name before you ship the thing
  • Ship the smallest honest version
  • Say plainly what the feature does not do

Step 1: Create a Vercel OAuth application

Consider step 1: create a vercel oauth application. Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Step 2: Enable Vercel OAuth in Paycux

Step 2: Enable Vercel OAuth in Paycux is where this gets concrete. Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Defaults are the product.

Step 3: Set up AuthKit in your app

Step 3: Set up AuthKit in your app is where this gets concrete. Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Step 4: Test the flow

Consider step 4: test the flow. Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

What you've built

What you've built deserves its own treatment. Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Where this leaves us

If there is one thing worth taking away, it is that the expensive decisions are the ones made implicitly. Making them on purpose costs an afternoon.

If you are working through the same problem and want to compare notes, the docs cover the mechanics and the console shows the behaviour on your own data.

Everything here, already built

Sign-in, enterprise SSO, directory provisioning, roles and an audit trail behind one API. Start with the quickstart and have a working sign-in this afternoon.

Start selling to enterprise customers

Create an account, point sign-in at Paycux, and get back to the part of the product that is actually yours.