> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pillsoftware.com/llms.txt
> Use this file to discover all available pages before exploring further.

# In-checkout validation

> Prevent invalid shipping addresses before checkout completion with house number checks, name checks, email typo checks, regex rules, and field limits.

## In-checkout validation

<Frame>
  <img src="https://mintcdn.com/pillsoftwaregmbh/Q0a27EjzB0_v1EwX/images/in-checkout-validation-thumbnail.jpg?fit=max&auto=format&n=Q0a27EjzB0_v1EwX&q=85&s=115fcf7c89eb6f999ad1bfe1f26fb768" alt="In-checkout validation tutorial thumbnail" width="2560" height="1440" data-path="images/in-checkout-validation-thumbnail.jpg" />
</Frame>

<Card title="Watch tutorial" icon="circle-play" href="https://youtu.be/izI_pivZr_c">
  Open the in-checkout setup video on YouTube.
</Card>

### What this does

AddressPill validates the shipping address while the customer is still in checkout.

### Why this matters

You catch issues before payment. This reduces bad addresses entering your fulfillment pipeline.

### What you can control

* Require house number
* Check duplicate first/last name
* Detect special characters in address fields
* Detect common email typos
* Block with custom regex pattern
* Set field length limits for address, name, and company
* Choose rule behavior: **warning** or **block checkout**

### Where to configure

Open [In-checkout settings](/settings/in-checkout-validation-rules).

## FAQ

### Which issues can in-checkout validation catch?

It can catch missing house numbers, duplicate names, special characters, email typos, regex matches, and field length violations.

### Should I use warning or block mode?

Use warning mode first for safe rollout, then enable block mode for critical rules.

### Where do I configure in-checkout rules?

In **Settings > In-checkout validation**.