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King Checkout Validation

Checkout & address validation for VAT, phone, and order limits

by Gordon Kihn · Launched: March 2024 · Free plan available.

5.0 (17) on Shopify Built for Shopify
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Block checkout with address, phone, order limit validation, and more

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About King Checkout Validation

Use checkout and address validation to check shipping/billing addresses, block PO boxes, require house or apartment numbers, and validate postcode/ZIP, email, and VAT/tax ID. Run phone validation at checkout. Build custom validation rules with keywords, regex validation, field validation, cart amount, quantity, weight, products, customer tags, B2B status, country, and shipping-zone conditions. Shoppers see localized errors so they can fix issues and continue checkout. Run checkout and address validation for shipping and billing addresses Use PO box validation and detect missing house/apartment numbers Checkout email validation, postcode/ZIP, VAT/tax ID, and phone Create order limits by amount, quantity, weight, product, customer, or country Use keyword, regex validation, field validation, and localized errors Show more Show less

Last verified: July 16, 2026 · Fresh

App details

Developer
Gordon Kihn
Pricing
Free plan available
Launched
March 2024
Rating
5.0 (17) on Shopify

Key features

  • Free of charge for development store
  • Creating rules in test status
  • Live chat, email support
  • Missing house number, apartment, suite
  • Missing VAT number Checker
Integrations with:

Checkout, Shopify Admin

3 plans · starts free · 7-day free trial

Free

Free

Basic

$4.99/month

Premium

$9.99/month

Plans and prices as listed on the Shopify App Store.

Ratings & reviews

based on 21 Shopify App Store reviews

Use the arrows to read individual reviews

Excellent product and excellent support. Many of our customers use freight-forwarding service and will forget to enter their Suite numbers in shipping addres causing the orders to fail, be sent back. Result is no sale and loss of initial shipping charge. No longer have this problem thats to King checkout
— Nemechek Protocol
The app itself is feature-rich and has been very helpful for managing shipping restrictions and preventing problematic orders. It's easy to use, flexible, and backed by a team that truly cares about its users.
— Even Realities Global
Support was responsive and quickly implemented support for validating a new early access Shopify field to collect a required ID number in certain countries. Really appreciate the fast turnaround.
— Retro
Exactly what we we're looking for, since we can't use the checkout blocks as we're not on Shopify Plus.
— The English Hatter
App funktioniert wunderbar, der Support ist schnell und zielführend, haben 2 Funktionen angefragt, die innerhalb kürzester Zeit einprogrammiert wurden (Rules für billing address, war vorher nur für shipping verfügbar).
— Tennis-Point
Great support and service. Gordon is a major help!
— Juvenon
Incredible service. Had the app for 5 minutes, and needed a custom feature/rule which wasn't included. Gordon from support created my new feature within 30 min.
— Colorful Standard
Very nice app - and especially very good and fast support. Thanks.
— Pilgrim
Danke für die Hilfe vom Support, macht bis jetzt einen guten Eindruck. :)
— Aqua-Birne
This app really saved us. We have an integration with SAP, and some fields have character limits that can’t be changed. This app solved that issue, and we also used it to block sending orders to certain islands via ZIP code rules — which works perfectly. I highly recommend this app. We’re running it on eight stores now.
— Gorilla Sports
This is a fantastic product and the developer is extremely responsive and helpful! Great app!
— Stur Drinks
Great app for controlling the checkout process with custom rules! We mainly use it to block specific ZIP codes and set character limits in fields before the data gets pushed to Shopify — and it works exactly as needed. What really stands out is the support team. When we first ran into an issue with ZIP code blocking, they quickly developed a new feature that supports both prefix and suffix rules....
— GS-DEV-Stage
Great app and best support!
— alberoshop.it | Arreda la tua tavola
He is an exceptional developer—truly the best. When it came to the new Shopify field, he resolved it immediately. His expertise and efficiency are truly remarkable. Once again, I would like to express my deepest gratitude for your support and dedication. Your contributions have been invaluable, and I hold your work in the highest regard.
— VIVAIA Korea
Created a new functionality, the day after reaching out on chat for advise on how to setup a feature, and testing the initial solution.
— A.Kjærbede
The app does its job smoothly and the support team is very quick to answer inquires and to fix issues. Gordon was a great help with the problems we have encountered.
— Simona's Luxury at Home
Very happy with the app for now! We installed it and works really easy. Also very quick customer service for any question!
— Nozi
Very good app for checkout validation, and the support team is very responsive.
— Flying Tiger Copenhagen
Great support from support team, they resolve any issue related to app.
— Tasva
Gordon helped me very fast with solving an issue i had with the checkout. Thank you so much and i deff. recommend this app.
— Cape Town Origins

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