Kpostcode — Korean Address & Postcode Lookup for Shopify Plus Checkout
A Shopify Plus checkout extension that brings Korea's standard address-entry pattern into Shopify. Rather than typing a street address, the shopper searches the official Korean government address database API, picks the matching result, and the postcode and address fields autopopulate. Built as a Checkout UI extension — so Plus only, since Shopify restricts that surface — with a settings panel for field customisation and drag-and-drop placement. A 2026 update added address autocomplete alongside Shopify's native autocompletion. $10/month, 14-day trial. Launched 13 August 2024.
Kpostcode — Korean Address & Postcode Lookup for Shopify Plus Checkout
A Shopify Plus checkout extension that brings Korea's standard address-entry pattern into Shopify. Rather than typing a street address, the shopper searches the official Korean government address database API, picks the matching result, and the postcode and address fields autopopulate. Built as a Checkout UI extension — so Plus only, since Shopify restricts that surface — with a settings panel for field customisation and drag-and-drop placement. A 2026 update added address autocomplete alongside Shopify's native autocompletion. $10/month, 14-day trial. Launched 13 August 2024.
The brief
The challenge, and how we approached it
01
The challenge
Korean shoppers don't type addresses — they search a government database and select one. Shopify's default free-text address field is unfamiliar enough that Korean customers abandon at checkout, and the addresses that do get entered are frequently malformed for domestic couriers. The only place to fix it is the checkout, which Shopify opens to Plus stores alone.
02
Our approach
Build on the supported surface rather than around it: a Checkout UI extension calling the official Korean government address API, so results are authoritative rather than a third-party dataset. Selection writes back into Shopify's own address fields — postcode, road name, detail — so downstream fulfilment and courier handoff work unchanged. A configuration panel handles field customisation and lets the merchant drag the lookup block into position without developer involvement. The 2026 release added autocomplete and compatibility with Shopify's native address autocompletion, so the two systems coexist rather than compete. Flat $10/month, matching the app's narrow single-purpose scope.
What we built
Six capabilities shipped for Dana's Bakery
Each one solves a specific part of the brief above.
ZIP-gated shipping
Real-time validation prevents invalid ZIP purchases from entering cart
Drop architecture
Pre-staged inventory with countdown, sold-out gates, and waitlist
Gifting flow
Message cards, recipient addressing, scheduled delivery, gift wrap
Perishable inventory
Daily inventory sync with cold-chain capacity constraints
Drop-day performance
Theme architecture handles 20× traffic spikes without latency
Recurring orders
Holiday subscription flow for repeat gifters
How it ran
10 weeks build, in four stages
Every engagement runs the same four stages, so you always know what happens next and what you owe us at each one.
Stage 1
Audit and scope
We review the current theme, apps and analytics, then write a fixed-scope SOW with named deliverables and a date.
Stage 2
Design and build
Work happens in a dev store on a Git-backed workflow. You get a preview link from week one, not a reveal at the end.
Stage 3
QA and launch
Cross-browser and device QA, redirect map, analytics verification, then a launch window agreed with you rather than dropped on you.
Stage 4
Hypercare
Fourteen to sixty days of included post-launch support while real traffic finds the edge cases.
The outcome
Where Dana's Bakery landed
Conversion is up 2.1× after the PDP rebuild, AOV is up 34% year-over-year thanks to gifting upsells, and drop days are now smooth — zero downtime across 12 drops in the past year.
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★
★
★
★
★
Every drop day was a stress event before. Now they're just a Tuesday. The team built us infrastructure we can actually grow on.
FounderSeoul Commerce
Tech stack
What this project runs on
The exact platform, services and integrations behind the build.
Commerce platform
Shopify Plus
Launchpad
Shopify Functions
Online Store 2.0
Engineering
Custom ZIP validator
Growth and operations
Klaviyo
ShipBob
More case studies
Other work worth reading
Long-form studies from the same team, with the numbers behind them.
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