Shopify & eCommerce Developer

I buildShopify stores,themes & apps.

Custom themes and Liquid, theme customization, app integrations and custom apps. Plus eCommerce development beyond Shopify.

Will Dang

What I can do for you

your store

How I work

The same six steps on every project, from a small theme tweak to a full app.

  1. 01

    Find the real problem

    I ask what you need and why, then say it back in one sentence so we agree.

    You getA clear problem statement
  2. 02

    Collect the data

    Store data, logs, analytics and what your team sees. Facts before guesses.

    You getThe facts, in plain words
  3. 03

    Measure the impact

    Who it affects, what it costs you, how urgent it is. That decides what goes first.

    You getA priority list
  4. 04

    Plan it

    Steps, timeline and risks, written down. You approve it before I start building.

    You getA plan you sign off on
  5. 05

    Build and keep you posted

    Small releases, tested before they go live. A short update every day, good news or bad.

    You getDaily progress updates
  6. 06

    Support and warranty

    I stay after launch. If something I built breaks, I fix it.

    You getSupport after handover

Products I've built

Four apps on the Shopify App Store, used by merchants every day. Some I built alone, some as a core team member.

All work and details →

Work

Everything I've worked on, by product. Open a case to see the plan, the steps and the numbers.

PageFly

Shopify page builder. Its elements and scripts run on merchants' live storefronts.

Solo★ 4.9 · 5,926 reviews on the App Store ↗
Storefront speed

Every PageFly page at 90+ on Lighthouse

90+Lighthouse score
open for details ↓
Problem
PageFly elements and scripts slowed down merchants' storefronts.
What I did
  • Optimized 10+ PageFly elements.
  • Built a lazy-load mechanism so elements load only when they are needed.
  • Made fonts and scripts load faster.
Result
90+ Lighthouse on all PageFly pages
Lazy loading · font loading · script loading · Lighthouse
Migration · solo

Hundreds of storefront scripts moved to a theme app extension

0bugs at release
open for details ↓
Problem
Storefront scripts had to move to a theme app extension. They run on merchants' live stores, so one bug could reach millions of shoppers.
What I did
  • Worked alone on the whole migration, hundreds of files.
  • Moved every storefront script into the theme app extension.
Result
Zero bugs at release
Theme app extension · storefront scripts · Liquid

Joy Subscriptions

Subscribe-and-save for Shopify. I built the core features with the team.

Core team★ 4.9 · 467 reviews on the App Store ↗
  • Subscribe-and-save options on product pages
  • Customer portal inside Shopify customer accounts
  • Cancellation flow that keeps customers who want to leave
  • Failed payment recovery
  • Build-a-box and product bundles
  • Volume and tiered discounts
  • 11 Shopify Flow triggers
  • Subscriptions sold at the POS
  • Analytics and activity log
  • Bulk edits and migration from other apps
  • Custom SMTP and storefront translations
  • Shopify Sidekick tools
Theme app extension · Customer account extensions · Checkout · POS · Flow · Functions (cart transform, discounts) · Admin actions · Sidekick · Webhooks

Avada Email Marketing

Email campaigns and automation for Shopify stores. I planned and built these alone.

Solo · planned & built★ 4.8 · 819 reviews on the App Store ↗
Database migration · cost

From MongoDB to Firestore and BigQuery

$2k/mosaved
open for the plan ↓
Problem
MongoDB cost about $2,000 a month to hold 45M contacts, 21M orders and 27M ordered products.
My plan
Firestore as the main database, BigQuery as the data warehouse for reports. I wrote the plan alone.
Result
$2k a month saved
Zero bugs at deploy.
MongoDB · Firestore · BigQuery · data migration
Provider migration · cost

Email sending moved from Mailgun to Amazon SES

$3k/mosaved
open for the plan ↓
Problem
Mailgun was expensive, and moving to SES carelessly could get the new account suspended.
My plan
Use 30 days of real sending data from 239 shops to decide who moves first, and keep a fallback. I wrote the plan alone.
What I did
  • Found 2 shops sent 82% of the default volume, with 28.9% and 25.1% bounce rates, and kept them off the new account.
  • Added a whitelist, daily caps per domain and automatic fallback to Mailgun.
  • Copied 125k blocked addresses to SES first, with 0 errors in 124,836 writes.
  • Moved 359 of 359 shops off a blacklisted sending domain, delivery steady (73.8% → 73.0%).
Result
$3k a month saved
Zero bugs at deploy.
Amazon SES · Mailgun · deliverability · DNS · idempotent jobs
Speed & cost

Report page: from $149 a day to under $1

~330×cheaper per day
open for the plan ↓
Problem
One bot kept opening merchants' lifetime campaign reports. Each card scanned whole tables, so one day cost $149. A normal day costs $1–4.
My plan
Fix it in 3 layers, release behind switches I can turn off, and prove the numbers match before switching.
What I did
  • Clustered tables, so a query only reads the shop it needs.
  • Charts read a nightly daily summary instead of raw events.
  • Report cards read live counters.
  • Compared old and new numbers on 100 campaigns, then watched cost through a month-end.
Result
38 GB → 161 MB per query
$149/day → $0.30–0.45/day
91 of 100 campaigns matched exactly, total drift −0.73%.
BigQuery · clustering · rollup tables · feature flags

Avada PDF Invoice

Invoices and business documents for Shopify orders. I built core features with the team.

Core team★ 4.9 · 712 reviews on the App Store ↗
  • Invoices, packing slips, refunds, credit notes, pro formas and quotes from orders
  • 77 templates and a branded template editor
  • Bulk print and email from Shopify's Orders page
  • The same tools for draft orders
  • Automatic invoice emails with editable templates
  • Customers download invoices from their account, past orders too
  • Invoice printing at the POS
  • Invoice download on the storefront
  • B2B: companies, payment terms, reminders, combined payments
  • EU VAT and EN 16931 e-invoices
  • Documents in 104 languages
  • Public API and Shopify Sidekick tools
Admin print actions · Admin links · Customer account extensions · POS · Theme app extension · Sidekick · Webhooks

Need a store, a theme, or an app?

Tell me what you need. I reply within a day with questions or a first plan.