Case studies

Challenge

The provider collected documents by hand, calculated tax manually and passed spreadsheets around. With many countries, tax types and rules, sellers could not follow progress and operations were slow and error-prone.

Approach

• Multi-step seller applications with OCR of business licenses and IDs and e-signature via mobile QR code, cutting manual entry
• Parses the Amazon VAT Transactions Report into 7 sales categories, with tax rules for the UK and DE, FR, IT, ES, PL, CZ, NL, AT
• C79 / C88 input VAT deduction and C88 / PVA postponed accounting, with every box of the UK VAT Return generated automatically
• EPR registration and batch filing (DE/FR/ES packaging, WEEE, German batteries), authorized representatives and daily exchange rates
• Operations back office with orders, filing and tax review, role-based permissions and audit logs

Results

• Live in production, with 300+ iterations shipped in about 4 months
• About 44 business pages, 77 API endpoints and 19 data models
• 20 end-to-end tests plus a pre-release schema diff to protect tax data accuracy

Challenge

Few orders but high value, shipped by sea, air, rail or express. Order, production and logistics updates lived in group chats and spreadsheets, so overseas merchants lost track of progress.

Approach

• Four roles (admin, merchant, factory, logistics) with strict data isolation between merchants
• Order splitting and partial shipments across order → batch → delivery → shipment, with countdowns and overdue alerts
• 17TRACK API integration: automatic tracking, manual updates by logistics staff and a daily fallback sync
• SKUs generated from option combinations, inventory ledger, price history and Excel bulk import / export
• Chinese, English and French UI, order lock after receipt, human verification and request audit logs

Results

• Requirements to launch in 15 days, in 46 commits
• About 83 API endpoints, 34 front-end pages and 19 database tables
• About 25 end-to-end, integration and unit test files, with build and tests run before every push

Challenge

The site ran in Germany but its database sat in Hong Kong, so every request crossed continents. The banner video was nearly 40MB, images were not responsive, mobile first paint took tens of seconds and some admin queries hit 502s.

Approach

• Moved the database from Hong Kong to the German server, removing intercontinental query latency
• Transcoded the banner video from HEVC to H.264 720p, with a poster image and lazy loading
• Image CDN resizing with srcset and WebP, width / height placeholders, and loading on viewport entry
• Merged 17 JS files into 4 with defer, versioned static assets for long CDN caching, restored font-display: swap
• Scanned 187 pages for desktop and mobile JS errors

Results

• Homepage TTFB 17.96s → 0.94s; 10 admin requests 208.7s → 12.1s; the query that hit 502 now returns in 1.43s
• Homepage video size 38.8MB → 2.73MB (mobile)
• Homepage mobile image download 22.7MB → 241KiB (-99%)
• Lighthouse desktop (median of 3): home 56 → 88, LCP 6.5s → 1.5s; product page 44 → 91, CLS 0.287 → 0.008

Challenge

The brand runs a Shopify DTC store and its own app. Third-party loyalty apps could not connect to app accounts or the brand's back end, so member benefits were split between web and app.

Approach

• 6 sub-pages on custom sections and Alpine.js: landing page, member center, points history, coupons, account linking and more
• Points for sign-ups, email opt-ins, social follows, photo reviews, accessory purchases and birthdays, credited via callbacks
• Coupon center with claim limits, balance checks and one-click code copy
• Shopify accounts linked to app accounts via email code, so points and benefits work in both
• One codebase that switches API endpoints and language per store for multi-region sites

Results

• Live on the US and EU stores
• Built entirely in the Shopify theme, with no loyalty app subscription fees

Challenge

The range spans retail EV chargers to containerized storage that needs an inquiry. The site also had to serve the US and India, each with its own currency and domain.

Approach

• Customized Shopify's Dawn theme, with Tailwind CSS for custom components
• 4 product lines and 11 sub-categories: retail items sold directly, large storage routed to downloads and inquiries
• Shopify Markets for the US (USD) and India (INR), with a separate India domain and hreflang
• Custom carousel, tab and video sections with ARIA semantics; responsive, lazy-loaded images; font preloading
• GA4, Ahrefs analytics and WhatsApp live chat

Results

• Live in the US and India markets

Challenge

A marketing site is mostly content, but typical framework JavaScript slows first paint and interaction. Search engines and AI crawlers also need the full content without running JS.

Approach

• Qwik's resumable architecture on Vercel Edge, with almost no JavaScript run on first load
• Responsive images, deferred third-party scripts, CDN cache headers on pages and data, and link prefetching
• Site-wide JSON-LD (Organization / FAQPage / case studies) plus an llms.txt
• Sitemap generated from routes, with changed pages pushed to Baidu after each deploy

Results

• Lighthouse mobile (home, Shopify and contact pages, 3 runs each): performance 97–100
• TBT 0–10ms, CLS 0, LCP 1.4–2.6s

Challenge

Small sellers have no tax staff, and EU rules are scattered across official sites in many languages. General-purpose LLMs often get compliance questions wrong and cannot cite sources.

Approach

• Weekly crawl of 8 official sources (tax authorities of DE, FR, UK, ES, IT, NL, PL and the EU VAT Directive), MD5 incremental updates
• PostgreSQL full-text search that matches multilingual regulations to questions asked in Chinese
• Strict prompts: low temperature, required citations and effective dates, source links and a disclaimer
• SSE streaming, adapted for serverless deployment

Results

• Built in 6 days and 28 commits, usable from day one