Replatform a Legacy Application | NUUN Digital Solutions

WHAT'S INCLUDED

Discovery and assessment. Current-state audit, technical debt map, and modernization roadmap.
Architecture and stack selection. Headless vs. monolith, build vs. buy, and integration topology.
UX research and design. Current-state analytics review, new-experience design, and journey mapping.
Engineering build. Modern stack (typically Next.js/React + headless APIs; or commercetools/Shopify Plus for commerce).
Data migration. Content, customer, order, and analytics data migration with validation protocols.
SEO preservation. 301 mapping, pre-migration SEO audit, parallel-environment monitoring, and post-launch index rehab.
Performance and accessibility. Core Web Vitals targets and WCAG 2.2 AA compliance baked in.
Cutover plan. Staged deployment with rollback windows and zero-downtime cutover where feasible.
Post-launch care. 90-day stabilization and optimization window built into the program.

PLATFORMS WE'VE SHIPPED

Commerce: Shopify Plus, commercetools, BigCommerce, custom headless.
CMS: Contentful, Sanity, Strapi, Prismic, WordPress (headless).
SaaS re-architecture: Multi-tenant and single-tenant, cloud-native and hybrid.
Enterprise portals: customer, partner, and employee portals.
Learning and member platforms: student, member, and subscriber experiences.

WHEN THIS SOLUTION FITS

Legacy stacks throttling product velocity or customer experience.
Technical debt compounding to the point of strategic constraint.
Replatforming to enable a new business model (headless commerce, API-first, AI integration).
Post-acquisition consolidation of multiple platforms.

WHEN IT DOES NOT FIT

Incremental improvements to an otherwise healthy platform — use our Software & Product Development practice directly.
Green-field builds — engage our Software & Product Development practice for a from-scratch approach.

HOW THE PROGRAM RUNS

Discover (months 1–2). Audit, technical-debt map, UX research on current experience, and architecture decision.
Plan (months 2–3). Migration plan, SEO and data strategy, performance budget, and cutover strategy.
Design (months 2–4). UX and UI design, component library, and accessibility review.
Build (months 3–9). Engineering build, content migration, integration work, and QA.
Migrate and launch (months 8–12). Staged cutover with SEO preservation and rollback windows.
Stabilize (months 12–15). Post-launch care, optimization, and (where applicable) decommissioning of legacy systems.

WHAT YOU'LL GET

A modernization plan — architecture, data, SEO, and cutover decisions documented.
A new platform — built, tested, and deployed with WCAG 2.2 AA and Core Web Vitals targets met.
A migration audit — SEO, data, and traffic preserved with evidence (rankings, index coverage, data integrity).
A stabilization period — 90 days of post-launch care with defined SLAs.
A decommissioning plan — for the legacy system, including data retention and archive strategy.

SELECTED WORK

Confidential retailer — Headless commerce migration → page speed up [X]%, conversion up [X]%, zero SEO regression. Read case →
SaaS client — Re-architecture → deployment frequency [X]× higher; platform-modernization savings [X]% annual run-rate. Read case →
Anonymized — member portal — Portal rebuild → member engagement up [X]%, support-ticket volume down [X]%. Read case →

SOURCES & FURTHER READING

Software & Product Development practice
Design practice
Retail & E-commerce industry page
Core Web Vitals — https://web.dev/vitals/
WCAG 2.2 — https://www.w3.org/TR/WCAG22/

FAQ.

Can you do zero-downtime cutover?

Often yes. Depends on data, dependencies, and payment integrations. We scope the cutover plan with the team and are transparent about where scheduled downtime is required.

How do you handle data migration integrity?

Validation protocols at every stage — row-count checks, sample integrity checks, referential integrity validation, and a full data-reconciliation report before decommissioning legacy systems.

What about performance and accessibility?

Core Web Vitals targets (LCP, CLS, INP) and WCAG 2.2 AA compliance are baseline deliverables. Performance and accessibility aren't optimization passes; they're budgets the build is tested against.

Can we keep our existing team involved in the replatform?

Yes — and we recommend it. Your team has institutional knowledge; ours has modernization discipline. Co-delivery models (NUUN leading architecture and migration, client team leading domain logic) work well.

How do you preserve SEO authority through a replatform?

We inventory every ranking URL on the legacy site, map it one-to-one to a post-launch URL, publish 301 redirects at cutover, and monitor Search Console for crawl and ranking drift for 90 days. SEO preservation is its own workstream, not a checklist at the end.

Replatform without the regret.