PWA: Offline-First Architecture with Service Workers 

Not just "a website that works offline". It is a caching architecture with invalidation strategies, background sync, and lifecycle management. TTI under 3s on 3G, app experience without App Store.

<3s TTI on 3G
95+ Lighthouse PWA
Design PWA Architecture See Methodology
Scroll

Service Deliverables

What you receive. No ambiguity.

Offline-readiness audit and caching strategy
Service Worker with Workbox configured for your case
App Shell pattern for instant loading
Optimized Web App Manifest for installation
Push notifications (if applicable) with FCM or similar
CI pipeline with automated Lighthouse audits

Traditional Web vs Kiwop PWA

The problem with the websites you know.

Traditional web: every request goes to the internet, no connection means nothing, slow mobile loading, not installable. Kiwop PWA: Service Worker as intelligent proxy, you decide what to serve from cache, what goes to network, what to show as fallback. Users see UI in under 100ms even offline. The perception: "this app responds instantly".

sw.js
// Service Worker Caching Strategy
self.addEventListener('fetch', (event) => {
event.respondWith(
caches.match(event.request)
.then(cached => cached ||
fetch(event.request)
)
);
});
<100ms Shell
✓ Offline
95+ PWA Score

Executive Summary

What you need to know to decide.

50-70% savings vs dual native development (iOS + Android)
No App Store commissions (30%) or review process
Instant updates without waiting for approval
Shareable URL, indexable by Google, SEO maintained
Existing web conversion in weeks, not months
Main risk: limitations on iOS (storage, some APIs)

CTO / Technical Team Summary

Architecture and implementation requirements.

Service Workers mandatory (HTTPS required)
Workbox 7.x for caching strategy abstraction
App Shell pattern + content streaming
IndexedDB for complex offline persistence
Background Sync for resilient requests
Lighthouse CI in pipeline to maintain 95+ score

Is This for You?

PWA works if your audience does not need the App Store. If store discovery is critical, consider native.

Who it's for

  • Companies wanting app experience without dual native development.
  • Businesses with mobile users who do not want to download apps from stores.
  • Projects where offline or low connectivity is relevant.
  • Organizations with existing web wanting to improve mobile experience.
  • Teams with web expertise wanting to reuse knowledge (React, Vue).

Who it's not for

  • Apps requiring deep hardware access (Bluetooth LE, NFC, sensors).
  • Projects where App Store/Play Store presence is critical for discovery.
  • Experiences requiring intensive native performance (gaming, AR).
  • If your audience uses iOS and expects full native app experience.
  • Simple websites that do not benefit from offline functionality.

Caching Strategies We Implement

Workbox patterns for each use case.

01

Stale-While-Revalidate

Serves from cache immediately, updates in background. Ideal for assets that change little but need eventual freshness: blog posts, product images.

02

Cache-First + Expiration

Cache with defined TTL. For static assets: fonts, icons, versioned JS/CSS. Reduces requests, guarantees consistency with max-age.

03

Network-First + Fallback

Tries network, falls back to cache if offline. For data that must be fresh: prices, inventory. Fallback shows stale but functional data.

04

Background Sync + Queue

Failing requests are queued and retried when connected. For forms, uploads, critical actions. Real resilience.

Work Process

From traditional web to offline-first.

01

Audit and Strategy

Critical path analysis. What must work offline? What data needs sync? Caching strategy design by resource type.

02

Service Worker Architecture

Workbox configuration. App shell precaching. Runtime caching strategies. Lifecycle handling for updates.

03

Offline UI/UX

Visible connection states. Fallback pages. Queue indicators for pending actions. Edge case testing.

04

Push and Installation

Push notification setup (if applicable). Install prompt strategy. Optimized Web App Manifest. Lighthouse CI in pipeline.

Risks and How We Mitigate Them

Transparency about what can go wrong.

01

iOS Limitations

iOS has lower storage limits and some unavailable APIs. Mitigation: we design with iOS limitations as baseline, feature detection for extra capabilities on Android.

02

Stale Cache (Obsolete Data)

Aggressive caching can show old data. Mitigation: specific strategies per resource, cache versioning, UI indicating "last updated".

03

Service Worker Updates

Users can get stuck with old version. Mitigation: skipWaiting for critical updates, non-intrusive prompt for minor updates, maximum 2 reloads for new version.

04

Debugging Complexity

Service Workers add complexity layer. Mitigation: structured logging, documented DevTools workflow, caching tests in CI.

15 Years Building Web Experiences, Now Offline-First

Since 2009 we develop web applications that load fast and work well. PWAs are the natural evolution: the same web, but with superpowers. Installable, offline, notifications. No App Store, no commissions, no reviews.

15+ Years of Experience
200+ Web Projects
Client Retention 92%
Lighthouse PWA 95+

Technical Questions

What CTOs and Product Managers ask.

Does PWA Work the Same on iOS as Android?

Not the same, but good enough for most cases. iOS supports Service Workers, offline, and installation since iOS 11.3. Push notifications since iOS 16.4. Limitations: lower storage limits, no badging API. For 90% of business apps, PWA on iOS is viable.

How Do You Handle Service Worker Updates?

SkipWaiting for critical updates, prompt for non-critical updates. We version assets with hashes. CacheStorage cleanup of old versions. Users always have the latest version after maximum 2 reloads.

PWA or Native App for My Case?

PWA if: content-heavy, e-commerce, utilities, you want to avoid app stores, your audience does not install apps. Native if: you need Bluetooth LE, intensive AR, complex background processing, your audience expects an app in store.

Can I Convert My Existing SPA to PWA?

Yes. If it is already HTTPS and responsive, adding PWA capabilities is straightforward. The real work is designing what to cache, how to handle offline, and what background sync you need. Typically 2-4 weeks of development.

What Is the Typical Investment for a PWA?

Existing web conversion: €8,000-€15,000. New PWA with complex offline: €20,000-€35,000. Enterprise PWA with push, sync, and multi-tenant: €35,000+. Significantly less than dual native development (iOS + Android).

Are PWAs Indexed by Google Like Normal Websites?

Yes, PWAs are websites with superpowers. Google indexes them exactly the same. In fact, Google rewards PWAs with better Core Web Vitals (LCP, CLS) because they load faster thanks to caching.

What About Users Who Do Not Install the PWA?

It works perfectly as a normal website. Installation is optional and improves experience (fullscreen, home icon), but all caching and offline benefits work without installing.

Do You Work With International Companies?

Yes, we're a PWA development agency with 15+ years of experience. We work with clients across Europe and the Americas. Video conference meetings available.

Does Your Website Take More Than 5s to Load on 3G?

Offline-readiness audit. We analyze caching opportunities, measure TTI, and design PWA strategy. Report in 48h.

Request Audit
✓ No commitment ✓ Response in 24h ✓ Custom proposal
Last updated: February 2026

Technical
Initial Audit.

AI, security and performance. Diagnosis with phased proposal.

NDA available
Response <24h
Phased proposal

Your first meeting is with a Solutions Architect, not a salesperson.

Request diagnosis