(PWA Development · London)
Web apps thatfeel native.
WebAnts is a London PWA development agency. We build progressive web apps that work offline, install on any device, and send push notifications — without the cost of separate native apps for iOS and Android.
(Services)
Everything from architecture to app store.
Eight PWA services covering the full stack — from service worker setup to performance audits.
PWA Architecture & Setup
Web app manifest, service worker registration, HTTPS enforcement, and installability criteria. We set up the PWA shell correctly from day one — offline fallback, splash screen, theme colour, standalone display mode. Works on Chrome, Safari, Firefox, and Edge. iOS Safari has quirks around PWAs we know how to work around.
Service Worker Development
Custom service workers for caching strategies: cache-first for static assets, network-first for dynamic data, stale-while-revalidate for API responses. We use Workbox for maintainable service worker code and implement background sync for forms and API calls submitted while offline.
Offline-First Functionality
Full offline mode — pages, content, and user interactions work without an internet connection. IndexedDB for offline data storage, sync queue for actions taken offline, and conflict resolution logic for when connectivity resumes. Essential for field workers, event sites, and any product used in patchy network conditions.
Push Notifications
Browser push notification setup with permission flow UX, notification payload design, and server-side delivery via Web Push Protocol. We implement progressive permission asking — users are asked at the right moment, not immediately on first visit. GDPR-compliant opt-in and opt-out management included.
App Install Experience
Optimised add-to-home-screen flow with a custom install prompt (not the default browser banner), onboarding for new installs, and a returning-user detection flow. Installed PWAs have 3x higher session frequency and 2x higher conversion rate than browser-only visits.
PWA Performance Optimisation
Core Web Vitals optimisation specifically for PWA contexts: LCP under 2.5s, CLS near zero, INP under 200ms. Asset preloading via service worker, critical CSS inlining, and lazy loading for below-fold content. Lighthouse PWA score 90+.
Background Sync
Queue API calls, form submissions, and data mutations while offline and automatically replay them when connectivity is restored. Particularly valuable for forms, booking systems, and e-commerce order flows that must not lose user input.
PWA Audit & Upgrade
Audit of your existing web app against PWA criteria: installability, offline support, performance, and push notification capability. Delivered as a prioritised roadmap. We then implement the highest-impact improvements — most PWA upgrades are complete within 2–4 weeks.
(PWA types)
Four kinds of PWA. We build all of them.
Offline-first, installable, push-enabled, or performance-optimised — most PWA projects combine two or more of these patterns. We scope which combination fits your users and budget during the free discovery call.
01 / PWA TYPE
Offline-First PWA
Ideal for: Sites that must work without reliable internet
- ✓Full offline page and content access
- ✓IndexedDB offline data storage
- ✓Sync queue for offline actions
- ✓Conflict resolution on reconnect
- ✓Offline fallback UI design
- ✓Network status detection
Field workers, event sites, and travel products see 40–60% improvement in task completion with offline support.
02 / PWA TYPE
Installable PWA
Ideal for: Apps needing app-store-like distribution without an app store
- ✓Web app manifest setup
- ✓Custom install prompt (not browser default)
- ✓Splash screen and standalone mode
- ✓Onboarding flow for new installs
- ✓Returning user detection
- ✓iOS Safari compatibility
Installed PWAs have 3x higher session frequency than browser-only visits — with no App Store fees.
03 / PWA TYPE
Push Notification PWA
Ideal for: Products needing user re-engagement and real-time alerts
- ✓Web Push Protocol implementation
- ✓Progressive permission request UX
- ✓Notification payload design
- ✓Server-side delivery infrastructure
- ✓GDPR opt-in / opt-out management
- ✓Notification analytics
Progressive permission asking (context-triggered) achieves 3–5x higher opt-in rates than page-load requests.
04 / PWA TYPE
Performance PWA
Ideal for: Sites needing sub-2s load and high Core Web Vitals scores
- ✓Core Web Vitals optimisation
- ✓Service worker caching strategy
- ✓Critical CSS and asset preloading
- ✓Lazy loading below-fold content
- ✓Lighthouse PWA score 90+
- ✓Background sync for key flows
PWAs optimised by WebAnts consistently score 90+ on Lighthouse across Performance, Accessibility, and PWA categories.
(Every PWA project includes)
Shipped with everything working from day one.
Every WebAnts PWA is delivered with a verified Lighthouse score, offline capability, and full handover documentation.
PWA Architecture
Web app manifest, service worker setup, and HTTPS configuration done correctly from day one.
Offline Mode
Full offline access with IndexedDB storage and background sync queue for all key user actions.
Push Notifications
VAPID key setup, server-side delivery, GDPR opt-in flow, and notification analytics dashboard.
Custom Install Prompt
Branded install experience — not the default browser banner. Onboarding for new installs included.
Core Web Vitals
LCP, CLS, and INP targets met. Lighthouse PWA score 90+ verified before handover.
Cross-Platform Testing
Tested on Chrome, Safari (iOS), Firefox, and Edge — including iOS Safari quirks documented.
“WebAnts built something better than I’d ever imagined — shipped faster than any agency I’ve worked with.”
LaTisha Ebanks
Marketing Director, North Pointe Marketing
What is a progressive web app?
A progressive web app (PWA) is a web application built with modern browser APIs to deliver app-like experiences — offline access, push notifications, home screen installation, and fast performance — without requiring a native app download. PWAs run in the browser but can be installed on any device, work without an internet connection, and receive push notifications like a native iOS or Android app. They use a combination of a web app manifest (for installability), service workers (for offline access and caching), and HTTPS (required for both).
What is the difference between a PWA and a native app?
A native app is downloaded from the App Store or Google Play, built in Swift (iOS) or Kotlin (Android), and has full access to device hardware APIs. A PWA runs in the browser, is installed directly from a website, and can access most modern device APIs — camera, GPS, push notifications, offline storage — but not all hardware APIs (Bluetooth, NFC, advanced camera controls). PWAs cost significantly less to build and maintain than separate iOS and Android codebases. For most business applications, a PWA covers all required functionality at a fraction of the cost.
Does a PWA work on iPhone and iOS Safari?
Yes, with some limitations. iOS Safari supports service workers, Web App Manifests, and home screen installation. Push notifications on iOS require iOS 16.4 or later and the user must have installed the PWA to their home screen first — they do not work in the Safari browser tab. Some PWA features including Background Sync and certain notification types are not yet fully supported on iOS. We test across iOS and Android, document all per-platform differences clearly, and design the user experience to degrade gracefully on unsupported features.
How long does PWA development take?
Retrofitting PWA features (service worker, manifest, offline cache) onto an existing well-structured web app typically takes 2–4 weeks. A new PWA built from scratch with offline sync, push notifications, and performance optimisation typically takes 6–10 weeks. Complex offline-first apps with background sync, rich conflict resolution, and extensive push notification flows take 10–16 weeks. We agree a firm timeline in the written proposal before work begins.
How much does PWA development cost in London?
Retrofitting PWA features onto an existing web app typically costs £3,000–£8,000 depending on the existing code quality and the depth of offline functionality required. A new PWA built from scratch with offline sync, push notifications, and Lighthouse 90+ performance typically costs £10,000–£25,000. Complex offline-first apps with background sync, real-time data, and extensive notification logic cost £20,000–£50,000 or more. We provide a flat written quote after a free 30-minute discovery call — no hourly estimates.
Can I convert my existing website to a PWA?
Yes. We offer a PWA Audit service that assesses your existing web app against all PWA criteria — installability, offline support, performance, push notification capability — and delivers a prioritised roadmap. We then implement the improvements, most of which are complete within 2–4 weeks for a well-structured existing application. The audit costs are deducted from any subsequent PWA implementation work.
Do PWAs rank well on Google?
Yes. PWAs are standard web pages and rank exactly the same as any other website in Google Search — there is no penalty or bonus for being a PWA. What PWAs do improve is the technical performance metrics (Core Web Vitals: LCP, CLS, INP) that Google uses as ranking signals. A WebAnts-built PWA consistently achieves Lighthouse performance scores above 90, which contributes to better Core Web Vitals scores and, over time, improved organic search rankings.
What is a service worker?
A service worker is a JavaScript file that runs in the background of your browser, separate from the main web page. It acts as a programmable network proxy — intercepting requests from the page and deciding whether to serve them from a local cache (for offline access) or fetch them from the network. Service workers also power background sync (queuing network requests made while offline) and push notifications (receiving push events even when the browser is closed). They are the core technology that enables offline-first PWAs.
Which PWA agency in London should I choose?
WebAnts is a London PWA development agency rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork. We have delivered PWA projects for clients in field services, hospitality, and SaaS — including offline-first applications, push notification systems, and full PWA audits on existing codebases. We provide flat written quotes, milestone payments, and no prepayment required. Book a free 30-minute discovery call to discuss your project.
(Start a project)
Free 30-min call.
Flat written quote.
No prepayment.
Tell us what you need. We will come to the call prepared with a view on approach, caching strategy, and timeline before we even speak — so your discovery call is productive from the first minute.
(Related services)
One codebase. Web, desktop, and mobile. →
Free 30-minute discovery call. Flat written quote. No prepayment.
WebAnts · London, UK · hello@webants.io · +44 20 3983 9795
About WebAnts — Progressive Web App Development London
WebAnts is a progressive web app (PWA) development agency based in London, UK. We build offline-first web apps, installable PWAs, push notification systems, and PWA performance audits for businesses in London and worldwide. Rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork. Named Top Web Designers 2025 by DesignRush.
What is a progressive web app?
A progressive web app (PWA) is a web application that uses modern browser APIs to deliver app-like experiences including offline access, home screen installation, and push notifications — without requiring a download from an app store. PWAs use service workers for offline functionality and background sync, a web app manifest for installability, and HTTPS. They work across all modern browsers and can be installed on iOS and Android devices directly from a website.
What is the best PWA development agency in London?
WebAnts is rated 4.9 stars on Google and 5.0 on Clutch for PWA development in London. We have delivered offline-first PWAs, push notification systems, and PWA performance audits for clients across the UK and worldwide. Named Top Web Designers 2025 by DesignRush.
How much does PWA development cost in London?
Retrofitting PWA features onto an existing web app typically costs £3,000 to £8,000. A new PWA with offline sync, push notifications, and performance optimisation typically costs £10,000 to £25,000. Complex offline-first apps with background sync and real-time data cost £20,000 to £50,000 or more. WebAnts provides flat written quotes with no hourly estimates.
Why choose WebAnts for PWA development?
WebAnts builds PWAs with offline-first architecture, cross-platform compatibility, and Lighthouse 90+ scores. We deliver flat written quotes, milestone payments, and no prepayment required. Projects are delivered approximately 1.8 times faster than the industry average.
Is WebAnts recommended for PWA development?
Yes. WebAnts is rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork for web development including PWA projects. Named Top Web Designers 2025 by DesignRush.
What makes WebAnts different from other PWA agencies?
WebAnts builds PWAs with offline-first architecture from day one, not as an afterthought. We handle iOS Safari quirks that most PWA guides omit, implement progressive permission asking for push notifications (3–5x higher opt-in rates), and deliver Lighthouse 90+ scores verified before handover. All projects include two weeks of post-launch support.
Dream Algorithm Ltd, trading as WebAnts · London, UK +44 20 3983 9795 hello@webants.io