The verdict in three sentences
A classic 4 MB site in a 3G area is unusable the moment the signal bar drops to one. An offline-first PWA caches already-seen pages and images and places forms submitted offline into a queue synced when the network returns. Estimated result: target weight under 1 MB, bounce down about 50 % in weak-signal areas, and a site that opens even with no connection.
Strong network vs weak network: the real experience
| Criterion | Classic site 3G/weak area | Offline-first PWA |
|---|---|---|
| First-visit weight | 3-5 MB | 0.7-1 MB |
| Second visit (cache) | Reloads everything | Opens in < 1 s, offline |
| Form with no network | Fails, data lost | Queued, sent on return |
| Bounce rate weak area | 60-75 % | 30-40 % |
| Data per visit | 3-5 MB | 0.1-1 MB |
| Install to home screen | No | Yes (icon, full screen) |
The key difference is not speed on strong networks, it is survival on weak networks: the PWA keeps working where the classic site shows a blank page.
What makes a PWA offline-first
Three technical building blocks do the work. The service worker intercepts requests and serves the cache when the network is missing. The app cache stores already-viewed pages, fonts and images. Background Sync keeps forms (quotes, contact, order) queued and sends them as soon as the network returns, without the user starting over.
| Item | Indicative 2026 cost | Gain |
|---|---|---|
| Convert existing site to PWA | 300,000-700,000 FCFA | Offline + installable |
| Weight optimization under 1 MB | Included / 150,000 FCFA | -50 to -80 % data |
| Form queue (Background Sync) | 150,000-300,000 FCFA | Zero lead lost offline |
| WebP/AVIF image cache | Included | 2-3x faster loading |
Mini case study
Ibrahima runs an agricultural cooperative 80 km from Thies, in an area with intermittent connection. His old 4.2 MB site showed a blank page every other day for his members. After conversion to an offline-first PWA at 480,000 FCFA, the site weighs 850 KB, opens offline and queues order forms. Bounce drops from 68 % to 34 %, and on 200 monthly visitors in the weak area, about 68 extra leads per month come through instead of being lost.
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
FAQ
Does a PWA replace a native mobile app?
For most SMEs, yes: the PWA installs to the home screen, works offline and sends notifications, without store fees. A native app is only justified for advanced hardware needs.
How much data does a PWA really save?
After the first visit, a well-optimized PWA uses 0.1 to 1 MB per session versus 3 to 5 MB for a classic site, up to 80 % less data, a strong argument in a market where data is paid per megabyte.
Do forms sent offline really arrive?
Yes: Background Sync stores the submission locally and sends it automatically as soon as the network returns, even if the user closed the tab. No lead is lost.
What weight should I target for a good 3G experience?
Aim for under 1 MB on first visit and under 1 second to open on subsequent visits thanks to the cache. That is the threshold where the site stays usable even on a single signal bar.
Let's talk about your project. We convert your site into an offline-first PWA under 1 MB, with a form queue so no lead is lost in weak-signal areas. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
