What the service worker actually does for you
A service worker is a script that sits between your app and the network. Done right, it caches the app shell and key assets so return visits load almost instantly, and it lets the app keep working when the connection drops. This is the engine behind the 'fast and reliable' feel people associate with good PWAs.
We match the caching strategy to each type of content: cache-first for things that rarely change like fonts and icons, network-first for data that must be fresh, and stale-while-revalidate where showing something instantly then updating quietly is the best experience. Getting this mapping right is most of the job.
- App-shell caching for near-instant repeat loads
- Offline fallback pages and cached data where it makes sense
- Per-content strategies: cache-first, network-first, stale-while-revalidate
- Precaching of critical assets at install time
- Background sync so actions taken offline complete later
- Built with proven tooling (such as Worksbox) rather than fragile hand-rolled logic
Getting updates right — the part most setups get wrong
The classic caching bug is users seeing an old version of your app after you've shipped a fix, because the service worker is serving stale files. We set up proper versioning and update handling so new deployments roll out cleanly — often with a subtle 'update available' prompt rather than a silent stale cache.
We also make sure caching never hides critical fresh data — payments, live inventory, account status — and that clearing or updating the cache is predictable. This is exactly the layer where cutting corners causes 'why isn't my change showing up' problems weeks later.
- Versioned caches so new releases replace old ones cleanly
- Update prompts so users aren't stuck on a stale build
- Fresh-data guarantees for payments, inventory, and account state
- Safe cache invalidation and cleanup of old versions
- Testing across offline, flaky, and online conditions
- Clear documentation of what's cached and why
More on progressive web apps
Frequently asked questions
Will caching make users see outdated content?
Only if it's set up carelessly — and that's the most common PWA complaint. Done properly, with versioned caches and update handling, users get instant loads for stable assets and fresh data for anything that changes. Preventing the stale-content problem is a core part of how we build the caching layer.
How much can actually work offline?
It depends on the app. Read-heavy content and previously loaded data can work fully offline; actions that need the server (like a live payment) can queue and complete when the connection returns. We scope exactly which features work offline versus require a connection so expectations are clear.
Can you add or fix a service worker on an existing PWA?
Yes. If your current app is slow on repeat visits, breaks offline, or serves stale content, we can audit the existing service worker and rework the caching strategy without rebuilding the whole app.