Most browser extensions make network requests — fetching data, syncing state, connecting to APIs. Some work entirely offline.
Here are Firefox extensions that run completely without a network connection, and extensions that need one but make minimal requests.
Fully offline: no network requests
NightOwl — calculates sunset and sunrise mathematically from your location coordinates. No API request needed. Works in airplane mode.
Tab Manager and Session Saver — saves tab URLs to local storage. No network request on save or restore.
Daily Planner and To-Do List — tasks stored locally. No sync, no server.
Habit Tracker — habit grid stored locally. Works without connection.
AI Writing Assistant — grammar model runs in the browser. No API calls for grammar checking. (Currency conversion, if used, requires a connection.)
Quick Calculator — arithmetic and unit conversion done locally. Currency conversion requires a connection; all other calculations are offline.
Speed Dial Hub — site shortcuts stored locally. The extension itself loads offline (the sites you navigate to require a connection).
Voice Notes — records audio locally. The recording itself requires no network.
Requires network: minimal requests
Weather and Clock Dashboard — one weather API request per update interval. Clock works offline; weather requires connection.
News Widget Dashboard — fetches RSS feeds periodically. Headlines cached locally between refreshes.
Stock Market Dashboard — fetches market data. Last prices cached between refreshes.
Why offline capability matters
For users on trains, planes, or unreliable connections, knowing which tools work offline is useful. For users on corporate networks with outbound filtering, local-processing tools reduce the number of approved-destination exceptions needed.
All 11 are part of a series of Firefox extensions I built — see the full series.
Top comments (0)