What works without internet.
Load Toolzum once, and local tools keep running with no connection. Network tools do not — here is the exact line.
Works fully offline
After first load — no connection needed.
- Calculators (all 66)
Pure local math in the CalculatorShell — no fetch call anywhere in the compute path.
- Local converters & editors
Image, PDF, audio and video tools process files in-browser via WebAssembly and JavaScript.
- Text, encoder & generator tools
Case converters, encoders, password and UUID generators never touch the network.
- PDF worker pipeline
The pdf.js worker ships same-origin and is precached; each PDF tool's own page and bundle are cached the first time you open that tool, so it works offline from then on.
Needs internet
Each one makes a network request — verified in component code.
- AI credit tools
Every answer calls /api/ai/generate, /api/ai/generate-image, /api/ai/transcribe or /api/ai/describe-image — no connection, no credits spent, no answer.
- RDAP / WHOIS & domain availability
WhoisLookup and DomainAvailabilityChecker fetch /api/rdap-lookup plus DNS-over-HTTPS — inherently live lookups.
- URL shortener
UrlShortener posts each URL to /api/url-shorten, which calls third-party shortening providers server-side.
- URL status checker & screenshot
They post to /api/url-status-check and /api/fetch-page to probe live sites on your behalf.
- Currency converter live rates
CurrencyConverter fetches /api/currency-rates (hourly-cached upstream feed) — saved rates show, fresh rates need internet.
- Translation tools
TranslatePdf calls the MyMemory translation API per chunk — translation is a network operation.
- Temporary email inbox
TempEmailInbox fetches temp addresses and messages from a worker API — mail cannot arrive offline.
- Dictionary / pronunciation lookup
PronunciationTool queries dictionaryapi.dev for definitions — cached words show, new words need internet.
Install the app
Android / Chrome
- Open toolzum.com in Chrome.
- Tap the three-dot menu.
- Choose “Install app” (or “Add to Home screen”) and confirm.
iPhone / Safari
- Open toolzum.com in Safari.
- Tap Share.
- Choose “Add to Home Screen” and confirm.
What gets precached
The service worker (registered automatically in production only) precaches:
- The app shell: the home page plus the JS and CSS it loads
- Offline fallback page (/offline, bound to navigation fallback)
- pdf.worker.min.mjs — the same-origin PDF worker
- manifest.json, icons, robots.txt and sitemap.xml
Everything else arrives on use: every tool page and its bundles are cached the first time you open that tool, so your regulars keep working offline while the rest of the 1,000+ pages are not downloaded on your first visit. The tool directory (/tools/) is cached the same way.
Offline questions, answered.
Do I need to install anything to use Toolzum offline?
No manual step is required. On your first visit in production the service worker registers automatically and precaches the app shell, so repeat visits load even with flaky internet. Installing the app just adds a home-screen icon and a standalone window.
Why do some tools fail without internet?
Any tool that calls fetch needs the network: AI tools (credit APIs), RDAP/whois, the shortener, live currency rates, translation, temp-mail and dictionary lookups. Pure-computation tools — calculators, converters, editors — keep working because they never make a request.
Is Toolzum 100% offline?
No — and we will not claim that. Local tools work fully offline after first load, but AI, lookup, shortening, live-rate, translation and inbox tools fundamentally need a connection. This page lists exactly which is which.
Does offline mode change my privacy?
Offline strengthens it: with no requests leaving your device, even analytics and quota pings cannot fire. Files were already processed locally, so offline simply removes the last reason anything could leave the browser.