What a Browser PDF App Actually Stores on Your Device

‘Works offline’ sounds like a pure convenience feature until you turn it around: for a page to open with no connection, something must already be sitting on your device. That is a reasonable thing to be suspicious about. Anyone who has just fed a browser tab a tax return, a signed contract, or a medical form is entitled to ask precisely what was written to disk, where, and how to get rid of it.

This post is that inventory for Novus PDF Studio — not a reassurance, a list. Every item below corresponds to something the app actually writes, and the section on what is deliberately absent matters just as much. The short version: the application and a handful of preferences are stored automatically. Document bytes enter IndexedDB only after an explicit action — either a short-lived homepage handoff or Save on this device in the editor — and never as autosave.

Browsers give a site four broadly different places to leave something behind, and conflating them is where most anxiety comes from. Cache storage holds copies of files fetched over the network. Local storage holds small named strings the page wrote deliberately. Cookies are short values sent back with each request. IndexedDB can hold larger structured records and document bytes. Novus uses each for a distinct purpose, with document storage behind a user action.

The service worker keeps a copy of the site’s own build output — scripts, stylesheets, icons, fonts, and the HTML for the home page, the editor, the tools hub, and the offline notice. Pages you visit afterwards add their own code to a runtime cache so a second visit is instant. That is the entire content of the cache: files the server sent to your browser.

Your PDF cannot enter the service-worker cache, and not because a rule merely promises it. That cache stores network responses, while a file picker hands the page an in-memory File object rather than a URL to fetch. There is no document request for the cache to intercept. If you explicitly save an editor session, the separate IndexedDB store receives a local copy; the document still never becomes a network response or an upload.

• novus-pdf-cookie-consent — whether you accepted or declined optional cookies.
• novus-pdf-cookie-preferences — the detailed version of that choice, including when it was made.
• novus-theme — light or dark. Read before the first paint so the page does not flash the wrong theme at you.
• novus-pdf-pwa-install-dismissed — set when you close the install prompt, so it does not reappear.
• novus-pdf-blog-feedback — your per-article helpful/not-helpful answers, only after you press one of those buttons. The answers stay in this browser and are not sent to us.

That is the complete public interface list. None of these values holds an account, filename or document content, and Novus does not transmit them to its own server. A developer-only scan-debug switch may appear if someone deliberately creates novus-scan-debug; the application does not write that key itself.

novus-ad-region records whether prior consent is required where you are connecting from — one of two values, decided at the edge, so the consent banner behaves correctly without anyone storing your location. novus-gpc records that your browser sent a Global Privacy Control signal, so that preference survives the page load. Neither holds an IP address or a precise location. The cookie policy is the authoritative version of this and includes a reset control.

The editor's Save on this device control writes the PDF bytes, filename, page count and current editor layers to the novus-pdf-local-sessions IndexedDB database. The control checks the browser's estimated quota before an atomic write, reports the retained size, and offers per-session deletion plus Delete All. A saved session remains until you delete it, clear site data, or the browser evicts non-persistent storage. A failed save leaves the live editor unchanged.

The homepage intake uses the same database differently: after you choose a PDF and explicitly continue to the editor, it creates one handoff record. The editor reads and deletes that record, and rejects it after 30 minutes. This avoids placing bytes in a URL or a server request; it is not a recent-session save.

There is still no autosave, background draft or server-side recovery file. A password used to open or protect a PDF is never written to IndexedDB, local storage, cookies or the service-worker cache. Document bytes and editor layers persist only when you take the named save or handoff action; otherwise the working copy exists only in the tab until export or close.

1. 1

   Open your browser’s developer tools

   Use the Application (Chrome, Edge) or Storage (Firefox, Safari) panel while Novus is open.

2. 2

   Read the cache entries

   Expand cache storage and scan the list. Everything there is a build asset served from this site — scripts, styles, icons, and page HTML.

3. 3

   Read the local storage entries

   Compare what you see against the names above. The article-feedback key appears only after you answer an article.

4. 4

   Inspect IndexedDB

   Expand novus-pdf-local-sessions. It is empty until you use homepage Continue or Save on this device. Save a test session, verify its filename and size, then delete it with the editor controls.

5. 5

   Watch the network while you edit

   Open a PDF, fill a field, and export with the network panel recording. No request carries your file.

6. 6

   Do the airplane-mode test

   Disconnect and repeat the export. It completes, which is only possible if the work was local all along.

The reset control on the cookie policy page removes the two consent entries. The editor's saved-session controls delete one session or every saved session without touching the live editor. Clearing this site's data in your browser removes everything — cached application files, local-storage preferences and feedback, IndexedDB sessions and handoffs, and first-party cookies. If you installed it as an app, uninstalling removes the launcher entry; clearing site data is still the step that empties browser storage.

None of this needs to be taken on trust, which is the point. Storage inspection takes a minute, the network panel is unambiguous, and airplane mode is a decisive test that no marketing copy can fake. If you are weighing Novus against another browser-based tool, run the same three checks on both — see what browser-local processing actually changes for the wider comparison.