A PDF editor that works without a connection
The editor is static files plus a WebAssembly engine. Once the page has loaded, nothing else is required from the network, including while you edit and export.
What offline means here
PdfCanvas does not stream your document to a server, so the editing session has no network dependency. If you disconnect after the app has loaded, rendering, text editing, signatures, page management and export keep working.
The first visit still downloads the app and the PDF engine, as any website does. On a slow connection the first load is the only part that feels like a normal web app.
When this matters
- You work on a laptop with unreliable Wi-Fi, on a train, or on a locked-down corporate network.
- The document is covered by an NDA and cannot be sent to a third-party service.
- You are handling personal data and want to avoid creating a copy on someone else's server.
- You need to sign or annotate a file during a call, without waiting for an upload.
How to confirm it is really local
Open the editor, load a PDF, then switch the browser dev tools to the Network tab and set it to Offline. Continue editing and export. If the file were being processed remotely, the export would fail.
The page itself is still a website. Clear the cache and a fresh load needs a connection again; only the document is guaranteed to stay on your device.
Self-hosted for a permanent local copy
If you want the editor to live entirely inside your network, build the site and host the static output on your own server. There is no backend to install, no database, and no outbound call in the editor.
Frequently asked questions
+Can I install it as an app?
The site ships a web app manifest, so it can be added to the home screen. Full offline caching of the app shell is not enabled yet, so a cold start still needs a connection.
+Does the PDF engine download from a CDN?
No. The worker and the PDFium WebAssembly file are served as static assets from the same origin as the site.
+Can I edit on a plane?
Yes, as long as the editor page finished loading before you lost the connection.
+Is there a desktop version?
No. The browser build is the product; the same code can run inside an Electron or Tauri wrapper you control.