On-device vs server-side PDF processing: what changes for your app
Where a PDF is edited decides who can see it, whether your app works offline and what you have to run. How the two approaches compare, and what PDF-SDK does.
Every app that edits PDFs makes a choice early, often without noticing it: does the document travel to a server to be changed, or is it changed where it already is — on the user's phone, tablet or browser tab?
Two ways to edit a PDF in an app
Server-side processing sends the document to a server, edits it there, and sends back the result. The app is a thin client; the heavy lifting, and the document, live on a machine you run or trust.
On-device processing puts the editor inside the app. The document is opened, changed and saved in the app's own memory, and nothing about it has to leave the device.
What changes for your users
| On-device | Server-side | |
|---|---|---|
| Where the document goes | Nowhere — it stays on the device | To a server, and back |
| Without a connection | Works | Stops |
| Each change | Happens on the device | A round trip to the server |
| Who can see the document | Your app, on the user's device | Your app and the server it passes through |
What changes for you
With a server, there is a service to run: capacity, uptime, storage, and a copy of every document your users edit, with the security and privacy duties that come with holding it.
On the device, there is no document server to run or secure. What you take on instead is the editor itself — its size in your app and the platforms it has to support — which is what a PDF SDK is for.
Privacy and compliance
When documents never leave the device, there is less to protect in transit and nothing to keep on a server. That does not make an app compliant on its own — compliance belongs to your app and your processes — but it removes a whole category of data from your systems.
How PDF-SDK does it
PDF-SDK is on-device on every platform: the same engine runs inside your iOS, Android, Flutter or React Native app, and inside the browser tab on the web.
- Documents never reach us. There is no document server, ours or yours.
- Standard license keys are checked on the device, with no network call at all.
- Online licenses confirm with our license server from time to time — sending the license key, the app's identity and the SDK version, never a document — and work offline in between.
- Signing keys stay in the device's keystore, or in your own HSM or signing service.
The details, including exactly what the license server keeps: Security. To see it for yourself, open the live demo with your browser's network panel and edit a document.
Questions
Yes. With PDF-SDK the document is opened, edited, signed and saved on the device. A standard license key is checked on the device too; an online license works offline between confirmations, 30 days by default.
It runs on the user's own hardware, so it depends on the device and the document. There is no upload or download step, which a server-side approach needs for every change.
Yes. PDF-SDK hands your app the edited PDF; where it is stored is your choice. The SDK itself never uploads it.
Try it in your app
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