How can I tell if a web tool is processing client-side?

Look for an explicit statement from the provider, or check your browser's network activity — a client-side tool shouldn't show your input data being sent in any network request while you use it.

Is client-side processing always more private?

It removes the step of your data being transmitted to and stored on someone else's server, which is a meaningful privacy improvement for most sensitive use cases — though the browser and device you're using still see the data, same as any local application.

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Privacy

Client-side vs. server-side processing

Reviewed by the Tabreon team · Last updated: September 2026

Quick answer

Client-side processing happens entirely on your own device, inside your browser — your data never has to travel anywhere. Server-side processing sends your data to a remote server to be processed there.

Why this matters

Knowing which model a tool uses tells you whether your data ever leaves your device — a meaningful distinction for anything sensitive, from a private document to a password.

Definition

"Client" refers to your device — the browser running on your computer or phone. "Server" refers to a remote computer, operated by the service you're using, somewhere on the internet. Client-side processing means the computation (formatting text, resizing an image, editing a PDF) happens using your device's own processor and memory. Server-side processing means your input is transmitted over the network to the server, processed there, and the result sent back.

How it works

For a client-side tool, JavaScript running in your browser tab reads your input directly (via the File API, a text box, etc.), performs the operation using browser-native capabilities, and shows or downloads the result — no network request carrying your data occurs. For a server-side tool, your input is packaged into a network request, sent to the server, processed by code running there, and the response sent back over the network.