WebAssembly and JavaScript process merge, compress, redact, and GST invoices on this device. What never leaves, and what still uses the network.
Most “online PDF tools” are upload forms. The browser sends the file to a server, a worker converts it, and a download link comes back. That is simple to build. It also means a CV, a contract, or an Aadhaar scan is copied onto a machine you do not control for the length of the job — and sometimes longer, if the host logs or caches it.
PDF on Browser does the work in the tab. When you open Merge, Compress, Redact, or GST Invoice, this page loads static JavaScript and WebAssembly (pdf-lib for structure, PDF.js for rendering, and similar libraries for Office, OCR, and zip). Those libraries then read the file you drop. The bytes stay in memory on this device. We do not POST the document to pdfonbrowser.com for conversion.
What never leaves the device: document bytes, filenames, page text, form field values, GSTIN line items you type, and redaction boxes you draw. There is no account and no KYC pipeline, so there is nothing to attach those values to.
What still uses the network, on purpose: the first load of the static app (JS, CSS, WASM, the PDF.js worker), optional Google Analytics 4 if a measurement id was configured at build time (no document text or filenames), and Razorpay checkout only if you choose to tip after a download. Skip never creates a charge. A tip happens after the file is already on disk — the PDF is not held hostage.
The practical test is that the file is never posted for conversion. If a site only works while the upload spinner runs, it is not an in-tab tool. Processing here uses the libraries already loaded in this tab; the document bytes stay on this device.
This is not magic privacy. The browser itself, extensions, and your own disk can still see the file. We are making a narrower claim: pdfonbrowser.com does not receive the document for processing. Use Compress, Merge, Redact, or GST Invoice when the file is one you would not happily email to a stranger.
Document bytes, filenames, page text, and form values are not sent to pdfonbrowser.com for merge, split, compress, convert, redact, OCR, or GST invoice generation.
The static app files when the page loads, optional analytics if a measurement id is configured, and Razorpay only if you tip after a download. Skip never creates a charge.
No. Compress, merge, and redact run in this tab after the page has loaded.