PDF compression guides
How to Check Whether an Online PDF Tool Uploads Your File
A practical browser-based check for a file-handling claim, with clear limits on what the result means.
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To check whether an online PDF tool uploads a file, use a non-sensitive test document, open the browser Network panel before choosing the file, and inspect requests made during processing. Look for requests whose payload contains the document or whose transfer size tracks the file. One observation is useful evidence for that workflow, not a complete audit of every browser extension, device service, or future release.
What this check can show
A browser Network panel shows requests initiated by the page in the current session [1]. It can help distinguish page resources from a request that carries the selected test document. It does not inspect unrelated browser extensions, operating-system traffic, or a provider's infrastructure beyond the requests visible in that session.1
| Situation | Next step |
|---|---|
| The original file is the record or may be needed again. | Keep it unchanged and work only on a copy. |
| A recipient relies on a specific feature or validation result. | Run the applicable check before sharing the downloaded copy. |
| The document is signed, archival, encrypted, damaged, or policy-controlled. | Stop and use the workflow required by the owner or recipient. |
Check a PDF workflow with a non-sensitive file
- Use a throwaway or non-sensitive PDF. Do not use a confidential document as a test fixture.
- Open the browser Network panel and clear previous requests before selecting the file.
- Choose the file, run the workflow, and inspect new requests for request method, destination, transfer size, and any visible file payload.
- Record the browser, date, page URL, and observed request summary so the result is reproducible.
- Download the result and inspect it separately before sharing it.
What PDFStay states for supported ordinary PDF tasks
PDFStay states that supported ordinary PDF tasks run in the current browser session and that ordinary PDF content is not sent to PDFStay servers [2] [3]. The site still loads web resources, and this statement is not a claim that every network request from a device is absent.2, 3
FAQ
Can a Network-panel check prove that no data ever leaves my device?
No. It records the requests visible for one workflow in one browser session. Use it as concrete evidence for that test, not as a complete security audit.
Should I test a confidential PDF?
No. Use a non-sensitive fixture or a copy created for testing.
What should I record?
Record the page URL, browser and version, date, test-file size, the workflow used, and a concise request summary.
Sources
- Chrome for Developers — Inspect network activityofficial technical documentationSource reviewed:
- PDFStay Privacy PolicyPDFStay first-party methodologySource reviewed:
- PDFStay — Compress PDF workflowPDFStay first-party methodologySource reviewed: