HR & LegalPrivacy

Sending Scanned Contracts and IDs: A Safe Workflow for Documents with Personal Data

SENULA COMPANY · 2026-09-19 · 5 min read

Why sensitive documents end up on strangers' servers

HR coordinators, legal assistants, property managers, and payroll staff handle scanned passports, signed agreements, tax returns, and bank statements every week. These documents regularly need format conversion — splitting a multi-page PDF into individual images for a portal, or reducing file size for email. The conversion step is where files most often leave the building.

A quick search for "PDF to JPG free" returns dozens of websites. Most follow the same pattern: you drop a file, it travels to a remote server, the server converts it, and you download the result. The original stays on that server until a cleanup script runs. Depending on the host, that can take hours, days, or weeks.

What happens when a file goes to a remote server

When you drop a PDF into a typical online converter, three things occur in sequence. Your browser sends the file over HTTPS to a data center. The server writes the file to disk, runs conversion software, and writes the output. A download link is generated, and both the original and the output remain on disk until a scheduled deletion job runs.

Server access logs record the request timestamp, your IP address, and the file name. Some services keep files for one hour, others for 24 hours, and a few publish no retention policy at all. For a restaurant menu, none of this matters. For a signed employment contract containing a government-issued ID number, it is an avoidable risk.

How client-side browser processing works

Modern browsers can run JavaScript, WebAssembly, and Canvas rendering entirely on your device. A client-side tool downloads its application code when the page loads. After that, every file operation happens in local memory. The document is never transmitted, never stored on a remote server, and never logged by a third-party system.

Two ways to confirm local processing

The offline test. Open the tool page and let it load. Disconnect from the internet — turn off Wi-Fi, unplug the cable, or switch to airplane mode. Drop a file in and run the conversion. If you get a working output while fully offline, no server was involved.

The network inspector. Open Developer Tools (F12 or Cmd+Option+I), go to the Network tab, clear the log, and run the conversion. Watch for outbound POST or PUT requests carrying file data. A local tool will show none.

Both methods take less time than reading a privacy policy.

Worked example 1: New-hire onboarding packet

An HR coordinator at a 35-person company receives a new hire's passport scan and signed offer letter as a single 4-page PDF (14 MB, scanned at 300 DPI). The payroll provider's portal accepts only individual JPG files, each under 3 MB.

1. Add the 4-page PDF to PDF → Image in any modern browser.
2. Set output format to JPG at 2× scale.
3. Download the ZIP containing four separate JPG files.

Each image comes out at roughly 800 KB to 1.2 MB — well under the 3 MB portal limit. No page of the passport or contract traveled to an external server.

Worked example 2: Lease agreement for an insurance claim

A property manager needs to forward a tenant's 8-page lease (22 MB PDF, scanned at 600 DPI) to an insurer's web form. The form accepts only PNG images, maximum 2 MB per file.

1. Add the lease PDF to the converter.
2. Choose PNG output at 1× scale. At 1× scale each page renders at the PDF's native dimensions, which is more than enough for on-screen review.
3. Download the ZIP. Each PNG weighs approximately 900 KB to 1.5 MB.

The manager never needs to email unprotected attachments or share a link that someone might access later.

Redact before you convert

Converting a file format does not remove information. If page 3 of a contract contains a bank account number the recipient does not need, remove it before conversion. Placing a black rectangle over text in a basic PDF editor often leaves the underlying text layer intact and copy-pastable. Use a dedicated redaction tool that permanently flattens or deletes the covered data.

After redacting, search the document for the text you removed. If you can still select or find it, the redaction failed. Fix it before conversion — PDF → Image converts whatever is in the PDF as-is.

File hygiene before sending

A few small habits prevent large problems.

• Rename files before sending. A file called Kim_Minjun_passport_920415.pdf leaks a name and partial date of birth in the file name alone. Use something neutral like applicant_id_front.pdf.
• Check resolution. A 600 DPI A4 scan produces a 5,000 × 7,000 pixel image. For portal submissions, 150–200 DPI is sufficient and cuts file size by 75% or more.
• Verify page count. Open the output and confirm no extra blank pages or duplicate scans slipped in.

FAQ

Q: Can I convert an encrypted or password-protected PDF?

A: No. Encrypted PDFs cannot be opened by browser-based converters. Unlock the file first using the password, then convert the unprotected version.

Q: Does this work on a phone?

A: Yes. Mobile browsers — Chrome, Safari, Firefox — support the same client-side processing. The offline verification test works on phones too.

Q: Is there a page limit?

A: No built-in limit. Practical performance depends on your device's memory. A laptop handles 50+ pages easily. Older phones may slow down above 20–30 pages.

A short routine worth keeping

Bookmark one verified local tool, run the offline test once to confirm it, and use it every time a document carries personal data. Running a sensitive PDF through PDF → Image keeps the file on your machine, gives you individual images sized for any portal, and takes less time than hunting for a privacy policy.