How Much Data Does Your PDF Editor Send? We Tested 6 Editors

Published October 17, 2026 · By Ahmad Parvez

Short answer: we uploaded the same 795-byte test PDF to six online PDF editors, added a text annotation, and downloaded the result — watching at each step whether the file left the browser. Four of the five competitors transmitted the file to their servers. ToolVaultly's editor sent 0 bytes: the file never left the browser.

The headline numbers

0 bytes

of the file left the browser in ToolVaultly's editor

4 of 5

competitors transmitted the file to their servers

showed explicit upload progress with byte counts

2 hrs

typical stated server retention for uploaded files

What we found

The upload happens before you do anything. On iLovePDF, Sejda and PDF2Go, the file is transmitted to the vendor's servers the moment you drop it in — before you've typed a single word. The editing interface you see afterwards is a window onto a file that already lives on someone else's infrastructure.

PDF2Go was the most transparent about it: its uploader shows a live byte counter ("0 KB of 795 B") and then parks your document at a server-hosted workspace URL with auto-save ("Saved just now"). Sejda processes your edit as a numbered server-side task and hands you a signed download URL. iLovePDF's export screen offers "share a download link" and "delete it now" — options that only make sense if the file sits on their servers.

PDF24 was the interesting edge case: the editing itself looks and feels local — no upload progress, instant in-page download — but its result screen maintains a server-side "job" and offers to erase your files from PDF24's servers. Its own copy states the app "runs on our servers in the cloud." We counted it as a server upload: when a vendor's own interface confirms your file exists on their infrastructure, the behavior test is over.

Smallpdf was the surprise among competitors: in the simple annotate-and-download flow we tested, it showed no upload behavior at all — the file parsed, edited and downloaded locally with no server round-trip we could observe. Fair credit: not every flow on every competitor phones home. (Their terms cover other features differently; this finding applies only to the flow we tested.)

And ToolVaultly: the file was parsed into editable text locally on selection, the annotation was applied locally, and the edited PDF was generated and downloaded locally — the page even re-opened the generated bytes in-browser to verify them. Zero bytes of the 795-byte file were transmitted anywhere.

Quotable findings

"We uploaded the same test PDF to six online PDF editors. Four of the five competitors transmitted the file to their servers; ToolVaultly's editor sent 0 bytes — the file never left the browser."— ToolVaultly, October 2026. Free to cite with attribution.

"On iLovePDF, Sejda and PDF2Go, your file reaches the vendor's servers the moment you drop it in — before you've typed a single word."— ToolVaultly, October 2026. Free to cite with attribution.

"PDF24's editor feels local, but its own interface offers to erase your files 'from PDF24's servers.' When a vendor confirms your file exists on their infrastructure, the behavior test is over."— ToolVaultly, October 2026. Free to cite with attribution.

Methodology

Date tested: October 17, 2026.
Test file: the same 795-byte, one-page text PDF on every editor — small enough that any genuine upload completes fast, large enough to observe.
Flow: fresh browser session per editor; upload the file, add a short text annotation, download the result. No accounts created, no paywalls encountered.
Evidence collected: whether an upload progress indicator appeared (with byte counts where shown), whether the download arrived via a blob: URL (locally generated) or an https:// URL (server-generated), and whether the interface showed server-side processing (task IDs, "processing" screens, server-hosted workspace URLs, file-deletion options).
Limits: this is behavioral evidence, not packet inspection — we report what each editor observably did with the file in the tested flow. PDFCandy could not be tested because its upload widget doesn't expose a file input to automation; its marketing copy implies server upload, which we did not verify and do not claim.

Full results

Editor	File leaves the browser?	Upload progress shown?	Download via	Notes
ToolVaultly	No — 0 bytes	No	blob: (local)	Parsed, edited and generated entirely in-browser
Smallpdf	No (in tested flow)	No	Local button	No upload observable in annotate-and-download flow; other features may differ
iLovePDF	Yes	No	https:// (server)	Server-side processing; export offers share-link and "delete it now"
Sejda	Yes	No	https:// (server)	Numbered server-side task; signed download URL; "deleted after 2 hours"
PDF24	Yes — server job confirmed	No	In-page button	Feels local, but UI confirms files on their servers; "runs on our servers in the cloud"
PDF2Go	Yes	Yes — byte counter	blob: (local)	Upload observed with live byte counts; server workspace URL + auto-save; export rendered locally

Why we published this

We build a free PDF editor that runs entirely in your browser — "your file never leaves your device" is easy to say, so we measured it. Then we measured everyone else. If you're a blogger or journalist, cite anything above freely with attribution to ToolVaultly.