Logo
Get started
Apdf tutorials October 2026 4 min read

How to Add Per-Recipient Watermarks, Then Track Every Read

Confidential documents leak two ways: forwarded quietly, or screenshotted loudly. Watermarks handle the second — a name in the footer makes every screenshot traceable. But a watermark can't tell you the document is circulating before the leak, and tracking alone can't deter what it only observes.

So do both, in one pipeline: every recipient gets a copy stamped with their own name, behind their own tracked link. Deterrence on the page, visibility on the wire.

What you'll build
One script, one CSV, and each name comes back as a personal, watermarked, tracked copy: Miriam Wolfe → her copy says “licensed to Miriam Wolfe” — and reports every read she makes
Everything in this tutorial works on the free plan
1

Understand the four-call chain

The whole pipeline is API results feeding API inputs — no downloads in between: 

POST /api/pdf/file/create      HTML in            → personal stamp page (async job)
POST /api/pdf/page/overlay     base + stamp in    → watermarked copy URL
POST /api/docs                 that URL in        → tracked document
POST /api/docs/{id}/links      name + email in    → the URL you send

The elegance is in step three: processing results are hosted URLs, and the documents endpoint ingests by URL — so the watermarked copy flows straight into tracking without ever touching your disk.

2

Run the pipeline over your list

#!/usr/bin/env bash
# Per-recipient watermark + tracked link, one pipeline per name.
API="https://apdf.io/api"
H=(-H "Authorization: Bearer $API_TOKEN" -H "Accept: application/json")

while IFS=, read -r NAME EMAIL; do
  # 1. generate the personal stamp page (async job)
  STAMP="<html><body style=\"margin:0;width:100%;height:100vh;position:relative;overflow:hidden;\">
    <div style=\"position:absolute;top:50%;left:50%;transform:translate(-50%,-50%) rotate(-35deg);font-family:Arial;font-size:64px;font-weight:bold;color:rgba(200,30,30,0.18);white-space:nowrap;letter-spacing:6px;\">CONFIDENTIAL</div>
    <div style=\"position:absolute;bottom:24px;left:0;right:0;text-align:center;font-family:Arial;font-size:11px;color:rgba(120,120,120,0.55);\">Copy licensed to $NAME · not for distribution</div>
  </body></html>"
  JOB=$(curl -s "${H[@]}" -X POST "$API/pdf/file/create" \
    --data-urlencode "html=$STAMP" -d "format=a4" \
    -d "margin_top=0" -d "margin_bottom=0" -d "margin_left=0" -d "margin_right=0" | jq -r .job_id)
  sleep 1
  until STAMP=$(curl -s "${H[@]}" -X POST "$API/job/status/check" -d "id=$JOB" | jq -re '.result.file') 2>/dev/null; do sleep 2; done

  # 2. overlay it onto every page of the report
  sleep 1
  STAMPED=$(curl -s "${H[@]}" -X POST "$API/pdf/page/overlay" \
    --data-urlencode "file=$BASE_PDF" --data-urlencode "overlay=$STAMP" -d "repeat=1" | jq -r .file)

  # 3. upload the personal copy as a tracked document and mint the link
  sleep 1
  DOC=$(curl -s "${H[@]}" -X POST "$API/docs" \
    --data-urlencode "file=$STAMPED" --data-urlencode "name=Board Report — $NAME" \
    -d "is_public=0" | jq -r .data.doc_id)
  sleep 1
  URL=$(curl -s "${H[@]}" -X POST "$API/docs/$DOC/links" \
    --data-urlencode "name=$NAME" --data-urlencode "email=$EMAIL" | jq -r .data.url)

  echo "$NAME → $URL"
  sleep 1
done < <(tail -n +2 recipients.csv)
$ BASE_PDF=https://your-site.example/board-report.pdf API_TOKEN=... ./stamp-and-track.sh
Miriam Wolfe → https://docs.apdf.io/studio/e6a74-8bc24-77c31?v=JbWCV5aQ
Viktor Chen → https://docs.apdf.io/studio/a42a6-f7ca0-9bf31?v=EPNDFGmS

We pulled Miriam's finished copy back down and checked: every page carries “Copy licensed to Miriam Wolfe · not for distribution” under the diagonal stamp. Viktor's says Viktor.

Tip: Processing result URLs expire after 1 hour — which is exactly why the pipeline chains them into the documents endpoint immediately instead of parking files anywhere.
3

What each copy buys you

  • Deterrence — a screenshot or printout of any page names its owner. Forwarding stops being free.
  • Per-person analytics — each copy is its own tracked document, so “Board Report — Miriam”'s sessions are Miriam's reading: every open, page and dwell time, plus the full history when you need it.
  • Surgical shutdown — one person's access ends by deactivating their link or archiving their document; nobody else notices. The revocation tutorial has the mechanics.

Keep the free plan's 3-tracked-documents limit in mind: per-recipient copies consume a document each, so this pattern is for the small, sensitive circle — board packs, term sheets, due-diligence material — not the hundred-lead campaign (that's per-recipient links on one document).

Where to go from here

Each half of this crossover has its own deep-dive.

Watermark conversationally The same stamping, done by asking Claude instead of scripting. Explore Master the kill switch Revoke, restore and expire access per person. Explore Hear about re-reads A confidential copy being re-opened is worth a ping. Explore

Related tutorials

Analytics Tracking Links

See If Clients Actually Read Your Monthly Reports

The report nobody reads is the retainer nobody renews. Tracked links per client sort the portfolio in one sweep — both Meridian stakeholders read cover to cover, Brightpath flicked for 15 seconds, Okafor never opened — and per-page data tells you whether your decision request was ever seen.

MCP Tracking Links

Mint PDF Tracking Links from ChatGPT

The share decision happens mid-conversation, not in a dashboard tab. The MCP server speaks to any client — including ChatGPT — so 'share the pricing guide with Elif' mints her tracked link inside the draft you were writing, and the same chat checks who read and kills a leaver's old link.

Tracking Links Analytics

Track Who Reads Your Press Kit

Twenty pitches, twenty attached kits, and a silence that could mean anything. Per-journalist links end the blindness: the full read plus asset download says she's writing, the fact-sheet return visit says offer the interview now, and the never-opened rows say re-pitch — not follow up.

Ready to see who reads?

Start free See pricing