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Apply Watermark to PDF File API

What it does

PDF Watermark adds a text watermark to a PDF and returns the modified file as binary output. Send a PDF plus the watermark text, and you can control how it appears with optional opacity, font size, position, and rotation.

Use it when you need to mark internal documents, label draft versions, or stamp files before sharing them with customers or partners. The input is a single PDF file up to 20 MB, along with the text you want placed on the page.

The response is the watermarked PDF file itself, so it fits cleanly into document workflows where you need to store, download, or forward the updated file without extra parsing. If you are building a document pipeline, PDF Watermark gives you a simple way to add consistent branding or status labels to outgoing PDFs.

POST
Add a text watermark to a PDF
https://api.eu.apyhub.com/freedailypro/apply-watermark-to-pdf-file/watermark

QUICKSTART

GUIDE

Quickstart

Upload a PDF and add watermark text to generate a watermarked file.

curl -X POST "https://api.eu.apyhub.com/freedailypro/apply-watermark-to-pdf-file/watermark" \
  -H "apy-token: $APY_TOKEN" \
  -F "file=@/path/to/file.pdf" \
  -F "text=Confidential"

What you'll get back

Returns a binary file (string with format: binary) — the watermarked PDF.

<binary file>
TRY ITLIVE · 10 ATOMS
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Max 100MB total per request (all files combined). Larger? Use this API's URL-based endpoint instead, if it has one.
body*
The PDF. Up to 20 MB.
Watermark text
0 to 1
Font size in points
Position, for example center

About this endpoint

What it does

Adds a text watermark to a PDF by taking an uploaded PDF file and watermark text, then returning the resulting PDF as a binary file.

Request Body

ParameterTypeMandatoryDescription
fileStringYesThe PDF file to watermark. Binary upload. Up to 20 MB.
textStringYesWatermark text.
opacityNumberNoWatermark opacity, from 0 to 1.
fontSizeNumberNoWatermark font size in points.
positionStringNoWatermark position, for example center.
rotationDegreesNumberNoWatermark rotation in degrees.

Response

Returns a binary file containing the watermarked PDF.

ParameterTypeMandatoryDescription
fileStringYesThe generated PDF file returned as binary output.

Max 100MB total per request (all files combined). Larger? Use this API's URL-based endpoint instead, if it has one.

▣ COMMON ERRORS

Errors any endpoint can return

400bad_request

Required parameter missing or malformed body.

401unauthorized

API key missing, revoked, or not authorized for this service.

429rate_limited

Your plan's per-second rate exceeded. Retry with exponential backoff.

503upstream_busy

Backend temporarily unavailable. Try again in a few seconds.

Similar APIs

Closest matches in the catalog based on this service.

CALLPDF Watermark API: Add Text or Image WatermarksApyHubCALLApply Watermark and Footers on PDF APIApyHubCALLApply Invisible Text Watermark on Image APIDosvak LLCCALLApply Watermark on Images APIApyHub

From the blog

Reads that touch this API.

Securing Your Documents: Exploring the Benefits & Use Cases of PDF WatermarkingJul 9, 2026Best PDF Watermark APIs in 2026: Adobe, pdfRest, Nutrient, iLoveAPI, ConvertAPI and ApyHub ComparedSep 29, 2026Exploring Video Watermarking: Techniques and BenefitsSep 9, 2026Top Video Watermarking APIs You Should Explore in 2026Jul 30, 2026