Add Watermarks to PDFs with the API2PDF Watermark API

API2PDF now supports adding watermarks to PDF files with a dedicated PDF Watermark API endpoint.

Developers can provide a PDF and use API2PDF to apply a watermark programmatically as part of an automated document workflow.

The new endpoint is:

POST /pdf/watermark

This makes API2PDF a simple PDF Watermark API for applications that need to add watermarks to PDFs without installing, operating, or scaling their own PDF manipulation infrastructure.

Add a Watermark to a PDF with cURL

Here is an example using cURL:

curl -X POST "https://v2.api2pdf.com/pdf/watermark" \
  -H "Authorization: YOUR-API-KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com/document.pdf",
    "text": "CONFIDENTIAL"
  }'

Replace YOUR-API-KEY with your API2PDF API key and provide the URL of the PDF you want to watermark.

API2PDF retrieves the PDF, applies the requested watermark, and produces a new watermarked PDF.

PDF Watermark API

Watermarks are commonly used to communicate the status, ownership, confidentiality, or intended use of a document.

For example, applications may need to automatically mark PDFs as:

  • CONFIDENTIAL

  • DRAFT

  • INTERNAL USE ONLY

  • SAMPLE

  • COPY

  • APPROVED

  • DO NOT DISTRIBUTE

Instead of manually editing each PDF, an application can add the appropriate watermark automatically using an API request.

A typical workflow looks like:

PDF → API2PDF Watermark API → Watermarked PDF

Add Watermarks to PDFs Programmatically

Adding a watermark manually is straightforward when dealing with one document. It becomes a different problem when an application needs to process hundreds or thousands of PDFs automatically.

A PDF watermark REST API allows the watermarking process to become part of the application's normal document workflow.

For example:

Generate PDF → Add Watermark → Store PDF → Send to Customer

Or:

Upload PDF → Add CONFIDENTIAL Watermark → Store Document

This can be useful for SaaS applications, document management systems, reporting systems, contract workflows, internal business applications, and automated document-generation platforms.

Automate PDF Watermarking

The API2PDF watermark endpoint can be integrated into automated workflows where a PDF's watermark changes based on its status.

For example, a document workflow might use:

DRAFT while a document is being reviewed.

CONFIDENTIAL when a document contains sensitive business information.

APPROVED after a document completes an approval workflow.

SAMPLE for PDFs generated for evaluation or demonstration purposes.

Because watermarking is exposed through a REST API, these decisions can be made automatically by your application.

PDF Watermark API Use Cases

Common uses for a PDF watermark API include:

  • Adding CONFIDENTIAL watermarks to PDFs

  • Adding DRAFT watermarks to PDFs

  • Watermarking reports

  • Watermarking contracts

  • Watermarking invoices

  • Watermarking certificates

  • Watermarking generated documents

  • Document approval workflows

  • Document management systems

  • SaaS document generation

  • Automated PDF processing

  • Internal business workflows

  • Protecting preview or sample documents

The endpoint can be combined with API2PDF's existing PDF generation and manipulation APIs to build complete automated document workflows.

Combine PDF Generation and Watermarking

API2PDF can generate PDFs from HTML, URLs, and Markdown, which means watermarking can be added as a second step after PDF generation.

For example:

HTML → PDF → Watermark

Web Page → PDF → Watermark

Markdown → PDF → Watermark

This makes it possible to generate a document and immediately apply a status or classification watermark before the PDF is delivered to the user.

An application generating reports, for example, could create a PDF and automatically watermark preliminary versions as DRAFT.

Once the report is finalized, the application could generate the final version without the draft watermark.

PDF Watermarking Without Running PDF Infrastructure

PDF manipulation often requires native libraries, command-line utilities, or dedicated document-processing services.

For applications running in containers, serverless environments, or distributed infrastructure, maintaining those dependencies can add unnecessary complexity.

API2PDF exposes PDF watermarking through a standard HTTP API:

PDF + Watermark → API2PDF → Watermarked PDF

Your application makes the request and API2PDF handles the PDF processing.

PDF Watermark API Endpoint Reference

Method: POST

Endpoint:

https://v2.api2pdf.com/pdf/watermark

Authentication:

Authorization: YOUR-API-KEY

Content-Type:

Content-Type: application/json

Provide the source PDF and watermark configuration in the request body.

API2PDF then processes the document and returns the resulting watermarked PDF.

Getting Started

If you already use API2PDF, you can start adding watermarks to PDFs using:

POST https://v2.api2pdf.com/pdf/watermark

The endpoint can be used independently or combined with API2PDF's PDF generation and document-processing endpoints to create larger automated workflows.

Whether you're adding CONFIDENTIAL to internal reports, DRAFT to documents awaiting approval, or SAMPLE to preview documents, the PDF Watermark API provides a simple way to add watermarks to PDFs programmatically.

For the complete request specification and available watermark options, see the API2PDF v2 documentation.