PDF Text Watermark API

API ID 12964

Add professional text watermarks to any PDF document with full control over position, opacity, font size, color, and rotation. Stamp documents with CONFIDENTIAL, DRAFT, your brand name, or any custom text across every page. The watermark is rendered as selectable, high-quality text with Unicode support. Ideal for branding, copyright protection, document status marking, and legal workflows. Upload a PDF and receive a downloadable watermarked file.

API Documentation

Endpoints

Request

Add a text watermark to a PDF. Attach the PDF in the file field and set the watermark text plus optional styling. Returns a JSON object with a downloadable URL to the watermarked PDF.

Endpoint ID: 25882
POST https://docs.zylalabs.com/api/12964/pdf+text+watermark+api/25882/add+text+watermark
INPUT PARAMETERS

Add Text Watermark — Endpoint Features

Object Description
text Optional REQUIRED. The watermark text stamped on every page (1-100 characters). Example: CONFIDENTIAL.
position Optional Watermark position (optional, default 'center'). Options: center, top-left, top-right, bottom-left, bottom-right.
opacity Optional Watermark transparency (optional, default '0.3'). 0.0 = invisible, 1.0 = fully solid.
font_size Optional Font size in points (optional, default '24'). Allowed range: 8 to 72.
color Optional Watermark color as a hex code (optional, default '#000000'). Example: #FF0000 for red.
rotation Optional Rotation angle in degrees (optional, default '0'). Range -180 to 180. Use 45 for a diagonal stamp.
Request Body Required File Binary

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

text
position
opacity
font_size
color
rotation
API EXAMPLE RESPONSE
JSON
{"success":true,"url":"https://pub-6db99bab215e44889f46c4b2a619f8c5.r2.dev/watermarked/20260619/f977168b-1b94-4749-a97a-0e90c2cc6af3.pdf","watermark_type":"text","pages_watermarked":5,"processing_time":"673ms"}
Add Text Watermark — CODE SNIPPETS

    curl --location 'https://zylalabs.com/api/12964/pdf+text+watermark+api/25882/add+text+watermark?text=CONFIDENTIAL BRO&rotation=Optional' \
    --header 'Content-Type: application/json' \ 
    --form 'image=@"FILE_PATH"'

API Access Key & Authentication

After signing up, every developer is assigned a personal API access key, a unique combination of letters and digits provided to access to our API endpoint. To authenticate with the PDF Text Watermark API simply include your bearer token in the Authorization header.

Headers
Header Description
Authorization Required Should be Bearer access_key. See "Your API Access Key" above when you are subscribed.

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Overview

The PDF Text Watermark API allows developers to add customizable text watermarks to PDF documents through a simple API request. Upload a PDF file, specify the watermark text, and configure its appearance using options such as position, opacity, font size, color, and rotation. The API processes the document and returns a downloadable version containing the watermark applied across all pages.

Watermarks can be used to identify document status, indicate ownership, display copyright notices, apply company branding, or mark documents for internal and external distribution. Common examples include "CONFIDENTIAL", "DRAFT", "INTERNAL USE ONLY", company names, project identifiers, legal notices, and other custom text labels.

The API supports configurable watermark placement, allowing text to appear in the center of the page or in one of the page corners. Opacity settings can be adjusted to ensure the watermark remains visible while preserving the readability of the original document. Rotation controls make it possible to create diagonal stamps commonly used for confidential and draft documents.

Watermark text is rendered directly into the PDF and supports Unicode characters, making it suitable for multiple languages and international document workflows. Font size and color can be customized to match branding requirements or document policies.

Common use cases include:

  • Marking confidential documents

  • Adding draft or review status indicators

  • Applying company branding to PDFs

  • Copyright and ownership labeling

  • Legal and compliance workflows

  • Contract and agreement management

  • Internal document distribution

  • Invoice and report identification

  • Educational and publishing platforms

  • Document archiving and record management

Features:

  • Add text watermarks to PDF documents

  • Apply watermarks across all pages

  • Custom watermark text

  • Adjustable position settings

  • Configurable opacity levels

  • Custom font size controls

  • Custom text color selection

  • Rotation angle support

  • Unicode character support

  • Downloadable PDF output

  • JSON response format

  • HTTPS-based API access

The API accepts PDF files as multipart form-data and returns structured JSON containing a download URL for the processed document. It can be integrated into document management systems, workflow automation platforms, web applications, mobile applications, business software, and file processing services that require PDF watermarking functionality.

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