Is Add Watermark free to use on PDFtan?

Yes, Add Watermark is completely free to use with up to 800 tasks allocated daily.

Are my files secure when using Add Watermark?

Yes. All uploads are processed in isolated memory workspaces and deleted permanently within minutes under our zero-retention guarantee.

What is the maximum file size supported for Add Watermark?

Add Watermark supports files up to 50MB.

Add Watermark Online Free — Fast & Secure PDF Processing

Fast & Effortless Workflow

How to Use Add Watermark Online

Transform, optimize, and process your documents in three simple steps directly in your web browser with zero software downloads.

Upload Your Document

Click the “Select .pdf” button or drag and drop your files directly into the secure upload area from your computer, smartphone, Google Drive, or Dropbox.

Configure & Process

Customize your conversion parameters, page sequence, or visual settings. Our isolated backend cluster executes the conversion with sub-second native C++ execution speeds.

Download & Auto-Purge

Instantly download your processed high-fidelity document. All uploaded files and temporary workspaces are permanently wiped automatically under our zero-retention guarantee.

Deep Specifications

Technical Specifications & System Attributes

Engine specifications, compatibility standards, and security parameters for Add Watermark.

Feature / Parameter	Specification Details
Supported Formats	Standard PDF, PDF/A, DOCX, XLSX, PPTX, JPG, PNG, WEBP (.pdf)
Processing Engine	Headless Native Linux Binary Cluster (QPDF, Ghostscript, LibreOffice, Tesseract OCR)
Max File Capacity	50 MB per task (Up to 1 files simultaneously)
Data Retention Policy	100% Zero-Retention Ephemeral RAM Workspace (Auto-deleted in 15-60 min)
Platform Availability	Cloud Web, Windows, macOS, Linux, Android, iOS, iPadOS

Core Architecture

Why Users Choose PDFtan for Add Watermark

Built from the ground up for high concurrency, lossless output, and absolute document confidentiality.

Sub-Second Execution

Bypass browser slowdowns. Tasks are processed by our native Linux binary worker pipelines in milliseconds.

Zero Permanent Storage

Strict privacy architecture. Uploaded files exist only in ephemeral storage and are automatically destroyed.

Lossless Vector Fidelity

Maintains original typography, embedded fonts, vectors, annotations, and formatting with zero quality loss.

Answers & Help

Frequently Asked Questions about Add Watermark

Common questions regarding security, task quotas, device compatibility, and file retention.

Yes! Add Watermark is 100% free to use on PDFtan. We provide generous daily task quotas (up to 800 free conversions daily) without watermarks, trial periods, or hidden subscriptions.