Add Signature to Images

Add digital signatures to images. Draw or upload your signature. Perfect for documents, certificates and professional use. High-quality output.

100% client-side — your files never leave your browser.

Upload an image to get started

Click anywhere to browse, or paste directly with ⌘V / Ctrl+V

You can also drag & drop files here.

Supports PNG, JPG, WebP, AVIF, GIF, BMP, and ICO files.

Try a sample image

No upload required
Comprehensive Guide

Digital Signature Watermark & Transparent Signature Tool

Apply digital signatures and handwritten author marks onto contracts, photos, and artwork.

How It Works: Step-by-Step Instructions

1. Upload Document or Artwork

Load the file you wish to sign.

2. Draw or Upload Signature

Draw your signature on canvas or upload a scanned transparent signature.

3. Position & Scale

Place the signature precisely where needed and adjust ink color.

4. Download Signed File

Export your securely signed file.

Technical Specifications & Architecture

BitNexa combines HTML5 Canvas, WebAssembly, and modern GPU acceleration to execute professional-grade graphics algorithms directly in the browser sandbox.

Smooth Bézier Vector Inking

Captures touch and mouse strokes using smoothing algorithms for realistic handwriting.

Pro Tips & Best Practices

  • ✓Draw signatures using a stylus or touchscreen for the most natural handwritten curve.

Frequently Asked Questions

Common questions about this tool, file formats, and client-side processing.

No! All signature processing is strictly confined to your local browser session for complete privacy and fraud protection.

100% Client-Side Privacy Guarantee

Your files never upload to our servers. All operations execute directly in your web browser.

Zero Cloud Storage • Zero Logging