Digitally Sign Any File in Your Browser: Without Uploading Files or Installing Software — 100% Local, Private, and Secure.

Secure Digital Document Signing Without Uploading Files or Installing Software

Digital signatures are a foundational requirement for secure document exchange, software distribution, compliance workflows, and data integrity validation. However, most online signing tools introduce privacy risks by uploading files to remote servers or forcing user accounts and installations.

This browser-based Digital Document Signer solves that problem by performing all cryptographic operations locally using the Web Cryptography API. Files never leave the device, no software is installed, and no registration is required.

What This Tool Does

This tool enables users to:

• Generate secure cryptographic key pairs
• Digitally sign any file type
• Verify document authenticity and integrity
• Detect tampering with mathematical certainty

All operations occur entirely inside the browser, ensuring maximum privacy and security.

Key Privacy and Security Advantages

1. Local-Only Data Processing
All keys, files, and signatures are generated and processed locally in the browser. Nothing is uploaded, stored, or transmitted to a server.
2. No Registration or Accounts
The tool can be used immediately without creating an account or sharing personal information.
3. No Downloads or Installations
Runs directly in modern browsers. No plugins, no executables, no dependencies.
4. Private Keys Never Leave the Device
The private signing key remains under full user control and is never transmitted over the network.
5. Industry-Standard Cryptography
Uses RSA-PSS (2048-bit) with SHA-256 via the Web Cryptography API — a modern and secure standard.

What Types of Files Can Be Signed?

The signing process operates on raw binary data, making it format-agnostic. This includes:

• PDFs, DOCX, XLSX, TXT
• JSON, XML, HTML
• Images (PNG, JPG, GIF)
• Audio and video files (MP3, MP4)
• ZIP archives and software binaries

If the file can be opened in a browser, it can be signed.

How Digital Signature Verification Works

Signature verification requires only three items:

• The original file
• The digital signature file (.sig)
• The signer’s public key

If verification succeeds, the file is guaranteed to be:

• Authentic
• Untampered
• Signed by the holder of the corresponding private key

Any modification to the file—even a single byte—will invalidate the signature.

Ideal Use Cases

• Secure document exchange
• Contract verification
• Open-source file distribution
• Compliance and audit trails
• Software integrity checks
• Sensitive data sharing

Why This Approach Matters

Many “free” online signing tools trade convenience for privacy by storing files on external servers. This tool takes the opposite approach: privacy by design.

By leveraging client-side cryptography, it ensures:

• Zero data leakage risk
• Full user ownership of cryptographic keys
• Transparent and verifiable security behavior

Try the Tool Instantly

The Digital Document Signer works instantly in the browser:

• No sign-up
• No installation
• No file uploads
• No tracking of document content

Try it now and sign or verify documents securely in seconds.