Signaturely - Super simple eSignature software

GetAccept - GetAccept is a Sales tool for electronic signatures and sales document automation.

Woleet Sign - eSignatures secured by Bitcoin

HTMLCSS to Image API - Convert HTML to an image (jpg, png, webp). Renders images exactly like Google Chrome. Works with PHP, JavaScript, Ruby, .NET and more.

SignEasy for Gmail - Sign documents or collect signatures directly within Gmail

Authorgraph - Enabling authors to sign e-books for their readers.