The e-signature market today is full of incredible signing platforms. Right now, some of the biggest players are:
DocuSign
Adobe Sign
SignNow
PandaDoc
HelloSign
Right now, the e-signature market is also changing. Many key players are expanding their offering beyond digital signatures.
HelloSign, now a Dropbox subsidiary, integrates with the storage platform for easy signing. PandaDoc offers document creation tools that work well for proposals and contracts. Adobe Sign combines e-signing with PDF editing tools.
As you might expect, the pricing for each of these services varies with their service offering, so be sure to take a close look at everything before you commit to a plan.