Are online signatures legally binding?
ESIGN, UETA and eIDAS in plain words, and what an audit certificate actually proves.
In the United States, the ESIGN Act of 2000 and the state-level UETA say an electronic signature has the same legal effect as a handwritten one, as long as the signer intended to sign, consented to doing it electronically, and the record is kept. In the European Union, eIDAS sets three levels: simple, advanced and qualified. Most everyday documents, leases, NDAs, offer letters, engagement letters, only need a simple electronic signature.
A signature you draw and place yourself with the free Sign PDF tool is a simple electronic signature. It is fine for documents where nobody is likely to dispute who signed. It carries no evidence beyond the picture on the page.
A signature request adds the evidence: each recipient gets a unique link, the service records the email, IP address, timestamp and the document's fingerprint at signing time, and the finished file ships with an audit certificate that can be checked later. That is what makes a signature hold up when someone says "that is not mine". BettrPDF plans this for Pro; it is not live yet.
What no e-signature tool can do is decide for you whether a specific document may be signed electronically. Wills, some real-estate transfers and court filings have their own rules by jurisdiction. When in doubt, ask a lawyer, and keep the audit trail.