There is no single universal witness rule that applies to every document simply because the signing is online.
Some documents, statutes, attorneys, lenders, title companies, estate plans, or receiving organizations may impose qualifications on witnesses, including restrictions involving financial interest, family relationships, beneficiary status, or other conflicts.
A person who is technically available and has valid identification is not automatically a qualified witness for every transaction.
iRemoteNotary can help coordinate the session, but the signer or document preparer should confirm substantive witness qualifications when they depend on the particular instrument or transaction.
Some government forms have their own requirements that are separate from ordinary witness rules. For example, Form DS-3053 follows separate U.S. Department of State instructions and does not ordinarily require separate subscribing witnesses.