Singapore's e-signature framework rests on the Electronic Transactions Act 2010 (Cap. 88) ("ETA"), which implements the UNCITRAL Model Law on Electronic Commerce and Singapore's accession to the UN Convention on the Use of Electronic Communications in International Contracts. The ETA takes a technology-neutral, functional-equivalence approach: it doesn't mandate any particular signature technology, focusing instead on whether a method reliably identifies the signer and indicates their intent to sign.

Under Section 8, an electronic signature satisfies a legal signature requirement where a method is used to identify the signer and indicate their intention, and that method is either as reliable as appropriate for the circumstances or is proven in fact to have fulfilled those functions. The ETA also recognizes a higher tier, the Secure Electronic Signature, for methods that are unique to the signer, capable of identifying them, created under their sole control, and linked to the record so that any later alteration is detectable. Secure Electronic Signatures carry legal presumptions of authenticity, integrity, and signing intent, which shifts the burden onto a challenger to rebut them. A third tier, the PKI-based Digital Signature verified through an accredited Certification Authority (Netrust Pte Ltd is Singapore's principal accredited CA), functions as Singapore's closest analogue to a qualified electronic signature and is generally reserved for select government, regulatory, and construction-sector filings.

The ETA's First Schedule excludes certain categories from electronic execution: wills, trusts, powers of attorney and indentures (with narrow exceptions for lasting powers of attorney and implied or constructive trusts), and contracts for the sale or disposal of real estate or the conveyance of interests in immovable property. Negotiable instruments and bills of lading were historically excluded too, though the Electronic Transactions (Amendment) Act 2021 introduced an electronic transferable records regime, adopting the UNCITRAL Model Law on Electronic Transferable Records (MLETR), which allows trade documents like bills of lading and warehouse receipts to be issued electronically within a compliant system. Parties remain free to contractually exclude electronic signatures or impose additional authentication requirements for a given transaction.

Singapore courts have consistently applied a functional approach to signatures: in M Integrated Transware Pte Ltd v Schenker Singapore (Pte) Ltd, the High Court held that what matters is whether a mark fulfills the function of a signature rather than its particular form, reinforcing that ordinary electronic signatures carry real evidentiary weight even outside the "secure" tier. For most SaaS and B2B use cases, this means standard or secure electronic signatures are enforceable with confidence, and stronger authentication (identity verification, timestamping, a tamper-evident audit trail) meaningfully improves evidentiary strength in a dispute.