June 12, 2026

AS2 vs SFTP: how to answer when buyers ask

Procurement RFPs increasingly ask "do you support AS2 and SFTP?" as if they are interchangeable. They are not — they solve different integration problems. Giving a crisp comparison wins technical evals; hand-waving sends buyers to a competitor who maps protocols to use cases.

When SFTP is the right answer

SFTP fits batch file exchange with partners who want a familiar folder metaphor: drop files in /outbound, poll /inbound. Ops teams script it with cron, rsync, or native MFT jobs. Authentication is SSH keys or passwords; encryption is TLS inside SSH. Best for general B2B payloads — invoices, reports, flat files — where MDN-style delivery receipts are nice-to-have, not contractual.

When AS2 is non-negotiable

Retail, healthcare, and automotive supply chains often mandate AS2 because of non-repudiation: signed payloads, encrypted transport, and Message Disposition Notifications proving receipt. EDI over AS2 is a standard, not a preference. If your buyer's spec cites RFC 4130 or requires MDN within 15 minutes, SFTP is a compliance gap regardless of how fast your server is.

Security questionnaire angles

Buyers ask both protocols in the same breath to detect shadow infrastructure — an official MFT platform plus a forgotten AS2 gateway on a Windows VM. Your answer should be one control plane, one audit log, adapters for both. Certificate management for AS2 (signing, encryption, partner trust stores) must be documented alongside SSH key rotation for SFTP.

Operational trade-offs

SFTP endpoints scale with standard load balancers and firewall rules on port 22. AS2 needs HTTP/S endpoints, certificate expiry monitoring, and partner-specific AS2 IDs — higher setup cost per trading partner, lower ambiguity at settlement time. Running both on separate silos doubles patching, logging, and evidence-export work.

Inventory every live endpoint with the protocol endpoint inventory before you respond to the RFP. xEvolve includes AS2 and SFTP in the same Environment with unified audit — no per-protocol license tiers.