AS2 vs. SFTP: Comparing Business EDI Protocols

AS2 and SFTP are both used for secure EDI file transfer, but they solve different problems. AS2 is built for structured B2B data exchange with signed receipts, while SFTP is a secure file transfer protocol that works across EDI and many other business file workflows.

Electronic Data Interchange (EDI) has long been used for structured B2B data exchange, including purchase orders, invoices, shipping notices, claims files, financial records, and partner reports.

As more EDI workflows move through cloud systems, integration platforms, and managed file transfer tools, the transfer protocol becomes an important decision. The protocol affects security, partner setup, acknowledgments, automation, monitoring, and ongoing administration.

AS2 and SFTP are two of the most common options. AS2 was designed specifically for secure business data exchange over HTTP/S. SFTP is a secure file transfer protocol that runs over SSH and is widely used for EDI, batch transfers, partner uploads, reporting files, and internal system-to-system transfers.

This guide compares AS2 and SFTP for EDI so you can decide which protocol makes more sense for your trading partners, systems, and operational requirements.

For a broader comparison of EDI transfer options, see our full EDI protocol comparison.

AS2 and SFTP feature-by-feature comparison

Nature and purpose

AS2: AS2, or Applicability Statement 2, is a standard for securely exchanging structured business data over HTTP or HTTPS. It is commonly used for direct EDI exchange between trading partners and supports encrypted, signed message payloads.

SFTP: SFTP, or SSH File Transfer Protocol, is used to transfer and manage files securely over SSH. It is not EDI-specific, but it works well for EDI workflows where partners exchange files through controlled folders, scheduled jobs, integration platforms, or managed file transfer services.

For more detail on using SFTP specifically for EDI, see our guide to SFTP for EDI.

Encryption and security

AS2: AS2 can use encryption, digital signatures, and certificates to protect business messages. Security depends on correct certificate management, partner configuration, HTTPS setup, and the algorithms selected by the AS2 software.

SFTP: SFTP protects file transfers through SSH encryption. It can use password authentication, SSH key authentication, or both, depending on the platform and policy. The wider security model also depends on folder permissions, credential management, network rules, storage encryption, and audit visibility.

Authentication mechanisms

AS2: AS2 commonly uses X.509 certificates to identify trading partners and verify signed messages. Both sides need to manage certificate exchange, expiry, renewal, and trust.

SFTP: SFTP commonly uses usernames, passwords, and SSH public keys. In managed platforms, administrators can add controls around those credentials, such as access permissions, IP allowlists, home directory restrictions, and account-level security for the management dashboard.

Non-repudiation and acknowledgments

AS2: AS2’s major advantage is the signed Message Disposition Notification, or MDN. A signed MDN can confirm that the receiver received the message, verified its integrity, and authenticated the sender.

SFTP: SFTP does not include an AS2-style signed MDN. That does not make SFTP unsuitable for EDI, it just means acknowledgments need to be handled differently. Common options include EDI acknowledgment files, response files, application records, audit logs, webhook-triggered notifications, or processing confirmations from the EDI system.

If you specifically need signed MDNs for partner or legal reasons, AS2 is the better match. If you need secure EDI file exchange with flexible automation and transfer visibility, SFTP is often easier to operate, especially when used as part of a managed MFT platform that incorporates additional security and convenience features.

Integration and implementation

AS2: AS2 usually requires AS2-capable software on both sides, certificate setup, partner profile configuration, firewall and endpoint management, and MDN handling. That can be worthwhile when large trading partners require AS2, but it can add administration when you need to onboard many partners.

SFTP: SFTP is broadly supported by EDI translators, ERPs, middleware, iPaaS platforms, scripts, backup systems, and file transfer clients. For many teams, that makes implementation faster because partners and systems already know how to send and receive files over SFTP.

For a workflow-focused guide, read EDI Integration & SFTP.

Interoperability

AS2: AS2 requires both parties to support AS2. That works well in established EDI networks where AS2 is already mandated, but it can limit flexibility when partners use different systems or have lighter technical resources.

SFTP: SFTP is widely supported across operating systems, applications, managed file transfer tools, and automation platforms. This makes it practical for mixed partner environments where some partners use EDI systems and others need secure file upload or download access.

AS2 or SFTP: what’s the verdict?

The right choice depends first on partner requirements.

Choose AS2 when your trading partner requires it, when signed MDNs are mandatory, or when your EDI program depends on direct business document exchange with certificate-based signing and receipt handling.

Choose SFTP when the requirement is secure file-based exchange, easier partner onboarding, controlled folder access, broad system compatibility, and automation around uploads, downloads, processing, and reporting.

AS2 is often stronger for formal EDI networks that need signed receipts built into the transfer protocol. SFTP is often easier to manage when the transfer is one part of a wider workflow involving file storage, access control, integrations, webhooks, audit logs, and processing systems.

To make your choice easier, we’ve summed up the features of AS2 vs. SFTP in the comparison table below.

SFTP To Go: managed SFTP for EDI file exchange

SFTP To Go gives businesses a managed file transfer environment for secure EDI file exchange without maintaining their own SFTP server infrastructure.

For EDI workflows, SFTP To Go supports:

• Managed SFTP, FTPS, HTTPS, and Amazon S3
• Built-in cloud storage on AWS
• Credential-level access for users, partners, vendors, and systems, with folder and credential based user separation
• SSH key and password authentication for transfer credentials
• Web portal access with MFA and SSO options
• Folder permissions and home directory restrictions
• IP allowlisting for tighter access control
• Audit logs for file and user activity
• Webhooks for file upload, download, and deletion events
• REST API support for credentials, SSH keys, webhooks, share links, audit logs, and audit log exports

SFTP To Go it gives you a managed SFTP and MFT environment that's ideal for file-based EDI, with controls for partner access, storage, automation hooks, monitoring, and operational visibility.

If you need event-driven EDI processing after a file lands, see Real-time EDI Processing over SFTP Using Webhooks.

In conclusion

AS2 and SFTP are both valid secure transfer options for EDI, but they are not interchangeable.

AS2 is purpose-built for structured B2B document exchange and has a strong advantage when signed MDNs and certificate-based non-repudiation are required.

SFTP is broader. It is widely supported, easier to integrate into many file-based workflows, and practical for EDI exchanges where files need to move securely between partners, applications, and processing systems.

If your trading partner requires AS2, use AS2. If your EDI workflow can run over secure file transfer and you want less infrastructure work, broader compatibility, and better control around folders, users, automation, and logs, managed SFTP is often the more practical choice.

SFTP To Go helps teams run EDI file exchange over managed SFTP, FTPS, HTTPS, and Amazon S3 access, with storage, permissions, audit logs, APIs, and webhooks built around the transfer process.

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