SFTP, FTPS, and FTP are three distinct protocols for transferring files over a network. FTP is the oldest and least secure, transmitting data in plain text. FTPS adds TLS/SSL encryption to FTP. SFTP is an entirely separate protocol built on SSH that provides the strongest security and simplest firewall configuration. For most modern use cases, SFTP is the recommended choice.
Quick Comparison
| Feature | FTP | FTPS | SFTP |
|---|---|---|---|
| Encryption | None | TLS/SSL | SSH (AES, ChaCha20) |
| Default Port | 21 | 21 (explicit) / 990 (implicit) | 22 |
| Ports Required | 2+ (control + data) | 2+ (control + data) | 1 (single connection) |
| Authentication | Username/password (plain text) | Username/password + certificates | Password, SSH keys, or both |
| Firewall Friendly | No | Difficult | Yes |
| Certificate Management | None | Required (TLS certificates) | None (uses SSH host keys) |
| Protocol Family | FTP | FTP + TLS | SSH |
FTP: The Legacy Protocol
FTP (File Transfer Protocol) was defined in 1971 and standardized in RFC 959 in 1985. It was designed for an era when network security was not a concern. FTP transmits everything in plain text — including usernames and passwords — making it trivial for anyone on the network path to intercept credentials and file contents.
FTP also uses a dual-connection architecture: a control connection on port 21 for commands and a separate data connection (active or passive mode) on dynamic ports for file transfers. This design creates significant firewall and NAT traversal challenges.
Verdict: FTP should not be used for any transfers involving sensitive data. It is effectively deprecated for production use.
FTPS: FTP with TLS Encryption
FTPS (FTP Secure) adds TLS/SSL encryption on top of the FTP protocol. It comes in two forms:
- Explicit FTPS — The client connects on port 21 and requests TLS encryption via the AUTH TLS command. This is the more common and recommended mode.
- Implicit FTPS — The connection starts encrypted on port 990. This mode is older and less commonly used today.
While FTPS encrypts the data in transit, it inherits FTP's dual-connection architecture. The data channel uses dynamic ports, which means you need to open a range of ports in your firewall. TLS certificate management adds operational overhead — certificates must be purchased or generated, installed, and renewed regularly.
Verdict: FTPS is a reasonable choice when you must support legacy FTP clients but need encryption. However, it is more complex to configure and maintain than SFTP.
SFTP: The Modern Standard
SFTP (SSH File Transfer Protocol) is not an extension of FTP. It is a completely separate protocol that runs over SSH. This distinction is important: SFTP was designed with security as a fundamental requirement, not as an afterthought.
SFTP uses a single encrypted connection on port 22 for all operations. There are no separate data channels, no dynamic port ranges, and no certificate management. Authentication can use passwords, SSH keys, or both.
Verdict: SFTP is the best choice for nearly all file transfer needs. It is more secure, simpler to configure, and easier to manage than both FTP and FTPS.
When to Use Each Protocol
Use SFTP when:
You need secure file transfer (which is almost always). SFTP is the default recommendation for new projects, automation, cloud environments, and compliance-sensitive workloads.
Use FTPS when:
You need to support legacy FTP clients that cannot use SFTP, or when a trading partner specifically requires FTPS. Some industries with older systems still mandate FTPS.
Avoid FTP:
Do not use plain FTP for anything involving sensitive data, credentials, or compliance requirements. If you are currently using FTP, plan a migration to SFTP.
Key Takeaways
- FTP is unencrypted and should not be used for sensitive data.
- FTPS adds TLS encryption to FTP but inherits its firewall complexity and requires certificate management.
- SFTP is a separate protocol built on SSH — encrypted by default, single port, and supports key-based authentication.
- For new projects, SFTP is the recommended protocol in virtually all scenarios.
- A managed SFTP hosting service eliminates the need to run and maintain your own SFTP server.