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We released our FTP and SFTP testing tools for free
Published 2026-06-16 05:33:26.335994 by Carsten Blum
For years we've operated large numbers of FTP, FTPS and SFTP servers. Every time we deployed a new environment, migrated infrastructure or investigated customer issues, we found ourselves running the same set of checks over and over again. Does DNS resolve correctly? Is the port reachable? Does TLS work? Is the SSH fingerprint what we expect? Can users actually authenticate?
Eventually we built a collection of internal tools to answer those questions quickly. Over time those tools became part of our standard deployment and validation process for every ftpGrid edge node. Today we're making them available to everyone for free.
The goal is simple: if you're running your own FTP, FTPS or SFTP infrastructure, you should have access to the same diagnostics and validation tools we use ourselves.
Why we built these tools
Most FTP and SFTP problems are surprisingly simple once you identify where things fail. The challenge is determining whether the issue is DNS, networking, authentication, TLS, SSH configuration or server capabilities.
Instead of manually checking each layer, we wanted tools that could perform a complete validation sequence automatically.
Typical issues include:
Incorrect DNS records
Closed firewall ports
Broken TLS certificates
SSH fingerprint mismatches
Authentication failures
Misconfigured passive mode
Unsupported protocol features
A few seconds of testing can often save hours of troubleshooting.
FTP Connection Test Tool
Our FTP Connection Test Tool performs a complete end-to-end validation of an FTP or FTPS server. Rather than simply checking whether a port is open, it verifies multiple aspects of the server configuration.
The goal is to answer a simple question:
"Can a client actually connect and use this server successfully?"
Checks include:
DNS Resolution
TCP Connectivity
FTP Banner Detection
Authentication Test
Passive Mode (PASV)
FTP Feature Discovery (FEAT)
System Information (SYST)
Server Status (STAT)
Explicit FTPS (AUTH TLS)
TLS Certificate Inspection
Anonymous Login Verification
This makes it useful for both troubleshooting and deployment validation.
SFTP Connection Test Tool
SFTP environments have their own unique set of challenges. SSH fingerprints, subsystem configuration and authentication issues are all common sources of frustration.
Our SFTP Connection Test Tool validates the entire connection workflow.
Checks include:
DNS Resolution
TCP Connectivity (Port 22)
SSH Banner Detection
SSH Host Key Detection
SSH Fingerprint Verification
SFTP Authentication Test
SFTP Subsystem Availability
This provides a quick way to verify whether an SFTP server is configured correctly before users start reporting problems.
SSH Fingerprint Lookup
One of the most overlooked aspects of SFTP security is server identity verification. Users often connect to servers without verifying that they are talking to the correct endpoint.
SSH fingerprints exist specifically to solve this problem.
The SSH Fingerprint Lookup tool provides:
SSH Host Key Algorithm
SHA256 Fingerprint
Public Host Key
Key Security Rating
SSH Service Availability
This can be particularly useful when onboarding new partners or validating infrastructure changes.
FTP Feature Decoder
Many FTP servers advertise supported capabilities through the FEAT command. Unfortunately, the resulting output can be difficult to interpret unless you're familiar with the protocol.
The FTP Feature Decoder translates technical protocol features into plain English.
Supported feature explanations include:
AUTH TLS – Explicit FTPS support
MLST / MLSD – Machine-readable directory listings
MDTM – File modification timestamps
SIZE – File size queries
UTF8 – UTF-8 filename support
MODE Z – Compressed transfers
REST STREAM – Resume interrupted transfers
MFMT – Update file timestamps
TVFS – Virtual file system support
MD5 / MMD5 – File integrity verification
This makes it much easier to understand what a server actually supports.
Additional infrastructure tools
Beyond FTP and SFTP-specific diagnostics, we also released several supporting tools that help validate the surrounding infrastructure.
Many connectivity issues originate outside the file transfer service itself.
Additional tools include:
Together these tools help verify the entire stack rather than just the application layer.
Useful for self-hosted environments
Although we operate ftpGrid as a managed service, these tools were originally built for validating infrastructure. They are just as useful for self-hosted environments as they are for managed platforms.
Whether you're running a single server or a larger deployment, visibility is important.
Common use cases include:
New server deployments
Infrastructure migrations
Security reviews
Customer troubleshooting
Partner onboarding
Change validation
Good diagnostics are valuable regardless of where the server runs.
File transfer is becoming more than storage
One thing we've observed over the years is that file transfer infrastructure increasingly acts as an integration layer rather than simple storage.
Files trigger workflows. Systems exchange data. Applications react to events.
Modern file workflows increasingly involve:
Secure file transfer
REST APIs
Webhooks
Automation
Cloud integrations
Audit logging
If that topic interests you, you may also enjoy:
Why we decided to release them publicly
The original intention was never to build public tools. We simply needed a reliable way to validate our own infrastructure and troubleshoot customer issues quickly.
Over time, however, it became clear that many administrators, consultants and developers face exactly the same challenges.
If these tools help someone:
Deploy a server faster
Troubleshoot an issue quicker
Improve security
Validate a migration
Verify a configuration
Then releasing them was worth it.
Try the tools
All tools are completely free and available without creating an account. Whether you're running a self-hosted server, evaluating a managed platform or simply troubleshooting an integration, we hope they save you a few hours of frustration.
Explore the full collection here:
Check out the ftpGrid free test tools