Thanks for compiling this list.
My interest is in free general-purpose timestamping service (e.g. stamping pdf, zip files) and this page was near the top of Google's search results, so a good starting point for a comprehensive list of freeTSA servers, but some of the links appear to be dead
dse200.ncipher.com/TSS/HttpTspServer : address could not be found for either the full URL or the base address dse200.ncipher.com.
timestamp.geotrust.com/tsa : has been retired by Symantec and replaced with sha256timestamp.ws.symantec.com/sha256/timestamp (see INFORMATIONAL | Discontinued Use of (Legacy) SHA1 RFC 3161 timestamp service - DigiCert) and appears to be a direct link to their RFC3161 timestamper and not a "landing" page.
Not 100% certain but it looks like the "timestamp.dll" links are direct RFC3161 timestamp server links designed to be used for code-signing only (possibly by Microsoft's SignTool).
For what I came to this page for the best current (1/19/2019) link for genuinely free general-purpose timestamping is freetsa.org. No time to go through all the links, but this of interest so I will update this comment as time allows.
Thanks again for the scholarship compiling this resource.
Double checked and it looks like the ncipher link is purely a timestamping server to be accessed via software like openssl and not a web site based service like freetsa, so simply putting the base address in a browser yields a "no page found" error, but it resolves fine in tracert.
Looks like http://timestamp.globalsign.com/scripts/timstamp.dll is now paid product.
Edit: The downtime of the verisign service was temporary, and it came back online a few hours after going down.
Digicert has announced that the former Verisign and Symantec time stamping services are deprecated; see [https://knowledge.digicert.com/alerts/migration-of-legacy-verisign-and-symantec-time-stamping-services.html] for their announcement. The three services timestamp.verisign.com/scripts/timstamp.dll, sha1timestamp.ws.symantec.com/sha1/timestamp, and sha256timestamp.ws.symantec.com/sha256/timestamp will go offline on or about Oct 31, 2019. They provide timestamp.digicert.com as the recommended replacement.