Help for ftp:// (FTP) links on English Wikipedia.

FTP links (ftp://) existed before the invention of the World Wide Web. Prior to the 1990s, it was the ubiquitous method of transferring files over the Internet. As the web (http://) gained dominance, FTP was still used by many institutions because of established practice and the cost of changing systems. Nevertheless, FTP has serious shortcomings from a security standpoint and incompatibilities between FTP servers/clients. By 2021, most modern web browsers ceased support for the FTP protocol. For most web users clicking a ftp:// now results in a page not found. At the same time many institutions have migrated to https:// and so each year the number of dead FTP links increases and working FTP links are fewer. On English Wikipedia, over 90% of the existing FTP links are dead, and many of those that are still live are gradually dying off.

• Hybrid: A HTTPS interface (or gateway) is when the FTP server also supports https:// allowing it work in a web browser. Not all FTP servers support the https:// interface.

Example:

• ftp://ssd.jpl.nasa.gov/pub/ssd/horizons_batch.txt
• https://ssd.jpl.nasa.gov/ftp/ssd/horizons_batch.txt

In this example the directory structure is not quite the same for the ftp vs. https version; this is a choice of the operators of the server.

• Pure: Pure FTP are ftp:// links that have no interface. They are only work with dedicated FTP client software.

The way to determine is try replacing ftp:// with https://

Pure FTP links can sometimes be saved at aweb archive provider, like the Wayback Machine.

If the link has or had a HTTPS gateway, it may have been archived with the ftp:// version of the URI - in these cases cite it with{{cite web}}. For the|url= use the https:// version of the link, and for|archive-url= use whatever archive URL works, either the one using ftp:// or https://

To cite FTP, follow these steps:

1. Check if the FTP has an HTTPS interface. Replace the ftp:// portion with https:// and see if it works. If so, use{{cite web}} or a related template, with|url= set to the https:// version. Also, try checking with the organization that runs the server, or try opening the ftp server with an appropriate client and reading any login messages.
2. If it doesn't work it means one of two things: the FTP link is "pure" and can only be accessed with an FTP client. Or the FTP link is dead.
3. Using a FTP client check if the link is working. If it is working, cite it with{{Cite FTP}}.
4. If not working, you have a number of choices: 1. Delete the citation entirely 2. Google around for the same data located elsewhere on the web 3. Log into the FTP site and search for alternative locations within the FTP tree. 4. If all else fails and you still want to retain a non-working FTP link: change it to a{{Cite FTP}} template and add|url-status=dead.

SeeComparison of FTP client software. Software is available on multiple platforms for GUI or command-line. Note that some FTP clients are not compatible with some FTP servers. This can give the false impression that a FTP link is dead. It is recommended to use an advanced modern client that can auto-negotiate such aslftp.