At the TNC25 FileSender meeting, Kenjiro Yamanaka of the National Institute of Informatics (NII), the Japanese NREN, presented a global extension of FileSender. This initiative enables international file sharing by allowing FileSender servers worldwide to collaborate and transfer files quickly from the sender’s FileSender server to one near the receiver. NII launched a trial service of Global FileSender on October 31, 2025. Here, we outline its value, practical challenges, and current development status.
FileSender is open source software to deliver a service for easy and secure transfer of large files through a trusted intermediary, often the NREN. The sender has full control over who receives and can access the files (through authentication of users) and for which period of time – as it should be. With privacy, data security and digital sovereignty high on the agenda of both organizations and individuals, the FileSender open source web application provides a secure, trustworthy and transparent way for sharing large files.
Global FileSender initiative to improve file transfer efficiency
FileSender is widely adopted worldwide by many NRENs to offer national-level file-transferring services. Through GakuNin, the Japanese Academic Access Management Federation, 408 R&E organisations in Japan can access the FileSender service. However, there are some issues with international file sharing:
- The farther the FileSender server is from the user, the longer it takes to upload/download files;
- When sharing large files, users in remote locations must wait long periods for the files to transfer.
There are many FileSender servers around the world. Creating a global network of interconnected FileSender installations would improve the speed of international file sharing over long distances, showing how FileSender servers around the world can work together to transfer files at high speed from the sender’s FileSender server to a FileSender server close to the receiver. In that case, the receiver can quickly download the file from the destination.
Global FileSender was developed with the file forwarding feature added to the source code in FileSender Release 3.0, contributed by NII – a function that asynchronously and quickly forwards uploaded files to another FileSender site. The user can instruct forwarding to another server using the Transfer setting (forward_to_another_server and forward_server_name). The receiver will get a download notification email from the server at the destination. The file transfer tool used is MMCFTP (Massively Multi-Connection File Transfer Protocol), developed by NII, but other methods (SCP, REST API) can also be used. This function is implemented as an optional feature of FileSender, and unless explicitly configured, it works no differently from the regular FileSender.
NII started a trial service of Global FileSender on October 31, 2025. Several community updates were made for this function. This extension has been fully merged into FileSender 3.x, and the Global FileSender trial service is currently using the latest version, FileSender 3.10 (released on June 9, 2026).
NII provides three servers for the trial. These are placed:
- gfs-kitami-jp.sinet.ad.jp in Hokkaido (Japan),
- gfs-amsterdam-nl.sinet.ad.jp in Amsterdam (the Netherlands),
- gfs-newyork-us.sinet.ad.jp in New York (USA).
International cooperation in cutting-edge technology fields often requires sharing very large amounts of data. For frequent transfers, it would be possible to build a dedicated system or use a paid service. However, infrequent or sporadic data sharing typically means accepting slower transfer speeds. This service aims to support such use cases.
The service is useful for sharing large files (1 GB – several hundred GB) between Japan and Europe, as well as between Japan and the United States. Data transfer speed between the three servers is 10 Gbps. Global FileSender, currently a trial service, is scheduled to become a formal service in 2028.
At present, the Global FileSender trial service is available not only to users of GakuNin, but also to users of IdPs participating in eduGAIN from 28 countries (in Europe, Asia, Oceania, North and South America). With so many countries participating in eduGAIN, it is not possible to support all of them – that’s why the export control restrictions should be considered.
The final goal of this initiative is for FileSender servers worldwide – mainly those provided by NRENs – to work together to support a single file-transferring service. There are various requirements (such as network bandwidth, storage performance, etc.), and coordination of the service level is necessary.
The first limitation of implementing Global FileSender is connected with the need to improve the FileSender downloading speed of the encrypted files. NII planned to make the FileSender encryption function mandatory in the server-to-server transfer mode, because MMCFTP lacks this feature. However, encryption significantly reduces transfer speed when downloading a file. For this reason, NII chose not to mandate encryption for the Global FileSender trial service. Instead, an L2VPN (VPLS) is used to connect servers, ensuring secure transfers even without encryption.
The second issue is related to the fact that some FileSender functions conflict with the server-to-server file transfer operation – and are disabled in the server-to-server file transfer mode. For example,
- “Transfer link” function: the link is determined only after the file is transferred to the other server;
- Advanced option “User must login to FileSender to download file(s)”: there is no guarantee that the user will be able to login to the destination server.
Strengthening the FileSender community: NII’s support
NII started supporting FileSender development financially by signing the Bronze-level contribution agreement on November 6, 2025.
“NII has been providing a domestic file-transferring service using FileSender since 2017, and more contribution to the FileSender community has been a long-standing issue. Global FileSender requires collaboration with FileSender services across various countries – therefore, closer collaboration with the FileSender community is necessary. Taking this opportunity, we have decided to begin financial support”.
We are grateful to NII for sharing the open source software solutions and open source values, and assisting with this funding to the FileSender project joint efforts. This commitment is very encouraging for the FileSender long-term sustainability. If you think the FileSender software is valuable and you want to support its continued development financially or in-kind, please let us know by sending an email directly to the FileSender Board.
While challenges remain, the Global FileSender trial service marks an important first step. The next big step would be for other NRENs to join this initiative. NII will offer MMCFTP to participating NRENs, with availability and terms to be announced soon. Connecting FileSender installations across countries will enable a more convenient file-transferring service for users worldwide.
We would appreciate feedback from the FileSender community. You can share your thoughts and suggestions about the Global FileSender initiative by sending an email directly to the FileSender Board.
Please see Support and Mailing lists to stay updated on the latest FileSender developments and important news.
Credits: deployment map created by MapChart, database icons created by phatplus – Flaticon.