The curious thing about BitTorrent Sync, a service that lets users share files in a peer-to-peer fashion rather than via the cloud, is that security-conscious users make up a significant portion of its audience. Since BitTorrent is probably best known as a technology used by illegal file sharers, it has a reputation, at least among companies with intellectual property, as a mechanism for leaking their valuable content.

And yet, since it opened up to all users in April last year, BitTorrent Sync has signed up 10 million registered users. Given the nature of the service, it's likely that a decent portion of its customers are using it for work. Either those users are doing so without permission of their employer, or BitTorrent has managed to gain their trust by showing the value of the offering.  

BitTorrent is today rolling out BitTorrent Sync 1.4, designed to make it easier to use for -- yes -- sharing content.

The service was initially developed as part of an internal hackathon at BitTorrent, said Erik Pounds, vice president of product management at the company. "It was built by engineers, for engineers," he said. "The use case was syncing folders on their devices that they own. As the product was released to the market through the alpha and into the initial beta, it was obvious that people were using this product to interact with other people. That wasn't the initial design of the product."

Since Sync was first launched, BitTorrent has invested in making it a fully functioning product by dedicating developer resources as well as adding product managers so that it could identify target audiences and design around their use cases, he said. "With Sync 1.4, you're seeing the first fruits of that."

One target audience is people who use very large files that they either want to share with others or access from multiple devices. "The public cloud is not great at data transfer because you have to upload and then bring it back down," he said. "If it's device to device, whether you're behind a firewall or on a local LAN or on cellular, it will get there faster."

Since BitTorrent began offering Sync, it has supported over 80 petabytes of data transfer, Pounds said. For comparison, 10 billion photos on Facebook equals just over 1 petabyte.

Another set of target customers are very security-conscious users. "With BitTorrent, no other entity knows who you are or what you're doing," Pounds said. That's because files are shared peer-to-peer, without stopping to be stored on servers controlled by BitTorrent or anyone else. If files have to travel over the Internet, the payload is encrypted, he said.

The updates in version 1.4 really focus on this content sharing use case. In the past, users had to work through a complicated process to let other people view a shared folder. Now, users can send a link to people they want to share content with. Sync 1.4 also generates a QR Code linking to content, which some people might find easy for sharing content with mobile phone users.

When users share content with other people, the recipient doesn't have to have an account with BitTorrent to receive the content. Sync already had a key feature that requires a recipient to read a key, received with the file, back to the sender before being able to open the file, for an extra level of security.

Users get new controls too so that they can set documents as read-only or allow for editing. They can control links too, setting them to work for a certain period of time or to expire after a specified number of uses or to allow anyone to access the link anytime.

Sync 1.4 also offers users a new interface that lets them view which devices are connected to a given folder and whether devices or users are out of sync. User can also view sync progress, including which sources are syncing data in each folder.

BitTorrent has featured a number of case studies on its blog about users of Sync, indicating that there are plenty of business users. It points to a wedding photographer who uses Sync to collaborate with other photographers, a cancer researcher who uses it to work with global colleagues, and a design agency in Norway that uses Sync to share files across offices in three different countries.

One catch is that, especially for people who are attracted to BitTorrent Sync for capabilities around very large files, is it's not certain what it will cost. For now, it's free. "Our goal is always to have a very good free version. At a certain level we'll monetize," Pounds said.

Regardless of what BitTorrent ultimately charges for the service, users may also need to buy their own storage, if the storage built into their devices isn't sufficient to support the content they want to store and share. BitTorrent has made Sync available on network-attached storage gear from Seagate, NETGEAR, Synology, Overland Storage, and QNAP.

SyncboxTonido,PocketCloud, and GetMeMyFiles are other companies offering sync services without the cloud.