PrivyDrop's New Milestone: Resumable Transfers to End Large File Transfer Anxiety

Introduction: The Final Mile from "Usable" to "Enjoyable"

In previous articles, we introduced the open-source spirit of PrivyDrop and the core technology behind it, WebRTC. We successfully created a secure and private file-sharing tool based on peer-to-peer (P2P) technology.

However, we know that a tool's value lies not just in being "usable," but in how "enjoyable" it is in the real world. Imagine this scenario: you're at a coffee shop with unstable Wi-Fi, sending an urgent 4GB rendered video file to a client. The progress bar slowly creeps to 95%, and then... the network drops.

We've all felt that gut-wrenching frustration of failure at the last moment.

Today, we are proud to announce that PrivyDrop has completed that final mile from "usable" to "enjoyable." We are officially launching the resumable transfers feature, designed to put an end to your "transfer anxiety" for good.

The Core Weapon: How Do Smart Resumable Transfers Work?

Before diving into how to use it, you might be wondering: how does PrivyDrop "remember" the transfer progress?

Unveiling the Principle: How is the "Memory" of Resumable Transfers Achieved?

We like to compare the process to assembling a giant digital jigsaw puzzle:

Exchanging the "Blueprint": Before the transfer begins, the sender first sends a "blueprint" of the file (i.e., metadata containing the filename, total size, chunk information, etc.) to the receiver. The receiver uses this blueprint to get a complete picture of the "puzzle" ahead of time.
Receiving "Puzzle Pieces" by Number: The file is divided into countless small data chunks, which are numbered and transferred sequentially. As the receiver gets each piece, they place it in its correct position on the "blueprint."
The "Smart Inventory" After an Interruption: When the transfer is unexpectedly interrupted, the receiver holds onto all the "puzzle pieces" they've already collected. When the connection is re-established, the receiver takes out the "blueprint," does an inventory check, and tells the sender: "I already have pieces #1 to #5000. Please start sending from #5001."

This "smart inventory and request" mechanism is the core of our resumable transfer technology. It eliminates the need to start from scratch, dramatically improving the efficiency and reliability of large file transfers.

A Practical Guide: How to Use Resumable Transfers Correctly

Now, let's walk through how to master this powerful feature in practice.

Step 1: Enable "Safe Mode" (Receiver)

Before receiving a file, you must click "Set Save Directory". This step is crucial. It tells PrivyDrop, "Please prepare a safe home for the incoming file." Only then will the resumable transfer feature be activated.

Step 2: When an Interruption Occurs

Network fluctuations, accidentally closing the tab, your computer going to sleep... when interruptions inevitably happen, stay calm. Your file progress is safe.

Step 3: Lock in Your Progress (The Key Action)

To lock in and securely save the file fragments you've already received, you need to refresh or close the current page.

This is where PrivyDrop's carefully designed Exit Protection Mechanism comes into play. Normally, if a page with an active download is suddenly closed, the browser might discard the incomplete temporary file, leading to data loss.

We've engineered a solution: when you refresh or close the page, PrivyDrop's code intercepts this action. Instead of letting the browser abandon the file, it acts like a responsible archivist, gracefully closing the disk write stream to finalize and save the data already received. This action transforms the temporary file into a stable "save point" ready for the next transfer attempt.

Step 4: Seamless Resumption

Now, simply have the sender and you re-enter the same room and start the transfer again. You'll magically see the progress bar jump to where it left off and continue its steady march forward. That's the magic of resumable transfers!

From "Single Task" to "Continuous Collaboration": Meet Your Private Data Channel

Having solved the reliability of large file transfers, we also wanted to make the exchange process more intuitive. Traditional tools operate on a "send one, start over" model. PrivyDrop, however, provides a persistent private data channel.

Once two parties are connected, the room becomes your exclusive "virtual office." You can share content continuously without repeating the "create room, share link" cycle every time.

Imagine this workflow:

You send a text description via the clipboard.
After the other person receives it, you drag and drop a design mockup (a PNG file).
Once the mockup is sent, you immediately follow up by dragging in a folder containing all the assets.

The entire process is fluid and natural, just like talking to a colleague sitting next to you. This "continuous transfer" feature elevates PrivyDrop from a "one-time file transfer tool" to a "lightweight, highly private, real-time collaboration space."

When "Reliability" Meets "Privacy"

You might be wondering if these powerful new features come at the cost of PrivyDrop's privacy.

The answer is: absolutely not. All our feature development is built on a foundation of privacy and security.

Resumable Transfers & End-to-End Encryption: We want to be clear: even the fragmented file chunks used for resumable transfers are transmitted with the same end-to-end encryption (DTLS protocol) as a complete file, directly between browsers. The server can never inspect, reassemble, or store any of the content.
"Unlimited Size" x "Resumable Transfers": This is our proud "golden combination." "No file size limits" is our promise, and "resumable transfers" is the insurance that lets us keep it. Now you can truly use PrivyDrop to back up an entire hard drive or transfer massive datasets without fear of losing your progress.
The Confidence of Open Source: We don't just promise security; we show our work. Every line of code for our resumable and continuous transfer features is publicly available in our GitHub repository, open for review and scrutiny by developers worldwide.

Conclusion: We Invite You to a "Fearless" Transfer

PrivyDrop is no longer just a tool; it's becoming the trustworthy partner you can rely on for your personal and professional data, fearless of any interruption.

Don't hesitate! Visit privydrop.app right now, find the largest file on your computer, and intentionally refresh the page mid-transfer. Experience for yourself that reassuring feeling of "recovering the lost."

If you're as passionate as we are about building ultra-secure and reliable tools, please give us a Star on GitHub. Your support is our greatest motivation!