Questions people ask first
The ones worth answering before you download rather than after.
Why does it need administrator rights?
Because packets are intercepted by a kernel driver, and Windows does not load one for a normal user. The program asks for the rights itself when it starts. From the command line it refuses with a specific exit code instead of failing halfway through.
Will it break the whole machine or just my app?
Whatever you point it at. Set a target and only that application is affected. Leave the target empty and every connection on the computer is - which the program warns you about, in the window and on the command line, before you can wonder why the video call dropped.
How do I undo it?
STOP. Closing the program does the same, and so does a time limit if you set one. If the tool itself dies mid-session, a watchdog inside it shuts the capture down rather than leaving your network impaired - a session must never outlive the program that started it.
Does it send anything anywhere?
No. There is no analytics, no crash reporting to a service and no update check. The program has no network client at all. The only outgoing connection it can make is opening the support page in your browser, after you click it. It intercepts your traffic, so that traffic must never leave your machine, and this page you are reading loads nothing from anyone else either.
Windows warned me about the download. Why?
Because the executable is new and unsigned, and SmartScreen flags anything it has not seen before. A code-signing certificate is a yearly cost, not a statement about the file. Every release publishes a SHA-256 checksum, a list of components, and a signature tying the two to the build that produced them, so you can verify what you downloaded instead of trusting a green tick.
My download died completely and nothing says why
Check the maximum packet size. Set low enough, it is not a smaller packet, it is a black hole: the network drops what is too big and never reports it. Set it back and the transfer returns.
Does it work on Linux or macOS?
No, and it will not. It stands on a Windows kernel driver. On Linux, tc with
netem does this job and is already installed.
Is it really free? Can I use it at work?
Yes. It is free and open source under the GNU GPL v3, including at work, with the source available for anyone to read or change. The download is the same file for everybody.