copyparty: Your Files, Your Rules

On Sunday evening, I installed copyparty on the PC in my studio, just to see what it could do. On Monday, my girlfriend asked for the videos from our outing. Three gigabytes: the sort of attachment that makes a messaging app quietly reconsider its career.

I sent her a copyparty link from my phone. She downloaded the videos in two minutes, without creating an account. That was my transfer on that occasion, not a speed promise. But the useful part was wonderfully ordinary: she wanted the files, she opened a link, she got the files.

Naturally, I immediately decided to share a few more folders. Then a few too many. A small success can do terrible things to your sense of restraint.

A file server without the ceremony

copyparty is free, MIT-licensed, open-source software that turns a computer into a file server. Visitors use a browser to browse the folders you expose, download files, and upload things if you allow it. The server runs on your machine; the person receiving the link does not need a matching desktop application.

That makes it appealing for a specific, slightly neglected job: handing somebody files without first placing them in a third-party cloud account. A spare computer can become a shared shelf. A project folder can become a delivery point. Your phone can visit that shelf like any other browser-equipped device.

There is more underneath than the modest premise suggests. The official documentation lists resumable uploads, per-user and per-folder permissions, WebDAV, and optional media indexing and thumbnails. Some extras need additional components. You do not have to turn them all on. A server that simply serves the right folder is already doing useful work.

The day the link stopped working

Three days later, my girlfriend messaged: "The link doesn't work anymore."

I had switched off the PC before leaving for work. That was the entire mystery. No dramatic outage, no lost account: the machine serving the files was no longer running. My personal cloud had left the building with me, emotionally if not physically.

That is the trade-off worth understanding before getting carried away. Self-hosting gives you control, but it also gives you the job of keeping the host available. Power, sleep settings, the running server, and the network connection all matter. A link is an address, not a promise that someone will be home.

I kept copyparty, but for large, occasional transfers rather than sharing everything indefinitely. "It works at home" and "it works all the time" turned out to be two different statements.

Start with one harmless folder

The official quickstart offers a self-contained Python launcher, alongside package-manager and other installation options. Windows, macOS, and Linux users have documented routes. For a first look, use a dedicated folder containing throwaway files, not your home directory and its miscellaneous archaeological layers.

There is an important warning in the README: starting copyparty without arguments grants everyone read/write access to the current folder. Do not skim past that sentence. Configure the volumes and permissions deliberately, and grant only the access you actually want. A read-only handoff and a shared upload folder are different jobs.

Network access also needs thought. A link that works on your own network is not automatically reachable elsewhere. Remote access requires an appropriate network setup and security choices. My story does not establish which route another reader should use, and exposing a port is not a substitute for understanding it.

Our separate basic check used a dedicated folder and a server bound only to the local loopback address. Reading a sample text file returned HTTP 200. Uploading another through WebDAV PUT returned 201, and reading it back produced identical bytes. That verifies a small part of the plumbing, not browser usability, interrupted-transfer recovery, internet performance, or a complete security review.

A useful tool with a very clear job

copyparty makes sense when you want a browser-accessible place to hand over files and are comfortable managing the machine behind it. It is less attractive if you need unattended, always-available sharing but do not want to think about uptime or permissions.

For me, the sweet spot is now clear: start it for a transfer, share only what is needed, keep the PC awake, and stop treating one successful link as permission to expose the entire cupboard. The videos arrive. Nobody creates another account. And the computer stays on until the job is finished.

Official documentation and source code: https://github.com/9001/copyparty

Cover image: official copyparty project screenshot, showing the browser and audio player.