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About
croc is a tool that allows any two computers to simply and securely transfer files and folders. AFAIK, croc is the only CLI file-transfer tool that does all of the following:
Allows any two computers to transfer data (using a relay)
Provides end-to-end encryption (using PAKE)
Enables easy cross-platform transfers (Windows, Linux, Mac)
Allows multiple file transfers
Allows resuming transfers that are interrupted
No need for local server or port-forwarding
IPv6-first with IPv4 fallback
Can use a proxy, like Tor
For more information about croc, see my blog post or read a recent interview I did.
Install
You can download the latest release for your system, or install a release from the command-line:
the latest release for your system
On macOS
Using Homebrew:
Using MacPorts:
On Windows
You can install the latest release with Scoop, Chocolatey, or Winget:
Using nix-env
You can install the latest release with Nix:
On NixOS
You can add this to your configuration.nix:
On Alpine Linux
First, install dependencies:
On Arch Linux
Install with pacman:
On Fedora
Install with dnf:
On Gentoo
Install with portage:
On Termux
Install with pkg:
On FreeBSD
Install with pkg:
On Linux, macOS, and Windows via Conda
You can install from conda-forge globally with pixi:
Or install into a particular environment with conda:
On Linux, macOS via Docker
Add the following one-liner function to your ~/.profile (works with any POSIX-compliant shell):
You can also just paste it in the terminal for current session. On first run Docker will pull the image. croc via Docker will only work within the current directory and its subdirectories.
Build from Source
If you prefer, you can install Go and build from source (requires Go 1.22+):
On Android
There is a 3rd-party F-Droid app available to download.
Usage
To send a file, simply do:
Then, to receive the file (or folder) on another computer, run:
The code phrase is used to establish password-authenticated key agreement (PAKE) which generates a secret key for the sender and recipient to use for end-to-end encryption.
Customizations & Options
Using croc on Linux or macOS
On Linux and macOS, the sending and receiving process is slightly different to avoid leaking the secret via the process name. You will need to run croc with the secret as an environment variable. For example, to receive with the secret ***:
leaking the secret via the process name
For single-user systems, the default behavior can be permanently enabled by running:
Custom Code Phrase
You can send with your own code phrase (must be at least 6 characters):
Allow Overwriting Without Prompt
To automatically overwrite files without prompting, use the --overwrite flag:
Excluding Folders
To exclude folders from being sent, use the --exclude flag with comma-delimited exclusions:
Use Pipes - stdin and stdout
You can pipe to croc:
To receive the file to stdout, you can use:
Send Text
To send URLs or short text, use:
Send Multiple Files
You can send multiple files directly by listing the files and/or folders:
Show QR Code
To show QR code (for mobile devices), use:
Use a Proxy
You can send files via a proxy by adding --socks5:
Change Encryption Curve
To choose a different elliptic curve for encryption, use the --curve flag:
Change Hash Algorithm
For faster hashing, use the imohash algorithm:
Clipboard Options
By default, the code phrase is copied to your clipboard. To disable this:
To copy the full command with the secret as an environment variable (useful on Linux/macOS):
This copies the full command like CROC_SECRET="code-phrase" croc (including any relay/pass flags).
Quiet Mode
To suppress all output (useful for scripts and automation):
Self-host Relay
You can run your own relay:
By default, it uses TCP ports 9009-9013. You can customize the ports (e.g., croc relay --ports 1111,1112), but at least 2 ports are required.
To send files using your relay:
Self-host Relay with Docker
You can also run a relay with Docker:
To send files using your custom relay:
To use custom ports, set CROC_PORTS (comma-separated) or CROC_PORT (base port):
Acknowledgements
croc has evolved through many iterations, and I am thankful for the contributions! Special thanks to:
@warner for the idea
@tscholl2 for the encryption gists
@skorokithakis for proxying two connections
And many more!