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signal-cli is a commandline interface for libsignal-service-java. It supports registering, verifying, sending and receiving messages. To be able to link to an existing Signal-Android/signal-cli instance, signal-cli uses a patched libsignal-service-java, because libsignal-service-java does not yet support provisioning as a linked device. For registering you need a phone number where you can receive SMS or incoming calls. signal-cli is primarily intended to be used on servers to notify admins of important events. For this use-case, it has a dbus interface (man page), that can be used to send messages from any programming language that has dbus bindings. It also has a JSON-RPC based interface, see the documentation for more information.


You can build signal-cli yourself, or use the provided binary files, which should work on Linux, macOS and Windows. For Arch Linux there is also a package in AUR and there is a FreeBSD port available as well.

System requirements:

  • at least Java Runtime Environment (JRE) 11

  • native libraries: libzkgroup, libsignal-client

    Those are bundled for x86_64 Linux (with recent enough glibc, see #643), for other systems/architectures see: Provide native lib for libsignal

Install system-wide on Linux

See latest version.

export VERSION=<latest version, format "x.y.z">
sudo tar xf signal-cli-"${VERSION}".tar.gz -C /opt
sudo ln -sf /opt/signal-cli-"${VERSION}"/bin/signal-cli /usr/local/bin/

You can find further instructions on the Wiki:


For a complete usage overview please read the man page and the wiki.

Important: The USERNAME is your phone number in international format and must include the country calling code. Hence it should start with a "+" sign. (See Wikipedia for a list of all country codes.)

  • Register a number (with SMS verification)

      signal-cli -u USERNAME register

    You can register Signal using a land line number. In this case you can skip SMS verification process and jump directly to the voice call verification by adding the --voice switch at the end of above register command.

    Registering may require solving a CAPTCHA challenge: Registration with captcha

  • Verify the number using the code received via SMS or voice, optionally add --pin PIN_CODE if you've added a pin code to your account

      signal-cli -u USERNAME verify CODE
  • Send a message

      signal-cli -u USERNAME send -m "This is a message" RECIPIENT
  • Pipe the message content from another process.

      uname -a | signal-cli -u USERNAME send RECIPIENT
  • Receive messages

      signal-cli -u USERNAME receive

Hint: The Signal protocol expects that incoming messages are regularly received (using daemon or receive command). This is required for the encryption to work efficiently and for getting updates to groups, expiration timer and other features.


The password and cryptographic keys are created when registering and stored in the current users home directory:



This project uses Gradle for building and maintaining dependencies. If you have a recent gradle version installed, you can replace ./gradlew with gradle in the following steps.

  1. Checkout the source somewhere on your filesystem with

     git clone
  2. Execute Gradle:

     ./gradlew build

    3a. Create shell wrapper in build/install/signal-cli/bin:

     ./gradlew installDist

    3b. Create tar file in build/distributions:

     ./gradlew distTar

    3c. Compile and run signal-cli:

     ./gradlew run --args="--help"

Building a native binary with GraalVM (EXPERIMENTAL)

It is possible to build a native binary with GraalVM. This is still experimental and will not work in all situations.

  1. Install GraalVM and setup the enviroment

  2. Install prerequisites

  3. Execute Gradle:

     ./gradlew nativeCompile

    The binary is available at build/native/nativeCompile/signal-cli

FAQ and Troubleshooting

For frequently asked questions and issues have a look at the wiki


This project uses libsignal-service-java from Open Whisper Systems:

Licensed under the GPLv3:

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