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1. Don't lock the db so carelessly
2. Deal better with favorites not being there
3. Show some countdown stats (Closes #4826 although the UI needs doing)

Addresses #4825 also

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Surge XT

If you are a musician looking to use Surge, please download the appropriate binary from our website. Surge Synth Team makes regular releases for all supported platforms.

If you are a developer looking to compile a stable production version of Surge, please do not use the main branch; instead, use a release tag (such as release_1.9.0) or branch (such as release/1.9.0). Surge is undergoing substantial development right now, and the main branch is currently an incomplete alpha version for our Fall 2021 release.

CI: CI Build Status Release: Release Build Status Release-XT: Release-XT Build Status

Surge is a free and open-source hybrid synthesizer, originally written and sold as a commercial product by @kurasu/Claes Johanson at Vember Audio. In September 2018, Claes decided to release a partially completed version of Surge 1.6 under GPL3, and a group of developers have been improving it since. You can learn more about the team at or connect with us on Discord.

If you would also like to participate in discussions, testing and design of Surge, we have details below and also in the contributors section of the Surge website.

In Spring 2021, after the release of Surge 1.9, Surge Synth Team embarked on a plan to replatform Surge as a JUCE plugin. There are a variety of reasons for this choice, including the difficulty of maintaining hand-rolled wrappers around VST3, AU and LV2 and limitations in the VSTGUI framework.

As such, if you are looking to build Surge in the 1.9 family, you need to use the GitHub branch classic (for the head of the code; although it has no diffs since 1.9 of note) or the tag release_1.9.0 to build exactly the 1.9 release.

This readme serves as the root of developer documentation for Surge.

Developing Surge XT

We welcome developers! Our workflow revolves around GitHub issues in this repository and conversations at our Discord server and IRC chatroom. You can read our developer guidelines in our developer guide document. If you want to contribute and are new to Git, we also have a Git How To, tailored at Surge development.

The developer guide also contains information about testing and debugging in particular hosts on particular platforms.

Surge XT uses CMake for all of its build-related tasks, and requires a set of free tools to build the synth. If you have a development environment set up, you almost definitely have what you need, but if not, please check out:

Once you have set your environment up, you need to checkout the Surge code with Git, grab submodules, run CMake to configure, then run CMake to build. Your IDE may support CMake (more on that below), but a reliable way to build Surge on all platforms is:

git clone
cd surge
git submodule update --init --recursive
cmake -Bbuild
cmake --build build --config Release --target surge-staged-assets

This will build all the Surge binary assets in the directory build/surge_xt_products and is often enough of a formula to do a build.

Developing from your own fork

Our Git How To explains how we are using Git. If you want to develop from your own fork, please consult there, but the short version is (1) fork this project on GitHub and (2) clone your fork, rather than the main repo as described above. So press the Fork button here and then:

git clone

and the rest of the steps are unchanged.

Building projects for your IDE

When you run the first CMake step, CMake will generate IDE-compatible files for you. On Windows, it will generate Visual Studio files. On Mac it will generate makefiles by default, but if you add the argument -GXcode you can get an XCode project if you want.

Surge developers regularly develop with all sorts of tools. CLion, Visual Studio, vim, emacs, VS Code, and many others can work properly with the software.

Building a VST2

Due to licensing restrictions, VST2 builds of Surge may not be re-distributed. However, it is possible to build a VST2 of Surge for your own personal use. First, obtain a local copy of the VST2 SDK, and unzip it to a folder of your choice. Then set VST2SDK_DIR to point to that folder:

export VST2SDK_DIR="/your/path/to/VST2SDK"

or, in the Windows command prompt:

set VST2SDK_DIR=c:\path\to\VST2SDK

Finally, run a fresh CMake, and build the VST2 targets:

cmake -Bbuild_vst2
cmake --build build_vst2 --config Release --target surge-xt_VST --parallel 4
cmake --build build_vst2 --config Release --target surge-fx_VST --parallel 4

You will then have VST2 plugins in build_vst2/surge-xt_artefacts/Release/VST and build_vst2/surge-fx_artefacts/Release/VST respectively. Adjust the number of cores that will be used for building process by modifying the value of --parallel argument.

Building with support for ASIO

On Windows, building with ASIO is often preferred for Surge standalone, since it enables users to use the ASIO low-latency audio driver.

Unfortunately, due to licensing conflicts, binaries of Surge that are built with ASIO may not be re-distributed. However, you can build Surge with ASIO for your own personal use, provided you do not re-distribute those builds.

If you already have a copy of the ASIO SDK, simply set the following environment variable:

set ASIOSDK_DIR=c:\path\to\asio

If you do not have a copy of the ASIO SDK, CMake can download it for you, and allow you to build with ASIO under your own personal license. To enable this functionality, run your CMake configuration command as follows:


Building an LV2

On Linux, using a community fork of JUCE, you can build an LV2. Here's how. We assume you have checked out Surge and can build.

First, clone on branch lv2, to some directory of your chosing.

sudo apt-get install -y lv2-dev
cd /some/location
git clone --branch lv2 JUCE-lv2

then run a fresh CMake to (1) point to that JUCE fork and (2) activate LV2

cmake -Bbuild_lv2 -DCMAKE_BUILD_TYPE=Release -DJUCE_SUPPORTS_LV2=True -DSURGE_JUCE_PATH=/some/location/JUCE-lv2/
cmake --build build_lv2 --config Release --target surge-xt_LV2 --parallel 4
cmake --build build_lv2 --config Release --target surge-fx_LV2 --parallel 4

You will then have LV2s in build_lv2/surge-xt_artefacts/Release/LV2 and build_lv2/surge-fx_artefacts/Release/LV2 respectively.

Building an Installer

The CMake target surge-xt-distribution builds an install image on your platform at the end of the build process. On Mac and Linux, the installer generator is built into the platform; on Windows, our CMake file uses NuGet to download InnoSetup, so you will need the nuget.exe CLI in your path.

Using CMake on the Command Line for More

In Surge 1.6-1.9 we had a pair of scripts and which originated before Surge was a cmake project and contained a lot of utility functions. We have moved those to cmake and as a result, have a bunch of features our CMake file supports which make development easier on the command lines and in CMake aware IDEs.

Plugin Development

JUCE supports a mode where a plugin (AU, VST3, etc...) is copied to a local install area after a build. This is off by default with CMake JUCE but you can turn it on with -DSURGE_COPY_AFTER_BUILD=True at cmake time. If you do this on unixes, building the VST3 or AU targets will copy them to the appropriate local area (~/.vst3 on linux, '~/Library/Audio/Plugins` on mac). On windows it will attempt to install the VST3 so setting this option may require admin privileges in your build environment.

CMake Install Targets (Linux and other non-apple unixes only)

On systems which are UNIX AND NOT APPLE, the cmake file provides an install target which will install all needed assets to the CMAKE_INSTALL_PREFIX. This means a complete install can be accomplished by

cmake -Bignore/sxt -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
cmake --build ignore/sxt --config Release --parallel 8
sudo cmake --install ignore/sxt

and you should get a working install in /usr/bin, /usr/share and /usr/lib

Installing assets (unixes only)

The targets install-resources-local and install-resources-global install the plugin resources to the appropriate surge-xt or Surge XT directories on your system in the unixes. The global option will require elevated priviledges.

Running the standalone from cmake directly

For @baconpaul, at least, it is useful to have a cmake command that builds stuff and runs the standalone. The target surge-xt-run-standalone does this. Here's a sample cmake session (using the surge ignore directory which we keep in our .gitignore file):

cmake -Bignore/lind -DCMAKE_BUILD_TYPE=Debug
cmake --build ignore/lind/ --config Debug --target install-resources-local
cmake --build ignore/lind/ --config Debug --target surge-xt-run-standalone --parallel 4

The second line is only needed if you've never installed resources, obviously.

Platform Specific Choices

Building 32- vs 64-bit on Windows

If you are building with Visual Studio 2019, then use the -A flag in your CMake command to specify 32/64-bit:

# 64-bit
cmake -Bbuild -G"Visual Studio 16 2019" -A x64

# 32-bit
cmake -Bbuild -G"Visual Studio 16 2019" -A Win32

If you are using an older version of Visual Studio, you must specify your preference with your choice of CMake generator:

# 64-bit
cmake -Bbuild -G"Visual Studio 15 2017 Win64"

# 32-bit
cmake -Bbuild -G"Visual Studio 15 2017"

Building a Mac Fat Binary (ARM/Intel)

To build a fat binary on a mac, simply add the following CMAKE argument to your intiial cmake run.


Building for Raspberry Pi

To build for a Raspberry Pi, you want to add the LINUX_ON_ARM CMake variable when you first run CMake. Otherwise, the commands are unchanged. So, on a Pi, you can do:

cmake -Bbuild -DLINUX_ON_ARM=True
cmake --build build --config Release --target surge-staged-assets

Cross Compiling for aarch64

To cross compile for aarch64 us the cmake linux toolchain for aarch4, as shown in the azure pipeline here.

cmake -Bignore/xc64 -DCMAKE_TOOLCHAIN_FILE=cmake/linux-aarch64-ubuntu-crosscompile-toolchain.cmake -DCMAKE_BUILD_TYPE=DEBUG -GNinja
cmake --build ignore/xc64 --config Debug --target surge-headless

Of course that toolchain makes specific choices. You can make other choices as long as (1) you set the CMAKE variable LINUX_ON_ARM and (2) you make sure your host and your target compiler are both 64 bit.

Setting up for Your OS


You need to install the following:


To build on macOS, you need Xcode, Xcode Command Line Utilities, and CMake. Once you have installed Xcode from the App Store, the command line to install the Xcode Command Line Utilities is:

xcode-select --install

There are a variety of ways to install CMake. If you use homebrew you can:

brew install cmake


Most Linux systems have CMake, Git and a modern C++ compiler installed. Make sure yours does. We test with most gccs older than 7 or so and clangs after 9 or 10. You will also need to install a set of dependencies. If you use apt do:

sudo apt install build-essential libcairo-dev libxkbcommon-x11-dev libxkbcommon-dev libxcb-cursor-dev libxcb-keysyms1-dev libxcb-util-dev libxrandr-dev libxinerama-dev libxcursor-dev libasound2-dev libjack-dev

Continuous Integration

In addition to the build commands above, we use Azure pipelines for continuous integration. This means that each and every pull request will be automatically built on all our environments, and a clean build on all platforms is an obvious pre-requisite. If you have questions about our CI tools, don't hesitate to ask on our Discord server. We are grateful to Microsoft for providing Azure pipelines for free to the open-source community!