DecSync for Evolution is an Evolution plugin which synchronizes contacts and calendars using DecSync. To start synchronizing, all you have to do is synchronize the DecSync directory (by default ~/.local/share/decsync), using for example Syncthing.

For Debian/Ubuntu, there is a .deb package available at the releases page.

For Arch Linux, there is a AUR package available, created by vasket.

In addition to the dependencies below, the library libdecsync is also required.

Install dependencies:

sudo apt install \
	build-essential \
	git \
	meson \
	ninja-build \
	pkg-config \
	libjson-glib-dev \
	libebook1.2-dev \
	libedata-book1.2-dev \
	libedata-cal2.0-dev \
	evolution-dev

sudo dnf install \
	cmake \
	git \
	gcc \
	meson \
	json-glib-devel \
	evolution-data-server-devel \
	evolution-devel

sudo pacman -S \
	cmake \
	meson \
	ninja \
	json-glib \
	evolution-data-server \
	evolution

git clone --recursive https://github.com/39aldo39/Evolution-DecSync
cd ./Evolution-DecSync
meson build
sudo ninja -C build install

Note: the master branch does not work for older versions of Evolution. For those, use the evolution-3.40 branch, or similar, instead.

Once building is complete, enable syncing with Evolution by:

1. Restart your computer
2. Open Evolution
3. Click Edit → Accounts
4. In the window that opens, you can use Add on the right-hand side to add an Address Book or Calendar.
5. For type, select DecSync; eventually check Mark as default address book/calendar. If applicable, select the location of your DecSync folder.
6. A new address book will appear. Right-click it and select Refresh to instantly show your contacts/events.

All done!