diff --git a/pyproject.toml b/pyproject.toml
index b97ae58e4de..4f33eff8b15 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ dependencies = [
 
 [project.optional-dependencies]
 accel = ["scipy", "bottleneck", "numbagg", "flox", "opt_einsum"]
-complete = ["xarray[accel,io,parallel,viz,dev]"]
+complete = ["xarray[accel,etc,io,parallel,viz]"]
 dev = [
   "hypothesis",
   "mypy",
@@ -40,11 +40,14 @@ dev = [
   "pytest-xdist",
   "pytest-timeout",
   "ruff",
+  "sphinx",
+  "sphinx_autosummary_accessors",
   "xarray[complete]",
 ]
 io = ["netCDF4", "h5netcdf", "scipy", 'pydap; python_version<"3.10"', "zarr<3", "fsspec", "cftime", "pooch"]
+etc = ["sparse"]
 parallel = ["dask[complete]"]
-viz = ["matplotlib", "seaborn", "nc-time-axis"]
+viz = ["cartopy", "matplotlib", "nc-time-axis", "seaborn"]
 
 [project.urls]
 Documentation = "https://docs.xarray.dev"