diff --git a/tox.ini b/tox.ini
index 12c11f50..c27673b6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,43 +1,81 @@
 [tox]
 envlist=flake8,mypy,py3-django2
 
 [testenv]
 extras =
   testing
 deps =
   # the dependency below is needed for now as a workaround for
   #   https://github.com/pypa/pip/issues/6239
   swh.core[http] >= 0.3
   swh.scheduler[testing] >= 0.5.0
   dev: pdbpp
   pytest-cov
   django2: Django>=2,<3
 commands =
   pytest \
   !dev: --cov {envsitepackagesdir}/swh/deposit --cov-branch \
         {envsitepackagesdir}/swh/deposit \
         {posargs}
 
 [testenv:black]
 skip_install = true
 deps =
   black==19.10b0
 commands =
   {envpython} -m black --check swh
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8 \
     --exclude=.tox,.git,__pycache__,.tox,.eggs,*.egg,swh/deposit/migrations
 
 [testenv:mypy]
 setenv = DJANGO_SETTINGS_MODULE=swh.deposit.settings.testing
 extras =
   testing
 deps =
   mypy
 commands =
   mypy swh
+
+# build documentation outside swh-environment using the current
+# git HEAD of swh-docs, is executed on CI for each diff to prevent
+# breaking doc build
+[testenv:sphinx]
+whitelist_externals = make
+usedevelop = true
+extras =
+  testing
+deps =
+  # fetch and install swh-docs in develop mode
+  -e git+https://forge.softwareheritage.org/source/swh-docs#egg=swh.docs
+
+setenv =
+  SWH_PACKAGE_DOC_TOX_BUILD = 1
+  # turn warnings into errors
+  SPHINXOPTS = -W
+commands =
+  make -I ../.tox/sphinx/src/swh-docs/swh/ -C docs
+
+
+# build documentation only inside swh-environment using local state
+# of swh-docs package
+[testenv:sphinx-dev]
+whitelist_externals = make
+usedevelop = true
+extras =
+  testing
+deps =
+  # install swh-docs in develop mode
+  -e ../swh-docs
+
+setenv =
+  SWH_PACKAGE_DOC_TOX_BUILD = 1
+  # turn warnings into errors
+  SPHINXOPTS = -W
+commands =
+  make -I ../.tox/sphinx-dev/src/swh-docs/swh/ -C docs
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