diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 60f296b1d..cd947b3ef 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -105,6 +105,22 @@ jobs:
         weechat --version
         weechat --run-command "/debug dirs;/debug libs" --run-command "/quit"
 
+    - name: Test Relay OpenAPI
+      if: ${{ matrix.config.name == 'gcc' }}
+      env:
+        RELAY_PASSWORD: test
+      run: |
+        sudo -H pip3 install --ignore-installed schemathesis
+        weechat-headless \
+          --dir /tmp/weechat-test-api \
+          --run-command '/set relay.network.password "${{ env.RELAY_PASSWORD }}"' \
+          --run-command '/relay add api 9000' \
+          --daemon \
+        ;
+        sleep 5
+        ./tools/test_relay_api.sh http://localhost:9000
+        echo '*/quit' >/tmp/weechat-test-api/weechat_fifo_*
+
     - name: Code coverage
       if: ${{ matrix.config.name == 'gcc_coverage' }}
       env:
diff --git a/tools/test_relay_api.sh b/tools/test_relay_api.sh
new file mode 100755
index 000000000..4a830826f
--- /dev/null
+++ b/tools/test_relay_api.sh
@@ -0,0 +1,86 @@
+#!/bin/sh
+#
+# Copyright (C) 2024 Sébastien Helleu <flashcode@flashtux.org>
+#
+# This file is part of WeeChat, the extensible chat client.
+#
+# WeeChat is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# WeeChat is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with WeeChat.  If not, see <https://www.gnu.org/licenses/>.
+#
+
+#
+# Test WeeChat relay HTTP REST API.
+#
+# Environment variables that can be used:
+#
+#   RELAY_PASSWORD  Password for WeeChat relay
+#
+
+set -o errexit
+
+# default values for options from environment variables
+default_relay_password="test"
+
+usage ()
+{
+    rc=$1
+    cat <<-EOF
+
+Syntax: $0 url
+
+  url  URL of the running WeeChat with relay api (without "/api")
+
+Environment variables used:
+
+  RELAY_PASSWORD  password for the relay (default: "${default_relay_password}")
+
+Example:
+
+  RELAY_PASSWORD="test" $0 http://localhost:9000
+
+EOF
+    exit "${rc}"
+}
+
+error_usage ()
+{
+    echo >&2 "ERROR: $*"
+    usage 1
+}
+
+# ================================== START ==================================
+
+# relay password
+[ -z "${RELAY_PASSWORD}" ] && RELAY_PASSWORD="${default_relay_password}"
+
+# check command line arguments
+if [ $# -eq 0 ]; then
+    usage 0
+fi
+if [ $# -lt 1 ]; then
+    error_usage "missing arguments"
+fi
+
+# command line arguments
+url="$1"
+
+schemathesis run \
+    --checks all \
+    --validate-schema=true \
+    --experimental=openapi-3.1 \
+    --base-url "${url}/api" \
+    --auth "plain:${RELAY_PASSWORD}" \
+    ./src/plugins/relay/api/weechat-relay-api.yaml \
+    ;
+
+exit 0