diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2787d22..3b785aa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -66,7 +66,7 @@ jobs:
     - name: Install Linux packages
       run: |
         sudo apt-get update
-        sudo apt-get install -y rclone openssh-server
+        sudo apt-get install -y rclone openssh-server curl
     - name: Configure OpenSSH SFTP server (test only)
       run: |
         sudo mkdir -p /run/sshd
@@ -95,6 +95,31 @@ jobs:
         ssh-add ~/.ssh/id_ed25519
         # Export SFTP test URL for tox via GITHUB_ENV
         echo "BORGSTORE_TEST_SFTP_URL=sftp://sftpuser@localhost:22/borgstore/temp-store" >> $GITHUB_ENV
+    - name: Install and configure MinIO S3 server (test only)
+      run: |
+        set -e
+        arch=$(uname -m)
+        case "$arch" in
+          x86_64|amd64) srv_url=https://dl.min.io/server/minio/release/linux-amd64/minio; cli_url=https://dl.min.io/client/mc/release/linux-amd64/mc ;;
+          aarch64|arm64) srv_url=https://dl.min.io/server/minio/release/linux-arm64/minio; cli_url=https://dl.min.io/client/mc/release/linux-arm64/mc ;;
+          *) echo "Unsupported arch: $arch"; exit 1 ;;
+        esac
+        curl -fsSL -o /usr/local/bin/minio "$srv_url"
+        curl -fsSL -o /usr/local/bin/mc "$cli_url"
+        sudo chmod +x /usr/local/bin/minio /usr/local/bin/mc
+        export PATH=/usr/local/bin:$PATH
+        # Start MinIO on :9000 with default credentials (minioadmin/minioadmin)
+        MINIO_DIR="$GITHUB_WORKSPACE/.minio-data"
+        MINIO_LOG="$GITHUB_WORKSPACE/.minio.log"
+        mkdir -p "$MINIO_DIR"
+        nohup minio server "$MINIO_DIR" --address ":9000" >"$MINIO_LOG" 2>&1 &
+        # Wait for MinIO port to be ready
+        for i in $(seq 1 60); do (echo > /dev/tcp/127.0.0.1/9000) >/dev/null 2>&1 && break; sleep 1; done
+        # Configure client and create bucket
+        mc alias set local http://127.0.0.1:9000 minioadmin minioadmin
+        mc mb --ignore-existing local/test
+        # Export S3 test URL for tox via GITHUB_ENV
+        echo "BORGSTORE_TEST_S3_URL=s3:minioadmin:minioadmin@http://127.0.0.1:9000/test/path" >> $GITHUB_ENV
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:
@@ -103,7 +128,8 @@ jobs:
       run: |
         python -m pip install --upgrade pip setuptools
         pip install -r requirements.d/dev.txt
-    - name: Install borgstore (with sftp extra)
-      run: pip install -ve ".[sftp]"
-    - name: run tox env
-      run: tox -e sftp
+    - name: Install borgstore (with all extras)
+      run: pip install -ve ".[s3,sftp]"
+    - name: run tox envs
+      run: |
+        tox -e all_extras
diff --git a/tox.ini b/tox.ini
index 4992f90..c25dded 100644
--- a/tox.ini
+++ b/tox.ini
@@ -40,3 +40,12 @@ deps =
 commands = pytest -v -rs tests
 pass_env =
     BORGSTORE_TEST_SFTP_URL
+
+[testenv:all_extras]
+deps =
+    pytest
+    boto3
+    paramiko
+commands = pytest -v -rs tests
+pass_env =
+    BORGSTORE_TEST_*_URL