diff --git a/.github/workflows/daff.yml b/.github/workflows/daff.yml
new file mode 100644
index 0000000..7089e17
--- /dev/null
+++ b/.github/workflows/daff.yml
@@ -0,0 +1,45 @@
+name: Comment Diff
+
+on:
+  pull_request_target:
+    paths:
+      - 'Spreadsheet/**'
+
+jobs:
+  comment-diff:
+    runs-on: ubuntu-20.04
+    defaults:
+      run:
+        # The following allows for each run step to utilize ~/.bash_profile
+        # for setting up the per-step initial state.
+        # --login: a login shell. Source ~/.bash_profile
+        # -e: exit on first error
+        # -o pipefail: piped processes are important; fail if they fail
+        shell: bash --login -eo pipefail {0}
+    permissions:
+      pull-requests: write
+
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+        ref: ${{ github.head_ref }}
+
+    - name: install requirements
+      run: |
+        pip install --upgrade pip
+        pip install daff
+
+    - name: make diff
+      run: |
+        daff git csv
+        git config set --global diff.daff-csv.command "daff diff --git --output-format html --fragment --context 0"
+        git remote add target https://github.com/pcdshub/pcds-nalms.git
+        git fetch target
+        git diff target/${{ github.event.pull_request.base.ref }}...HEAD Spreadsheet/ > ${{ runner.temp }}/diff.txt
+
+    - name: make comment
+      uses: thollander/actions-comment-pull-request@v3
+      with:
+        file-path: ${{ runner.temp }}/diff.txt
+        comment-tag: csvdiff
\ No newline at end of file