diff --git a/.github/workflows/R.yml b/.github/workflows/R.yml
index 284c93df..07e5eaf5 100644
--- a/.github/workflows/R.yml
+++ b/.github/workflows/R.yml
@@ -190,8 +190,9 @@ jobs:
     needs: R-CMD-check
     permissions:
       contents: write # github-pages-deploy-action
+      pull-requests: write # post PR preview comment
     concurrency: # Recommended if you intend to make multiple deployments in quick succession.
-      group: web-${{ github.workflow }}-${{ github.ref }}
+      group: web-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
@@ -233,6 +234,46 @@ jobs:
           single-commit: true
           clean: true
 
+      - name: Deploy PR preview 🚀
+        if: success() && github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
+        uses: JamesIves/github-pages-deploy-action@v4
+        with:
+          folder: r/docs
+          target-folder: previews/pr-${{ github.event.pull_request.number }}/r
+          single-commit: true
+          clean: true
+
+      - name: Comment PR preview link
+        if: success() && github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const marker = '<!-- docs-preview-r-marker -->';
+            const prNumber = context.issue.number;
+            const url = `https://multi-objective.github.io/moocore/previews/pr-${prNumber}/r/`;
+            const body = `${marker}\n📚 [**R docs preview** for this PR](${url})\n\n`;
+            const comments = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: prNumber,
+            });
+            const existing = comments.data.find(c => c.body.includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: prNumber,
+                body,
+              });
+            }
+
   rchk:
     needs: pkgdown
     uses: multi-objective/moocore/.github/workflows/rchk.yml@main
diff --git a/.github/workflows/docs-preview-cleanup.yml b/.github/workflows/docs-preview-cleanup.yml
new file mode 100644
index 00000000..5ad60598
--- /dev/null
+++ b/.github/workflows/docs-preview-cleanup.yml
@@ -0,0 +1,34 @@
+name: Cleanup docs preview
+
+on:
+  pull_request:
+    types: [closed]
+
+permissions:
+  contents: write
+
+jobs:
+  cleanup:
+    name: Remove docs preview for closed PR
+    runs-on: ubuntu-latest
+    # Only run for same-repo PRs; fork PRs never get a preview deployed
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          ref: gh-pages
+
+      - name: Remove preview folder
+        run: |
+          PR_NUMBER="${{ github.event.pull_request.number }}"
+          PREVIEW_DIR="previews/pr-${PR_NUMBER}"
+          if [ -d "${PREVIEW_DIR}" ]; then
+            git rm -rf "${PREVIEW_DIR}"
+            git config user.email "actions@github.com"
+            git config user.name "GitHub Actions"
+            git commit -m "Remove docs preview for PR #${PR_NUMBER}"
+            git push
+            echo "Removed ${PREVIEW_DIR}"
+          else
+            echo "No preview directory found for PR #${PR_NUMBER}, nothing to clean up"
+          fi
diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 603dcc65..940cfcd9 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -117,8 +117,9 @@ jobs:
     if: "! contains(github.event.head_commit.message, '[skip ci]')"
     permissions:
       contents: write
+      pull-requests: write # post PR preview comment
     concurrency: # Recommended if you intend to make multiple deployments in quick succession.
-      group: web-${{ github.workflow }}-${{ github.ref }}
+      group: web-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
     timeout-minutes: 10
     runs-on:  ubuntu-latest
     steps:
@@ -165,6 +166,46 @@ jobs:
           single-commit: true
           clean: true
 
+      - name: Deploy PR preview 🚀
+        if: success() && github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
+        uses: JamesIves/github-pages-deploy-action@v4
+        with:
+          folder: python/doc/_build/html/
+          target-folder: previews/pr-${{ github.event.pull_request.number }}/python
+          single-commit: true
+          clean: true
+
+      - name: Comment PR preview link
+        if: success() && github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const marker = '<!-- docs-preview-python-marker -->';
+            const prNumber = context.issue.number;
+            const url = `https://multi-objective.github.io/moocore/previews/pr-${prNumber}/python/`;
+            const body = `${marker}\n📚 [**Python docs preview** for this PR](${url})\n\n`;
+            const comments = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: prNumber,
+            });
+            const existing = comments.data.find(c => c.body.includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: prNumber,
+                body,
+              });
+            }
+
   coverage:
     timeout-minutes: 15
     needs: build-doc