diff --git a/.cookiecutter/includes/tox/passenv b/.cookiecutter/includes/tox/passenv
index a913c55..344a0b1 100644
--- a/.cookiecutter/includes/tox/passenv
+++ b/.cookiecutter/includes/tox/passenv
@@ -1 +1,2 @@
+dev: GITHUB_ACTIONS
 dev: GITHUB_TOKEN
diff --git a/.github/workflows/alert.yml b/.github/workflows/alert.yml
index 59d1722..ed1a24a 100644
--- a/.github/workflows/alert.yml
+++ b/.github/workflows/alert.yml
@@ -37,7 +37,7 @@ jobs:
       - name: Post to Slack
         uses: slackapi/slack-github-action@v1.24.0
         with:
-          channel-id: ${{ vars.SLACK_CHANNEL }}
+          channel-id: C062HG8E691
           slack-message: ${{ env.SLACK_MESSAGE }}
         env:
           SLACK_MESSAGE: ${{ steps.slack_message.outputs.SLACK_MESSAGE }}
diff --git a/src/dependabot_alerts/cli.py b/src/dependabot_alerts/cli.py
index 08e9182..e2b2a12 100644
--- a/src/dependabot_alerts/cli.py
+++ b/src/dependabot_alerts/cli.py
@@ -1,13 +1,35 @@
+import subprocess
 from argparse import ArgumentParser
 from importlib.metadata import version
+from os import environ
 
+from dependabot_alerts.core import GitHub
 
-def cli(_argv=None):  # pylint:disable=inconsistent-return-statements
+
+def cli(argv=None):
     parser = ArgumentParser()
-    parser.add_argument("-v", "--version", action="store_true")
+    parser.add_argument(
+        "-v", "--version", action="version", version=version("dependabot-alerts")
+    )
+    parser.add_argument("organization", help="GitHub organization")
+
+    args = parser.parse_args(argv)
+    organization = args.organization
 
-    args = parser.parse_args(_argv)
+    github = GitHub(subprocess.run)
+    repos = github.alerts(organization)
 
-    if args.version:
-        print(version("dependabot-alerts"))
-        return 0
+    if environ.get("GITHUB_ACTIONS") == "true":
+        print(f"*Found Dependabot alerts in {len(repos.values())} repos:*")
+        print()
+        for repo, packages in repos.items():
+            for package, alerts in packages.items():
+                print(f"* {repo}: {package} ({len(alerts)} alerts)")
+        print()
+        print(
+            "Message generated by the `alerts.yml` workflow in dependabot-alerts (https://github.com/hypothesis/dependabot-alerts/blob/main/.github/workflows/alert.yml)"
+        )
+    else:
+        for repo, packages in repos.items():
+            for package, alerts in packages.items():
+                print(f"{repo}: {package} ({len(alerts)} alerts)")
diff --git a/src/dependabot_alerts/core.py b/src/dependabot_alerts/core.py
index d1b7a0d..ca79b69 100644
--- a/src/dependabot_alerts/core.py
+++ b/src/dependabot_alerts/core.py
@@ -1,2 +1,53 @@
+import json
+from collections import defaultdict
+from dataclasses import dataclass
+from functools import reduce
+
+
+def safe_get(dict_, keys):
+    return reduce(lambda d, k: d.get(k, {}), keys, dict_)
+
+
+@dataclass(frozen=True)
+class Alert:
+    repo: str
+    ecosystem: str
+    package: str
+
+    @classmethod
+    def make(cls, alert_dict):
+        return cls(
+            repo=safe_get(alert_dict, ["repository", "full_name"]),
+            ecosystem=safe_get(alert_dict, ["dependency", "package", "ecosystem"]),
+            package=safe_get(alert_dict, ["dependency", "package", "name"]),
+        )
+
+
+class GitHub:
+    def __init__(self, run):
+        self._run = run
+
+    def alerts(self, organization):
+        result = self._run(
+            [
+                "gh",
+                "api",
+                "--paginate",
+                f"/orgs/{organization}/dependabot/alerts?state=open",
+            ],
+            check=True,
+            capture_output=True,
+        )
+        alert_dicts = json.loads(result.stdout)
+
+        alerts = defaultdict(lambda: defaultdict(list))
+
+        for alert_dict in alert_dicts:
+            alert = Alert.make(alert_dict)
+            alerts[alert.repo][(alert.ecosystem, alert.package)].append(alert)
+
+        return alerts
+
+
 def hello_world():
     return "Hello, world!"
diff --git a/tox.ini b/tox.ini
index 846481c..4aac4e8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,6 +27,7 @@ passenv =
     dev: DEBUG
     dev: SENTRY_DSN
     dev: NEW_RELIC_LICENSE_KEY
+    dev: GITHUB_ACTIONS
     dev: GITHUB_TOKEN
 deps =
     dev: ipython