diff --git a/activitypub.py b/activitypub.py
index f1de0a8..156a560 100644
--- a/activitypub.py
+++ b/activitypub.py
@@ -1,3 +1,4 @@
+import logging
 import json
 import binascii
 import os
@@ -21,6 +22,8 @@ import tasks
 from typing import List, Optional, Dict, Any, Union
 from typing import TypeVar
 
+logger = logging.getLogger(__name__)
+
 A = TypeVar('A', bound='BaseActivity')
 ObjectType = Dict[str, Any]
 ObjectOrIDType = Union[str, ObjectType]
@@ -454,6 +457,9 @@ class Follow(BaseActivity):
     def _undo_inbox(self) -> None:
         DB.followers.delete_one({'remote_actor': self.get_actor().id})
 
+    def _undo_outbox(self) -> None:
+        DB.following.delete_one({'remote_actor': self.get_object().id})
+
     def build_accept(self) -> BaseActivity:
         return self._build_reply(ActivityTypes.ACCEPT)
 
@@ -517,12 +523,17 @@ class Undo(BaseActivity):
         return False
 
     def _post_to_outbox(self, obj_id: str, activity: ObjectType, recipients: List[str]) -> None:
+        logger.debug('processing undo to outbox')
+        logger.debug('self={}'.format(self))
         obj = self.get_object()
+        logger.debug('obj={}'.format(obj))
         DB.outbox.update_one({'remote_id': obj.id}, {'$set': {'meta.undo': True}})
 
         try:
             obj._undo_outbox()
+            logger.debug(f'_undo_outbox called for {obj}')
         except NotImplementedError:
+            logger.debug(f'_undo_outbox not implemented for {obj}')
             pass
 
 
diff --git a/app.py b/app.py
index 0b19ef0..7eaf668 100644
--- a/app.py
+++ b/app.py
@@ -615,16 +615,25 @@ def ui_like():
     like.post_to_outbox()
     return redirect(request.args.get('redirect'))
 
-@app.route('/ui/undo')
-@login_required
-def ui_undo():
+@app.route('/api/undo', methods=['GET', 'POST'])
+@api_required
+def api_undo():
     oid = request.args.get('id')
-    doc =DB.outbox.find_one({'id': oid})
+    doc = DB.outbox.find_one({'$or': [{'id': oid}, {'remote_id': oid}]})
+    undo_id = None
     if doc:
         obj = activitypub.parse_activity(doc.get('activity'))
+        # FIXME(tsileo): detect already undo-ed and make this API call idempotent
         undo = obj.build_undo()
         undo.post_to_outbox()
-    return redirect(request.args.get('redirect'))
+        undo_id = undo.id
+    if request.args.get('redirect'):
+        return redirect(request.args.get('redirect'))
+    return Response(
+        status=201,
+        headers={'Microblogpub-Created-Activity': undo_id},
+    )
+
 
 @app.route('/stream')
 @login_required
@@ -823,6 +832,7 @@ def api_follow():
     follow.post_to_outbox()
     return Response(
         status=201,
+        headers={'Microblogpub-Created-Activity': follow.id},
     )
 
 
diff --git a/tests/federation_test.py b/tests/federation_test.py
index dc3d17d..ff8db17 100644
--- a/tests/federation_test.py
+++ b/tests/federation_test.py
@@ -58,6 +58,15 @@ class Instance(object):
 
         # We need to wait for the Follow/Accept dance
         time.sleep(10)
+        return resp.headers.get('microblogpub-created-activity')
+
+    def undo(self, oid: str) -> None:
+        resp = self.session.get(f'{self.host_url}/api/undo', params={'id': oid})
+        assert resp.status_code == 201
+
+        # We need to wait for the Follow/Accept dance
+        time.sleep(10)
+        return resp.headers.get('microblogpub-created-activity')
 
     def followers(self):
         resp = self.session.get(f'{self.host_url}/followers', headers={'Accept': 'application/activity+json'})
@@ -81,8 +90,7 @@ class Instance(object):
         return resp.json()
 
 
-def test_federation():
-    """Ensure the homepage is accessible."""
+def _instances():
     instance1 = Instance('http://localhost:5006', 'http://instance1_web_1:5005')
     instance1.ping()
 
@@ -94,16 +102,54 @@ def test_federation():
     instance1.drop_db()
     instance2.login()
     instance2.drop_db()
+    
+    return instance1, instance2
 
+
+def test_follow():
+    instance1, instance2 = _instances()
     # Instance1 follows instance2
     instance1.follow(instance2)
     instance1_debug = instance1.debug()
+    print(f'instance1_debug={instance1_debug}')
+    assert instance1_debug['inbox'] == 1  # An Accept activity should be there
+    assert instance1_debug['outbox'] == 1  # We've sent a Follow activity
+
+    instance2_debug = instance2.debug()
+    print(f'instance2_debug={instance2_debug}')
+    assert instance2_debug['inbox'] == 1  # An Follow activity should be there
+    assert instance2_debug['outbox'] == 1  # We've sent a Accept activity
+
+    assert instance2.followers() == [instance1.docker_url]
+    assert instance1.following() == [instance2.docker_url]
+
+
+def test_follow_unfollow():
+    instance1, instance2 = _instances()
+    # Instance1 follows instance2
+    follow_id = instance1.follow(instance2)
+    instance1_debug = instance1.debug()
     assert instance1_debug['inbox'] == 1  # An Accept activity should be there
     assert instance1_debug['outbox'] == 1  # We've sent a Follow activity
 
     instance2_debug = instance2.debug()
-    assert instance1_debug['inbox'] == 1  # An Follow activity should be there
-    assert instance1_debug['outbox'] == 1  # We've sent a Accept activity
+    assert instance2_debug['inbox'] == 1  # An Follow activity should be there
+    assert instance2_debug['outbox'] == 1  # We've sent a Accept activity
 
     assert instance2.followers() == [instance1.docker_url]
     assert instance1.following() == [instance2.docker_url]
+
+    instance1.undo(follow_id)
+
+    assert instance2.followers() == []
+    assert instance1.following() == []
+
+    instance1_debug = instance1.debug()
+    assert instance1_debug['inbox'] == 1  # An Accept activity should be there
+    assert instance1_debug['outbox'] == 2  # We've sent a Follow and a Undo activity
+
+    instance2_debug = instance2.debug()
+    assert instance2_debug['inbox'] == 2  # An Follow and Undo activity should be there
+    assert instance2_debug['outbox'] == 1  # We've sent a Accept activity
+
+