diff --git a/client/css/post-upload.styl b/client/css/post-upload.styl
index ea79fcac..cb6b0067 100644
--- a/client/css/post-upload.styl
+++ b/client/css/post-upload.styl
@@ -62,6 +62,14 @@ $cancel-button-color = tomato
             margin: 0 0 1.2em 0
             padding-left: 13em
 
+            img
+                width: 100%
+                height: 100%
+            
+            video
+                width: 100%
+                height: 100%
+
             &>.thumbnail-wrapper
                 float: left
                 width: 12em
diff --git a/doc/API.md b/doc/API.md
index 30773c8f..4d5791cf 100644
--- a/doc/API.md
+++ b/doc/API.md
@@ -323,7 +323,7 @@ data.
     {
         "name":  <name>,
         "color": <color>,
-        "order": <order>  // optional
+        "order": <order>
     }
     ```
 
@@ -2528,7 +2528,7 @@ One file together with its metadata posted to the site.
 ## Micro post
 **Description**
 
-A [post resource](#post) stripped down to `name` and `thumbnailUrl` fields.
+A [post resource](#post) stripped down to `id` and `thumbnailUrl` fields.
 
 ## Note
 **Description**
diff --git a/server/szurubooru/search/configs/post_search_config.py b/server/szurubooru/search/configs/post_search_config.py
index ddc003b7..8d4672d4 100644
--- a/server/szurubooru/search/configs/post_search_config.py
+++ b/server/szurubooru/search/configs/post_search_config.py
@@ -122,6 +122,34 @@ def _pool_filter(
     )(query, criterion, negated)
 
 
+def _category_filter(
+    query: SaQuery, criterion: Optional[criteria.BaseCriterion], negated: bool
+) -> SaQuery:
+    assert criterion
+
+    # Step 1. find the id for the category
+    q1 = db.session.query(model.TagCategory.tag_category_id).filter(
+        model.TagCategory.name == criterion.value
+    )
+
+    # Step 2. find the tags with that category
+    q2 = db.session.query(model.Tag.tag_id).filter(
+        model.Tag.category_id.in_(q1)
+    )
+
+    # Step 3. find all posts that have at least one of those tags
+    q3 = db.session.query(model.PostTag.post_id).filter(
+        model.PostTag.tag_id.in_(q2)
+    )
+
+    # Step 4. profit
+    expr = model.Post.post_id.in_(q3)
+    if negated:
+        expr = ~expr
+
+    return query.filter(expr)
+
+
 class PostSearchConfig(BaseSearchConfig):
     def __init__(self) -> None:
         self.user = None  # type: Optional[model.User]
@@ -349,6 +377,7 @@ class PostSearchConfig(BaseSearchConfig):
                     ),
                 ),
                 (["pool"], _pool_filter),
+                (["category"], _category_filter),
             ]
         )
 
diff --git a/server/szurubooru/tests/search/configs/test_post_search_config.py b/server/szurubooru/tests/search/configs/test_post_search_config.py
index 4fb8191a..b86fa273 100644
--- a/server/szurubooru/tests/search/configs/test_post_search_config.py
+++ b/server/szurubooru/tests/search/configs/test_post_search_config.py
@@ -863,3 +863,55 @@ def test_tumbleweed(
     db.session.flush()
     verify_unpaged("special:tumbleweed", [4])
     verify_unpaged("-special:tumbleweed", [1, 2, 3])
+
+
+@pytest.mark.parametrize(
+    "input,expected_post_ids",
+    [
+        ("category:cat1", [1, 2, 3]),
+        ("category:cat2", [3, 4]),
+    ],
+)
+def test_search_by_tag_category(
+    verify_unpaged,
+    post_factory,
+    tag_factory,
+    tag_category_factory,
+    input,
+    expected_post_ids,
+):
+    cat1 = tag_category_factory(name="cat1")
+    cat2 = tag_category_factory(name="cat2")
+    tag1 = tag_factory(names=["t1"], category=cat1)
+    tag2 = tag_factory(names=["t2"], category=cat1)
+    tag3 = tag_factory(names=["t3"], category=cat2)
+
+    post1 = post_factory(id=1)
+    post1.tags.append(tag1)
+
+    post2 = post_factory(id=2)
+    post2.tags.append(tag2)
+
+    post3 = post_factory(id=3)
+    post3.tags.append(tag1)
+    post3.tags.append(tag3)
+
+    post4 = post_factory(id=4)
+    post4.tags.append(tag3)
+
+    post5 = post_factory(id=5)
+
+    db.session.add_all(
+        [
+            tag1,
+            tag2,
+            tag3,
+            post1,
+            post2,
+            post3,
+            post4,
+            post5,
+        ]
+    )
+    db.session.flush()
+    verify_unpaged(input, expected_post_ids)