diff --git a/jay-config/src/_private.rs b/jay-config/src/_private.rs
index 2aa0c2ac..2845a2bc 100644
--- a/jay-config/src/_private.rs
+++ b/jay-config/src/_private.rs
@@ -109,6 +109,7 @@ pub enum WindowCriterionIpc {
         regex: bool,
     },
     Types(WindowType),
+    Client(ClientMatcher),
 }
 
 #[derive(Serialize, Deserialize, Clone, Debug, Hash, Eq, PartialEq)]
diff --git a/jay-config/src/_private/client.rs b/jay-config/src/_private/client.rs
index a1a7bc4c..77cb47d2 100644
--- a/jay-config/src/_private/client.rs
+++ b/jay-config/src/_private/client.rs
@@ -1638,6 +1638,7 @@ impl ConfigClient {
                 destroy_matcher,
             )
         };
+        let _destroy_client_matcher;
         let criterion = match criterion {
             WindowCriterion::Matcher(m) => return generic(GenericCriterion::Matcher(m)),
             WindowCriterion::Not(c) => return generic(GenericCriterion::Not(c)),
@@ -1645,6 +1646,13 @@ impl ConfigClient {
             WindowCriterion::Any(c) => return generic(GenericCriterion::Any(c)),
             WindowCriterion::Exactly(n, c) => return generic(GenericCriterion::Exactly(n, c)),
             WindowCriterion::Types(t) => WindowCriterionIpc::Types(t),
+            WindowCriterion::Client(c) => {
+                let (matcher, original) = self.create_client_matcher_(*c, true);
+                if original {
+                    _destroy_client_matcher = on_drop(move || matcher.destroy());
+                }
+                WindowCriterionIpc::Client(matcher)
+            }
         };
         let res = self.send_with_response(&ClientMessage::CreateWindowMatcher { criterion });
         get_response!(
diff --git a/jay-config/src/window.rs b/jay-config/src/window.rs
index 3205e36c..e8aeec2a 100644
--- a/jay-config/src/window.rs
+++ b/jay-config/src/window.rs
@@ -1,7 +1,10 @@
 //! Tools for inspecting and manipulating windows.
 
 use {
-    crate::{Axis, Direction, Workspace, client::Client},
+    crate::{
+        Axis, Direction, Workspace,
+        client::{Client, ClientCriterion},
+    },
     serde::{Deserialize, Serialize},
     std::ops::Deref,
 };
@@ -231,6 +234,8 @@ pub enum WindowCriterion<'a> {
     Any(&'a [WindowCriterion<'a>]),
     /// Matches if an exact number of the contained criteria match.
     Exactly(usize, &'a [WindowCriterion<'a>]),
+    /// Matches if the window's client matches the client criterion.
+    Client(&'a ClientCriterion<'a>),
 }
 
 impl WindowCriterion<'_> {
diff --git a/src/compositor.rs b/src/compositor.rs
index 1a2627d1..2c3352ee 100644
--- a/src/compositor.rs
+++ b/src/compositor.rs
@@ -230,6 +230,7 @@ fn start_compositor2(
             ipc_device_ids: Default::default(),
             use_wire_scale: Default::default(),
             wire_scale: Default::default(),
+            windows: Default::default(),
         },
         acceptor: Default::default(),
         serial: Default::default(),
diff --git a/src/config/handler.rs b/src/config/handler.rs
index b2adf0e9..abc51d60 100644
--- a/src/config/handler.rs
+++ b/src/config/handler.rs
@@ -1991,6 +1991,10 @@ impl ConfigProxyHandler {
                 match *field {}
             }
             WindowCriterionIpc::Types(t) => mgr.kind(*t),
+            WindowCriterionIpc::Client(c) => {
+                self.state.cl_matcher_manager.rematch_all(&self.state);
+                mgr.client(&self.state, &self.get_client_matcher(*c)?.node)
+            }
         };
         let cached = Rc::new(CachedCriterion {
             crit: criterion.clone(),
diff --git a/src/criteria/crit_graph.rs b/src/criteria/crit_graph.rs
index e7ed8be4..44d609a1 100644
--- a/src/criteria/crit_graph.rs
+++ b/src/criteria/crit_graph.rs
@@ -12,5 +12,7 @@ pub use {
         CritRootFixed,
     },
     crit_target::{CritMgr, CritTarget, CritTargetOwner, WeakCritTargetOwner},
-    crit_upstream::{CritUpstreamData, CritUpstreamNode},
+    crit_upstream::{
+        CritUpstreamData, CritUpstreamNode, CritUpstreamNodeBase, CritUpstreamNodeData,
+    },
 };
diff --git a/src/criteria/crit_graph/crit_upstream.rs b/src/criteria/crit_graph/crit_upstream.rs
index 5042e9a5..7e21c78e 100644
--- a/src/criteria/crit_graph/crit_upstream.rs
+++ b/src/criteria/crit_graph/crit_upstream.rs
@@ -55,7 +55,6 @@ where
     fn detach(&self, id: CritMatcherId);
     fn not(&self, mgr: &Target::Mgr) -> Rc<dyn CritUpstreamNode<Target>>;
     fn pull(&self, target: &Target) -> bool;
-    #[expect(dead_code)]
     fn get(&self, target: &Target) -> bool;
 }
 
diff --git a/src/criteria/tlm.rs b/src/criteria/tlm.rs
index 376af00f..96581ece 100644
--- a/src/criteria/tlm.rs
+++ b/src/criteria/tlm.rs
@@ -5,10 +5,11 @@ use {
         criteria::{
             CritDestroyListener, CritMatcherId, CritMatcherIds, CritMgrExt, CritUpstreamNode,
             FixedRootMatcher, RootMatcherMap,
+            clm::ClmUpstreamNode,
             crit_graph::{CritMgr, CritTarget, CritTargetOwner, WeakCritTargetOwner},
             crit_leaf::{CritLeafEvent, CritLeafMatcher},
             crit_matchers::critm_constant::CritMatchConstant,
-            tlm::tlm_matchers::tlmm_kind::TlmMatchKind,
+            tlm::tlm_matchers::{tlmm_client::TlmMatchClient, tlmm_kind::TlmMatchKind},
         },
         state::State,
         tree::{NodeId, ToplevelData, ToplevelNode},
@@ -42,6 +43,7 @@ type TlmRootMatcherMap<T> = RootMatcherMap<ToplevelData, T>;
 #[derive(Default)]
 pub struct RootMatchers {
     kinds: TlmRootMatcherMap<TlmMatchKind>,
+    clients: CopyHashMap<CritMatcherId, Weak<TlmMatchClient>>,
 }
 
 pub async fn handle_tl_changes(state: Rc<State>) {
@@ -115,6 +117,7 @@ impl TlMatcherManager {
                 };
             }
             unconditional!(kinds);
+            unconditional!(clients);
             if self.constant[true].has_downstream() {
                 return true;
             }
@@ -182,6 +185,7 @@ impl TlMatcherManager {
                 };
             }
             unconditional!(kinds);
+            unconditional!(clients);
             self.constant[true].handle(data);
         }
         #[expect(unused_macros)]
@@ -207,6 +211,10 @@ impl TlMatcherManager {
     pub fn kind(&self, kind: WindowType) -> Rc<TlmUpstreamNode> {
         self.root(TlmMatchKind::new(kind))
     }
+
+    pub fn client(&self, state: &Rc<State>, client: &Rc<ClmUpstreamNode>) -> Rc<TlmUpstreamNode> {
+        TlmMatchClient::new(state, client)
+    }
 }
 
 impl CritTarget for ToplevelData {
diff --git a/src/criteria/tlm/tlm_matchers.rs b/src/criteria/tlm/tlm_matchers.rs
index 93871e79..4348b709 100644
--- a/src/criteria/tlm/tlm_matchers.rs
+++ b/src/criteria/tlm/tlm_matchers.rs
@@ -18,4 +18,5 @@ macro_rules! fixed_root_criterion {
     };
 }
 
+pub mod tlmm_client;
 pub mod tlmm_kind;
diff --git a/src/criteria/tlm/tlm_matchers/tlmm_client.rs b/src/criteria/tlm/tlm_matchers/tlmm_client.rs
new file mode 100644
index 00000000..f9dc83ad
--- /dev/null
+++ b/src/criteria/tlm/tlm_matchers/tlmm_client.rs
@@ -0,0 +1,117 @@
+use {
+    crate::{
+        client::Client,
+        criteria::{
+            CritMatcherId, CritUpstreamNode,
+            clm::ClmUpstreamNode,
+            crit_graph::{
+                CritDownstream, CritDownstreamData, CritMgr, CritUpstreamData,
+                CritUpstreamNodeBase, CritUpstreamNodeData,
+            },
+            crit_per_target_data::{CritDestroyListenerBase, CritPerTargetData},
+            tlm::TlMatcherManager,
+        },
+        state::State,
+        tree::{ToplevelData, ToplevelNodeBase},
+    },
+    std::rc::Rc,
+};
+
+pub struct TlmMatchClient {
+    id: CritMatcherId,
+    state: Rc<State>,
+    node: Rc<ClmUpstreamNode>,
+    upstream: CritDownstreamData<Rc<Client>>,
+    downstream: CritUpstreamData<ToplevelData, ()>,
+}
+
+impl TlmMatchClient {
+    pub fn new(state: &Rc<State>, node: &Rc<ClmUpstreamNode>) -> Rc<TlmMatchClient> {
+        let id = state.tl_matcher_manager.id();
+        let slf = Rc::new_cyclic(|slf| Self {
+            id,
+            state: state.clone(),
+            node: node.clone(),
+            upstream: CritDownstreamData::new(id, &[node.clone()]),
+            downstream: CritUpstreamData::new(slf, id),
+        });
+        slf.upstream.attach(&slf);
+        state
+            .tl_matcher_manager
+            .matchers
+            .clients
+            .set(id, Rc::downgrade(&slf));
+        slf
+    }
+
+    pub fn handle(&self, node: &ToplevelData) {
+        if let Some(client) = &node.client {
+            if self.node.get(client) {
+                let data = self.downstream.get_or_create(node);
+                self.downstream.update_matched(node, data, true, false);
+            }
+        }
+    }
+}
+
+impl CritUpstreamNodeBase<ToplevelData> for TlmMatchClient {
+    type Data = ();
+
+    fn data(&self) -> &CritUpstreamData<ToplevelData, Self::Data> {
+        &self.downstream
+    }
+
+    fn not(&self, _mgr: &TlMatcherManager) -> Rc<dyn CritUpstreamNode<ToplevelData>> {
+        Self::new(&self.state, &self.node.not(&self.state.cl_matcher_manager))
+    }
+
+    fn pull(&self, target: &ToplevelData) -> bool {
+        if let Some(client) = &target.client {
+            return self.node.pull(client);
+        }
+        false
+    }
+}
+
+impl CritDownstream<Rc<Client>> for TlmMatchClient {
+    fn update_matched(self: Rc<Self>, target: &Rc<Client>, matched: bool) {
+        let handle = |data: &ToplevelData| {
+            let node = match matched {
+                true => self.downstream.get_or_create(data),
+                false => match self.downstream.get(data) {
+                    Some(n) => n,
+                    None => return,
+                },
+            };
+            self.downstream
+                .update_matched(data, node, matched, !matched);
+        };
+        if target.is_xwayland {
+            for tl in self.state.xwayland.windows.lock().values() {
+                handle(tl.tl_data());
+            }
+        } else {
+            for tl in target.objects.xdg_toplevel.lock().values() {
+                handle(tl.tl_data());
+            }
+        }
+    }
+}
+
+impl CritDestroyListenerBase<ToplevelData> for TlmMatchClient {
+    type Data = CritUpstreamNodeData<ToplevelData, ()>;
+
+    fn data(&self) -> &CritPerTargetData<ToplevelData, Self::Data> {
+        &self.downstream.nodes
+    }
+}
+
+impl Drop for TlmMatchClient {
+    fn drop(&mut self) {
+        self.state
+            .tl_matcher_manager
+            .matchers
+            .clients
+            .remove(&self.id);
+    }
+}
diff --git a/src/ifs/wl_surface/x_surface/xwindow.rs b/src/ifs/wl_surface/x_surface/xwindow.rs
index 1c6664c2..b6ca97be 100644
--- a/src/ifs/wl_surface/x_surface/xwindow.rs
+++ b/src/ifs/wl_surface/x_surface/xwindow.rs
@@ -238,6 +238,13 @@ impl Xwindow {
         self.tl_destroy();
         self.x.surface.set_toplevel(None);
         self.x.xwindow.set(None);
+        self.x
+            .surface
+            .client
+            .state
+            .xwayland
+            .windows
+            .remove(&self.id);
     }
 
     pub fn is_mapped(&self) -> bool {
diff --git a/src/state.rs b/src/state.rs
index b0dd776f..f870ac9e 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -57,6 +57,7 @@ use {
                 NoneSurfaceExt,
                 tray::TrayItemIds,
                 wl_subsurface::SubsurfaceIds,
+                x_surface::xwindow::{Xwindow, XwindowId},
                 zwp_idle_inhibitor_v1::{IdleInhibitorId, IdleInhibitorIds, ZwpIdleInhibitorV1},
                 zwp_input_popup_surface_v2::ZwpInputPopupSurfaceV2,
             },
@@ -271,6 +272,7 @@ pub struct XWaylandState {
     pub ipc_device_ids: XIpcDeviceIds,
     pub use_wire_scale: Cell<bool>,
     pub wire_scale: Cell<Option<i32>>,
+    pub windows: CopyHashMap<XwindowId, Rc<Xwindow>>,
 }
 
 pub struct IdleState {
diff --git a/src/xwayland/xwm.rs b/src/xwayland/xwm.rs
index 1d5f0b33..e809f8b3 100644
--- a/src/xwayland/xwm.rs
+++ b/src/xwayland/xwm.rs
@@ -1459,6 +1459,7 @@ impl Wm {
                 return;
             }
         };
+        self.state.xwayland.windows.set(window.id, window.clone());
         data.window.set(Some(window.clone()));
         {
             self.load_window_wm_class(data).await;
diff --git a/toml-config/src/config.rs b/toml-config/src/config.rs
index 2360fc77..40bd2e4d 100644
--- a/toml-config/src/config.rs
+++ b/toml-config/src/config.rs
@@ -254,6 +254,7 @@ pub struct WindowRule {
 pub struct WindowMatch {
     pub generic: GenericMatch<Self>,
     pub types: Option<WindowType>,
+    pub client: Option<ClientMatch>,
 }
 
 #[derive(Debug, Clone)]
diff --git a/toml-config/src/config/parsers/window_match.rs b/toml-config/src/config/parsers/window_match.rs
index 3c41403d..4836a48b 100644
--- a/toml-config/src/config/parsers/window_match.rs
+++ b/toml-config/src/config/parsers/window_match.rs
@@ -5,7 +5,10 @@ use {
             context::Context,
             extractor::{Extractor, ExtractorError, arr, n32, opt, str, val},
             parser::{DataType, ParseResult, Parser, UnexpectedDataType},
-            parsers::window_type::{WindowTypeParser, WindowTypeParserError},
+            parsers::{
+                client_match::{ClientMatchParser, ClientMatchParserError},
+                window_type::{WindowTypeParser, WindowTypeParserError},
+            },
         },
         toml::{
             toml_span::{DespanExt, Span, Spanned},
@@ -24,6 +27,8 @@ pub enum WindowMatchParserError {
     Extract(#[from] ExtractorError),
     #[error(transparent)]
     WindowTypes(#[from] WindowTypeParserError),
+    #[error(transparent)]
+    ClientMatchParserError(#[from] ClientMatchParserError),
 }
 
 pub struct WindowMatchParser<'a>(pub &'a Context<'a>);
@@ -39,14 +44,16 @@ impl Parser for WindowMatchParser<'_> {
         table: &IndexMap<Spanned<String>, Spanned<Value>>,
     ) -> ParseResult<Self> {
         let mut ext = Extractor::new(self.0, span, table);
-        let ((name, not_val, all_val, any_val, exactly_val, types_val),) = ext.extract(((
-            opt(str("name")),
-            opt(val("not")),
-            opt(arr("all")),
-            opt(arr("any")),
-            opt(val("exactly")),
-            opt(val("types")),
-        ),))?;
+        let ((name, not_val, all_val, any_val, exactly_val, types_val, client_val),) = ext
+            .extract(((
+                opt(str("name")),
+                opt(val("not")),
+                opt(arr("all")),
+                opt(arr("any")),
+                opt(val("exactly")),
+                opt(val("types")),
+                opt(val("client")),
+            ),))?;
         let mut not = None;
         if let Some(value) = not_val {
             not = Some(Box::new(value.parse(&mut WindowMatchParser(self.0))?));
@@ -74,6 +81,10 @@ impl Parser for WindowMatchParser<'_> {
         if let Some(value) = exactly_val {
             exactly = Some(value.parse(&mut WindowMatchExactlyParser(self.0))?);
         }
+        let mut client = None;
+        if let Some(value) = client_val {
+            client = Some(value.parse_map(&mut ClientMatchParser(self.0))?);
+        }
         Ok(WindowMatch {
             generic: GenericMatch {
                 name: name.despan_into(),
@@ -83,6 +94,7 @@ impl Parser for WindowMatchParser<'_> {
                 exactly,
             },
             types,
+            client,
         })
     }
 }
diff --git a/toml-config/src/rules.rs b/toml-config/src/rules.rs
index 7b5d256a..d7cf586b 100644
--- a/toml-config/src/rules.rs
+++ b/toml-config/src/rules.rs
@@ -219,7 +219,7 @@ impl Rule for WindowRule {
     }
 
     fn map_custom(
-        _state: &Rc<State>,
+        state: &Rc<State>,
         all: &mut Vec<MatcherTemp<Self>>,
         match_: &Self::Match,
     ) -> Option<()> {
@@ -248,6 +248,14 @@ impl Rule for WindowRule {
         if let Some(value) = &match_.types {
             all.push(m(WindowCriterion::Types(*value)));
         }
+        if let Some(value) = &match_.client {
+            let mut mapper = state.persistent.client_rule_mapper.borrow_mut();
+            let mapper = mapper.as_mut()?;
+            let matcher = mapper.map_temporary_match(&[], value)?;
+            all.push(m(WindowCriterion::Client(&ClientCriterion::Matcher(
+                matcher.0,
+            ))));
+        }
         Some(())
     }
 
diff --git a/toml-spec/spec/spec.generated.json b/toml-spec/spec/spec.generated.json
index 1b562e07..79ab0227 100644
--- a/toml-spec/spec/spec.generated.json
+++ b/toml-spec/spec/spec.generated.json
@@ -1775,6 +1775,10 @@
         "types": {
           "description": "Matches windows whose type is contained in the mask.",
           "$ref": "#/$defs/WindowTypeMask"
+        },
+        "client": {
+          "description": "Matches if the window's client matches the client criterion.",
+          "$ref": "#/$defs/ClientMatch"
         }
       },
       "required": []
diff --git a/toml-spec/spec/spec.generated.md b/toml-spec/spec/spec.generated.md
index 97245dfd..0b96cbf0 100644
--- a/toml-spec/spec/spec.generated.md
+++ b/toml-spec/spec/spec.generated.md
@@ -4004,6 +4004,12 @@ The table has the following fields:
 
   The value of this field should be a [WindowTypeMask](#types-WindowTypeMask).
 
+- `client` (optional):
+
+  Matches if the window's client matches the client criterion.
+
+  The value of this field should be a [ClientMatch](#types-ClientMatch).
+
 
 <a name="types-WindowMatchExactly"></a>
 ### `WindowMatchExactly`
diff --git a/toml-spec/spec/spec.yaml b/toml-spec/spec/spec.yaml
index c243a6aa..2f1f2ea3 100644
--- a/toml-spec/spec/spec.yaml
+++ b/toml-spec/spec/spec.yaml
@@ -3463,6 +3463,10 @@ WindowMatch:
       ref: WindowTypeMask
       required: false
       description: Matches windows whose type is contained in the mask.
+    client:
+      ref: ClientMatch
+      required: false
+      description: Matches if the window's client matches the client criterion.
 
 
 WindowMatchExactly: