diff --git a/config/parameters.go b/config/parameters.go
index e59b76e..4609ce6 100644
--- a/config/parameters.go
+++ b/config/parameters.go
@@ -23,7 +23,6 @@ func (c *Config) LoadParameters(params *mpb.GetParametersResponse) error {
 	c.WebsocketServer.Limitation = &websocket.Limitation{
 		MaxMessageLength:    params.Limitations.MaxMessageLength,
 		MaxSubscriptions:    params.Limitations.MaxSubscriptions,
-		MaxFilters:          params.Limitations.MaxFilters,
 		MaxSubidLength:      params.Limitations.MaxSubidLength,
 		MinPowDifficulty:    params.Limitations.MinPowDifficulty,
 		AuthRequired:        params.Limitations.AuthRequired,
diff --git a/delivery/websocket/client_state.go b/delivery/websocket/client_state.go
index e9a12a1..7c8e6ba 100644
--- a/delivery/websocket/client_state.go
+++ b/delivery/websocket/client_state.go
@@ -10,6 +10,6 @@ type clientState struct {
 	challenge string
 	pubkey    *string
 	isKnown   *bool
-	subs      map[string]filter.Filters
+	subs      map[string]filter.Filter
 	*sync.RWMutex
 }
diff --git a/delivery/websocket/config.go b/delivery/websocket/config.go
index 650e0cc..8a5ce50 100644
--- a/delivery/websocket/config.go
+++ b/delivery/websocket/config.go
@@ -5,7 +5,6 @@ import "net/url"
 type Limitation struct {
 	MaxMessageLength    int32 // todo?.
 	MaxSubscriptions    int32
-	MaxFilters          int32
 	MaxSubidLength      int32
 	MinPowDifficulty    int32
 	AuthRequired        bool
diff --git a/delivery/websocket/event_handler.go b/delivery/websocket/event_handler.go
index 471d529..255b292 100644
--- a/delivery/websocket/event_handler.go
+++ b/delivery/websocket/event_handler.go
@@ -9,13 +9,15 @@ import (
 	"github.com/dezh-tech/immortal/infrastructure/redis"
 	"github.com/dezh-tech/immortal/pkg/logger"
 	"github.com/dezh-tech/immortal/pkg/utils"
+	"github.com/dezh-tech/immortal/types"
+	"github.com/dezh-tech/immortal/types/filter"
 	"github.com/dezh-tech/immortal/types/message"
 	"github.com/gorilla/websocket"
 	gredis "github.com/redis/go-redis/v9"
 )
 
 // handleEvent handles new incoming EVENT messages from client.
-func (s *Server) handleEvent(conn *websocket.Conn, m message.Message) {
+func (s *Server) handleEvent(conn *websocket.Conn, m message.Message) { //nolint
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	defer measureLatency(s.metrics.EventLatency)()
@@ -172,9 +174,59 @@ func (s *Server) handleEvent(conn *websocket.Conn, m message.Message) {
 		return
 	}
 
-	if !msg.Event.Kind.IsEphemeral() {
-		err := s.handler.HandleEvent(msg.Event)
-		if err != nil {
+	if !msg.Event.Kind.IsEphemeral() { //nolint
+		if msg.Event.Kind == types.KindEventDeletionRequest {
+			deleteFilterString := msg.Event.Tags.GetValue("filter")
+
+			deleteFilter, err := filter.Decode([]byte(deleteFilterString))
+			if err != nil {
+				okm := message.MakeOK(false,
+					msg.Event.ID,
+					fmt.Sprintf("error: parse deletion event: %s", deleteFilterString),
+				)
+
+				_ = conn.WriteMessage(1, okm)
+
+				status = invalidFail
+
+				return
+			}
+
+			// you can only delete events you own.
+			if len(deleteFilter.Authors) == 1 {
+				if deleteFilter.Authors[0] != msg.Event.PublicKey {
+					okm := message.MakeOK(false,
+						msg.Event.ID,
+						fmt.Sprintf(
+							"error: you can request to delete your events only: %s",
+							deleteFilter.Authors),
+					)
+
+					_ = conn.WriteMessage(1, okm)
+
+					status = invalidFail
+
+					return
+				}
+			} else {
+				okm := message.MakeOK(false,
+					msg.Event.ID,
+					fmt.Sprintf(
+						"error: you can request to delete your events only: %s",
+						deleteFilter.Authors),
+				)
+
+				_ = conn.WriteMessage(1, okm)
+
+				status = invalidFail
+
+				return
+			}
+
+			go s.handler.DeleteByFilter(deleteFilter) //nolint
+		}
+
+		if err := s.handler.HandleEvent(msg.Event); err != nil {
 			okm := message.MakeOK(false,
 				msg.Event.ID,
 				"error: can't write event to database.",
diff --git a/delivery/websocket/req_handler.go b/delivery/websocket/req_handler.go
index a9f1c71..e63fb32 100644
--- a/delivery/websocket/req_handler.go
+++ b/delivery/websocket/req_handler.go
@@ -55,15 +55,6 @@ func (s *Server) handleReq(conn *websocket.Conn, m message.Message) {
 		return
 	}
 
-	if len(msg.Filters) >= int(s.config.Limitation.MaxFilters) {
-		_ = conn.WriteMessage(1, message.MakeNotice(fmt.Sprintf("error: max limit of filters is: %d",
-			s.config.Limitation.MaxFilters)))
-
-		status = limitsFail
-
-		return
-	}
-
 	if len(msg.SubscriptionID) >= int(s.config.Limitation.MaxSubidLength) {
 		_ = conn.WriteMessage(1, message.MakeNotice(fmt.Sprintf("error: max limit of sub id is: %d",
 			s.config.Limitation.MaxSubidLength)))
@@ -82,7 +73,7 @@ func (s *Server) handleReq(conn *websocket.Conn, m message.Message) {
 		return
 	}
 
-	res, err := s.handler.HandleReq(msg.Filters)
+	res, err := s.handler.HandleReq(&msg.Filter)
 	if err != nil {
 		_ = conn.WriteMessage(1, message.MakeNotice(fmt.Sprintf("error: can't process REQ message: %s", err.Error())))
 		status = databaseFail
@@ -99,6 +90,6 @@ func (s *Server) handleReq(conn *websocket.Conn, m message.Message) {
 
 	client.Lock()
 	s.metrics.Subscriptions.Inc()
-	client.subs[msg.SubscriptionID] = msg.Filters
+	client.subs[msg.SubscriptionID] = msg.Filter
 	client.Unlock()
 }
diff --git a/delivery/websocket/server.go b/delivery/websocket/server.go
index 388f782..5548ac9 100644
--- a/delivery/websocket/server.go
+++ b/delivery/websocket/server.go
@@ -82,7 +82,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	s.conns[conn] = clientState{
 		pubkey:  &pubkey,
 		isKnown: &known,
-		subs:    make(map[string]filter.Filters),
+		subs:    make(map[string]filter.Filter),
 		RWMutex: &sync.RWMutex{},
 	}
 
diff --git a/documents/NIPs.md b/documents/NIPs.md
index ab40ae6..fdf9404 100644
--- a/documents/NIPs.md
+++ b/documents/NIPs.md
@@ -1,7 +1,7 @@
 # Immortal supported NIPs
 
 - [X] **NIP-01**: Basic Protocol Flow Description
-- [ ] **NIP-09**: Event Deletion Request
+- [X] **NIP-09**: Event Deletion Request
 - [X] **NIP-11**: Relay Information Document
 - [X] **NIP-13**: Proof of Work
 - [X] **NIP-40**: Expiration Timestamp
diff --git a/infrastructure/grpc_client/gen/config.pb.go b/infrastructure/grpc_client/gen/config.pb.go
index 3f2c5a2..9835e63 100644
--- a/infrastructure/grpc_client/gen/config.pb.go
+++ b/infrastructure/grpc_client/gen/config.pb.go
@@ -27,7 +27,6 @@ type Limitations struct {
 
 	MaxMessageLength    int32  `protobuf:"varint,1,opt,name=max_message_length,json=maxMessageLength,proto3" json:"max_message_length,omitempty"`
 	MaxSubscriptions    int32  `protobuf:"varint,2,opt,name=max_subscriptions,json=maxSubscriptions,proto3" json:"max_subscriptions,omitempty"`
-	MaxFilters          int32  `protobuf:"varint,3,opt,name=max_filters,json=maxFilters,proto3" json:"max_filters,omitempty"`
 	MaxSubidLength      int32  `protobuf:"varint,4,opt,name=max_subid_length,json=maxSubidLength,proto3" json:"max_subid_length,omitempty"`
 	MinPowDifficulty    int32  `protobuf:"varint,5,opt,name=min_pow_difficulty,json=minPowDifficulty,proto3" json:"min_pow_difficulty,omitempty"`
 	AuthRequired        bool   `protobuf:"varint,6,opt,name=auth_required,json=authRequired,proto3" json:"auth_required,omitempty"`
@@ -87,13 +86,6 @@ func (x *Limitations) GetMaxSubscriptions() int32 {
 	return 0
 }
 
-func (x *Limitations) GetMaxFilters() int32 {
-	if x != nil {
-		return x.MaxFilters
-	}
-	return 0
-}
-
 func (x *Limitations) GetMaxSubidLength() int32 {
 	if x != nil {
 		return x.MaxSubidLength
@@ -268,65 +260,63 @@ var File_config_proto protoreflect.FileDescriptor
 
 var file_config_proto_rawDesc = []byte{
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+	0x0d, 0x20, 0x01, 0x28, 0x0d, 0x52, 0x11, 0x64, 0x65, 0x66, 0x61, 0x75, 0x6c, 0x74, 0x51, 0x75,
+	0x65, 0x72, 0x79, 0x4c, 0x69, 0x6d, 0x69, 0x74, 0x12, 0x26, 0x0a, 0x0f, 0x6d, 0x61, 0x78, 0x5f,
+	0x71, 0x75, 0x65, 0x72, 0x79, 0x5f, 0x6c, 0x69, 0x6d, 0x69, 0x74, 0x18, 0x0e, 0x20, 0x01, 0x28,
+	0x0d, 0x52, 0x0d, 0x6d, 0x61, 0x78, 0x51, 0x75, 0x65, 0x72, 0x79, 0x4c, 0x69, 0x6d, 0x69, 0x74,
+	0x22, 0x16, 0x0a, 0x14, 0x47, 0x65, 0x74, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72,
+	0x73, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x22, 0x64, 0x0a, 0x15, 0x47, 0x65, 0x74, 0x50,
+	0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e, 0x73,
+	0x65, 0x12, 0x39, 0x0a, 0x0b, 0x6c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73,
+	0x18, 0x01, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x17, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x72,
+	0x2e, 0x76, 0x31, 0x2e, 0x4c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73, 0x52,
+	0x0b, 0x6c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73, 0x12, 0x10, 0x0a, 0x03,
+	0x75, 0x72, 0x6c, 0x18, 0x02, 0x20, 0x01, 0x28, 0x09, 0x52, 0x03, 0x75, 0x72, 0x6c, 0x32, 0x62,
+	0x0a, 0x0a, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x12, 0x54, 0x0a, 0x0d,
+	0x47, 0x65, 0x74, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x12, 0x20, 0x2e,
+	0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x47, 0x65, 0x74, 0x50, 0x61,
+	0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74, 0x1a,
+	0x21, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x47, 0x65, 0x74,
 	0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x52, 0x65, 0x73, 0x70, 0x6f, 0x6e,
-	0x73, 0x65, 0x12, 0x39, 0x0a, 0x0b, 0x6c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e,
-	0x73, 0x18, 0x01, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x17, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65,
-	0x72, 0x2e, 0x76, 0x31, 0x2e, 0x4c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73,
-	0x52, 0x0b, 0x6c, 0x69, 0x6d, 0x69, 0x74, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x73, 0x12, 0x10, 0x0a,
-	0x03, 0x75, 0x72, 0x6c, 0x18, 0x02, 0x20, 0x01, 0x28, 0x09, 0x52, 0x03, 0x75, 0x72, 0x6c, 0x32,
-	0x62, 0x0a, 0x0a, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x12, 0x54, 0x0a,
-	0x0d, 0x47, 0x65, 0x74, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x12, 0x20,
-	0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x47, 0x65, 0x74, 0x50,
-	0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73, 0x74,
-	0x1a, 0x21, 0x2e, 0x6d, 0x61, 0x6e, 0x61, 0x67, 0x65, 0x72, 0x2e, 0x76, 0x31, 0x2e, 0x47, 0x65,
-	0x74, 0x50, 0x61, 0x72, 0x61, 0x6d, 0x65, 0x74, 0x65, 0x72, 0x73, 0x52, 0x65, 0x73, 0x70, 0x6f,
-	0x6e, 0x73, 0x65, 0x42, 0x3a, 0x5a, 0x38, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f,
-	0x6d, 0x2f, 0x64, 0x65, 0x7a, 0x68, 0x2d, 0x74, 0x65, 0x63, 0x68, 0x2f, 0x69, 0x6d, 0x6d, 0x6f,
-	0x72, 0x74, 0x61, 0x6c, 0x2f, 0x69, 0x6e, 0x66, 0x72, 0x61, 0x73, 0x74, 0x72, 0x75, 0x63, 0x74,
-	0x75, 0x72, 0x65, 0x2f, 0x67, 0x72, 0x70, 0x63, 0x5f, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x62,
-	0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+	0x73, 0x65, 0x42, 0x3a, 0x5a, 0x38, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d,
+	0x2f, 0x64, 0x65, 0x7a, 0x68, 0x2d, 0x74, 0x65, 0x63, 0x68, 0x2f, 0x69, 0x6d, 0x6d, 0x6f, 0x72,
+	0x74, 0x61, 0x6c, 0x2f, 0x69, 0x6e, 0x66, 0x72, 0x61, 0x73, 0x74, 0x72, 0x75, 0x63, 0x74, 0x75,
+	0x72, 0x65, 0x2f, 0x67, 0x72, 0x70, 0x63, 0x5f, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x62, 0x06,
+	0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
diff --git a/infrastructure/grpc_client/proto/config.proto b/infrastructure/grpc_client/proto/config.proto
index b361bc0..94122fb 100644
--- a/infrastructure/grpc_client/proto/config.proto
+++ b/infrastructure/grpc_client/proto/config.proto
@@ -10,8 +10,7 @@ service Parameters {
 
 message Limitations {
     int32 max_message_length = 1;        
-    int32 max_subscriptions = 2;          
-    int32 max_filters = 3;              
+    int32 max_subscriptions = 2;                    
     int32 max_subid_length = 4;        
     int32 min_pow_difficulty = 5;          
     bool auth_required = 6;              
diff --git a/makefile b/makefile
index 1c69bf7..abe3406 100644
--- a/makefile
+++ b/makefile
@@ -13,7 +13,6 @@ devtools:
 	go install mvdan.cc/gofumpt@latest
 	go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.35
 	go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.5
-	go install github.com/pactus-project/protoc-gen-doc/cmd/protoc-gen-doc@v0.0.0-20240815105130-84e89d0170e4
 	go install github.com/bufbuild/buf/cmd/buf@v1.47
 
 ### Testing
diff --git a/repository/delete.go b/repository/delete.go
index f0036bc..05bc449 100644
--- a/repository/delete.go
+++ b/repository/delete.go
@@ -5,23 +5,16 @@ import (
 
 	"github.com/dezh-tech/immortal/pkg/logger"
 	"github.com/dezh-tech/immortal/types"
+	"github.com/dezh-tech/immortal/types/filter"
 	"go.mongodb.org/mongo-driver/bson"
 )
 
 func (h *Handler) DeleteByID(id string, kind types.Kind) error {
-	coll := h.db.Client.Database(h.db.DBName).Collection(getCollectionName(kind))
-
-	ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
-	defer cancel()
-
-	filter := bson.D{
+	deleteFilter := bson.D{
 		{Key: "id", Value: id},
 	}
 
 	update := bson.D{
-		{Key: "$set", Value: bson.D{
-			{Key: "id", Value: id},
-		}},
 		{Key: "$unset", Value: bson.D{
 			{Key: "pubkey"},
 			{Key: "created_at"},
@@ -32,7 +25,13 @@ func (h *Handler) DeleteByID(id string, kind types.Kind) error {
 		}},
 	}
 
-	_, err := coll.UpdateOne(ctx, filter, update)
+	collName, _ := getCollectionName(kind)
+	coll := h.db.Client.Database(h.db.DBName).Collection(collName)
+
+	ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
+	defer cancel()
+
+	_, err := coll.UpdateOne(ctx, deleteFilter, update)
 	if err != nil {
 		_, err := h.grpc.AddLog(context.Background(),
 			"database error while removing event", err.Error())
@@ -45,3 +44,79 @@ func (h *Handler) DeleteByID(id string, kind types.Kind) error {
 
 	return nil
 }
+
+func (h *Handler) DeleteByFilter(f *filter.Filter) error {
+	// question/todo::: is it possible to run the deletion on all collections with one database call?
+	// we have an open issue on deletion execution.
+	// we do the read operation using aggregation pipeline and $unionWith stage which
+	// helps us ti prevent multiple database calls and it would help us to do the operation faster.
+	// to do the same thing for deletion we need to filter the documents with $match, then update the
+	// fields of deleted event to null (expect the `id` since its unique index to prevent overwrites) with $unset
+	// then we apply them to collection using $merge.
+	// although we can't use multiple $merge's on one pipeline and we must have
+	// only one merge at the end of pipeline commands. also, $unionWith is restricted to be used with $merge.
+
+	//  notes::: these details may help you to think for solutions better:
+	// 1. we create a collection for each kind or each group of kinds.
+	// using this model forces us to make query to all collections corresponding to provided kinds when
+	// we are dealing with filters since filters contain a list of kinds
+	// (which can be empty and we are then forced to query all collections)
+
+	// 2. when we delete an event we $unset all fields expect `id`.
+	// when we make a query to read from database, we ignore fields which
+	// their fields are null. and when we write new events we prevent overwriting
+	// events with duplicated `id`. so we can handle the deletion properly.
+
+	// resources::: these links may help you:
+	// 1. https://www.mongodb.com/docs/manual/reference/operator/aggregation/merge/#restrictions
+	// 2. https://www.mongodb.com/docs/manual/reference/operator/aggregation/unionWith/#mongodb-pipeline-pipe.-unionWith
+	// 3. https://www.mongodb.com/docs/manual/reference/operator/aggregation
+
+	queryKinds := make(map[types.Kind]*filter.Filter)
+
+	if len(f.Kinds) != 0 {
+		uniqueKinds := removeDuplicateKinds(f.Kinds)
+		for _, k := range uniqueKinds {
+			queryKinds[k] = f
+		}
+	} else {
+		for k := range types.KindToName {
+			queryKinds[k] = f
+		}
+	}
+
+	update := bson.D{
+		{Key: "$unset", Value: bson.D{
+			{Key: "pubkey"},
+			{Key: "created_at"},
+			{Key: "kind"},
+			{Key: "tags"},
+			{Key: "content"},
+			{Key: "sig"},
+		}},
+	}
+
+	for kind, deleteFilter := range queryKinds {
+		collectionName, isMultiKindColl := getCollectionName(kind)
+
+		query := filterToMongoQuery(deleteFilter, isMultiKindColl, kind)
+
+		ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
+
+		_, err := h.db.Client.Database(h.db.DBName).Collection(collectionName).UpdateMany(ctx, query, update)
+		if err != nil {
+			_, err := h.grpc.AddLog(ctx,
+				"database error while deleting events", err.Error())
+			if err != nil {
+				logger.Error("can't send log to manager", "err", err)
+			}
+
+			cancel()
+
+			return err
+		}
+		cancel()
+	}
+
+	return nil
+}
diff --git a/repository/event.go b/repository/event.go
index 6107ee2..2f8eba8 100644
--- a/repository/event.go
+++ b/repository/event.go
@@ -11,7 +11,8 @@ import (
 )
 
 func (h *Handler) HandleEvent(e *event.Event) error {
-	coll := h.db.Client.Database(h.db.DBName).Collection(getCollectionName(e.Kind))
+	collName, _ := getCollectionName(e.Kind)
+	coll := h.db.Client.Database(h.db.DBName).Collection(collName)
 
 	ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
 	defer cancel()
diff --git a/repository/handler.go b/repository/handler.go
index 879618b..cb84ebd 100644
--- a/repository/handler.go
+++ b/repository/handler.go
@@ -4,6 +4,8 @@ import (
 	"github.com/dezh-tech/immortal/infrastructure/database"
 	grpcclient "github.com/dezh-tech/immortal/infrastructure/grpc_client"
 	"github.com/dezh-tech/immortal/types"
+	"github.com/dezh-tech/immortal/types/filter"
+	"go.mongodb.org/mongo-driver/bson"
 )
 
 type Handler struct {
@@ -20,27 +22,86 @@ func New(cfg Config, db *database.Database, grpc grpcclient.IClient) *Handler {
 	}
 }
 
-func getCollectionName(k types.Kind) string {
+func filterToMongoQuery(f *filter.Filter, isMultiKindColl bool, k types.Kind) bson.D {
+	query := make(bson.D, 0)
+
+	if isMultiKindColl {
+		query = append(query, bson.E{Key: "kind", Value: k})
+	}
+
+	query = append(query, bson.E{Key: "pubkey", Value: bson.M{
+		"$exists": true,
+	}})
+
+	if len(f.IDs) > 0 {
+		query = append(query, bson.E{Key: "id", Value: bson.M{"$in": f.IDs}})
+	}
+
+	if len(f.Authors) > 0 {
+		query = append(query, bson.E{Key: "pubkey", Value: bson.M{"$in": f.Authors}})
+	}
+
+	if len(f.Tags) > 0 {
+		tagQueries := bson.A{}
+		for tagKey, tagValues := range f.Tags {
+			qtf := bson.M{
+				"tags": bson.M{
+					"$elemMatch": bson.M{
+						"0": tagKey,
+						"1": bson.M{"$in": tagValues},
+					},
+				},
+			}
+			tagQueries = append(tagQueries, qtf)
+		}
+		query = append(query, bson.E{Key: "$and", Value: tagQueries})
+	}
+
+	if f.Since > 0 {
+		query = append(query, bson.E{Key: "created_at", Value: bson.M{"$gte": f.Since}})
+	}
+
+	if f.Until > 0 {
+		query = append(query, bson.E{Key: "created_at", Value: bson.M{"$lte": f.Until}})
+	}
+
+	return query
+}
+
+func getCollectionName(k types.Kind) (string, bool) {
 	collName, ok := types.KindToName[k]
 	if ok {
-		return collName
+		return collName, false
 	}
 
 	if k >= 9000 && k <= 9030 {
-		return "groups"
+		return "groups", true
 	}
 
 	if k >= 1630 && k <= 1633 {
-		return "status"
+		return "status", true
 	}
 
 	if k >= 39000 && k <= 39009 {
-		return "groups_metadata"
+		return "groups_metadata", true
 	}
 
 	if k >= 5000 && k <= 5999 || k >= 6000 && k <= 6999 || k == 7000 {
-		return "dvm"
+		return "dvm", true
+	}
+
+	return "unknown", true
+}
+
+func removeDuplicateKinds(intSlice []types.Kind) []types.Kind {
+	allKeys := make(map[types.Kind]bool, len(intSlice))
+	list := []types.Kind{}
+	for _, item := range intSlice {
+		if _, value := allKeys[item]; !value {
+			allKeys[item] = true
+			list = append(list, item)
+		}
 	}
 
-	return "unknown"
+	return list
 }
diff --git a/repository/req.go b/repository/req.go
index 2cf25a6..bc8b88d 100644
--- a/repository/req.go
+++ b/repository/req.go
@@ -2,7 +2,6 @@ package repository
 
 import (
 	"context"
-	"errors"
 
 	"github.com/dezh-tech/immortal/pkg/logger"
 	"github.com/dezh-tech/immortal/types"
@@ -10,156 +9,90 @@ import (
 	"github.com/dezh-tech/immortal/types/filter"
 	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/mongo"
-	"go.mongodb.org/mongo-driver/mongo/options"
 )
 
-var possibleKinds = []types.Kind{
-	types.KindUserMetadata,
-	types.KindShortTextNote,
-	types.KindZap,
-	types.KindRelayListMetadata,
-}
-
-type filterQuery struct {
-	Tags map[string][]string
+func (h *Handler) HandleReq(f *filter.Filter) ([]event.Event, error) {
+	queryKinds := make(map[types.Kind]*filter.Filter)
 
-	Authors []string
-	IDs     []string
+	if len(f.Kinds) != 0 {
+		uniqueKinds := removeDuplicateKinds(f.Kinds)
+		for _, k := range uniqueKinds {
+			queryKinds[k] = f
+		}
+	} else {
+		for k := range types.KindToName {
+			queryKinds[k] = f
+		}
+	}
 
-	Since int64
-	Until int64
-	Limit uint32
-}
+	var pipeline mongo.Pipeline
 
-func (h *Handler) HandleReq(fs filter.Filters) ([]event.Event, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
-	defer cancel()
+	for kind, filter := range queryKinds {
+		collectionName, isMultiKindColl := getCollectionName(kind)
 
-	queryKinds := make(map[types.Kind][]filterQuery)
+		query := filterToMongoQuery(filter, isMultiKindColl, kind)
 
-	for _, f := range fs {
-		qf := filterQuery{
-			Tags:    f.Tags,
-			Authors: f.Authors,
-			IDs:     f.IDs,
-			Since:   f.Since,
-			Until:   f.Until,
-			Limit:   f.Limit,
+		matchStage := bson.D{
+			{Key: "$match", Value: query},
 		}
 
-		if len(f.Kinds) != 0 {
-			uniqueKinds := removeDuplicateKind(f.Kinds)
-			for _, k := range uniqueKinds {
-				queryKinds[k] = append(queryKinds[k], qf)
-			}
-		} else {
-			// ! it makes query to the most requested kinds if there is no kind provided.
-			// ? fix::: any better way?
-			for _, k := range possibleKinds {
-				queryKinds[k] = append(queryKinds[k], qf)
-			}
+		unionStage := bson.D{
+			{Key: "$unionWith", Value: bson.D{
+				{Key: "coll", Value: collectionName},
+				{Key: "pipeline", Value: mongo.Pipeline{
+					matchStage,
+				}},
+			}},
 		}
-	}
-
-	var finalResult []event.Event
 
-	for kind, filters := range queryKinds {
-		// todo::: querying database in goroutines.
-		collection := h.db.Client.Database(h.db.DBName).Collection(getCollectionName(kind))
-		for _, f := range filters {
-			query, opts, err := h.FilterToQuery(&f)
-			if err != nil {
-				continue
-			}
-
-			cursor, err := collection.Find(ctx, query, opts)
-			if err != nil {
-				if !errors.Is(err, mongo.ErrNoDocuments) {
-					_, err := h.grpc.AddLog(context.Background(),
-						"database error while making query", err.Error())
-					if err != nil {
-						logger.Error("can't send log to manager", "err", err)
-					}
-				}
-
-				return nil, err
-			}
-
-			var result []event.Event
-			if err := cursor.All(ctx, &result); err != nil {
-				return nil, err
-			}
-
-			finalResult = append(finalResult, result...)
-		}
+		pipeline = append(pipeline, unionStage)
 	}
 
-	return finalResult, nil
-}
-
-func removeDuplicateKind(intSlice []types.Kind) []types.Kind {
-	allKeys := make(map[types.Kind]bool)
-	list := []types.Kind{}
-	for _, item := range intSlice {
-		if _, value := allKeys[item]; !value {
-			allKeys[item] = true
-			list = append(list, item)
-		}
+	sortStage := bson.D{
+		{Key: "$sort", Value: bson.D{
+			{Key: "created_at", Value: -1},
+			{Key: "id", Value: 1},
+		}},
 	}
 
-	return list
-}
-
-func (h *Handler) FilterToQuery(fq *filterQuery) (bson.D, *options.FindOptions, error) {
-	query := make(bson.D, 0)
-	opts := options.Find()
-
-	query = append(query, bson.E{Key: "pubkey", Value: bson.M{
-		"$exists": true,
-	}})
+	pipeline = append(pipeline, sortStage)
 
-	if len(fq.IDs) > 0 {
-		query = append(query, bson.E{Key: "id", Value: bson.M{"$in": fq.IDs}})
+	finalLimit := h.config.DefaultQueryLimit
+	if f.Limit > 0 && f.Limit < h.config.MaxQueryLimit {
+		finalLimit = f.Limit
 	}
 
-	if len(fq.Authors) > 0 {
-		query = append(query, bson.E{Key: "pubkey", Value: bson.M{"$in": fq.Authors}})
+	limitStage := bson.D{
+		{Key: "$limit", Value: finalLimit},
 	}
 
-	if len(fq.Tags) > 0 {
-		tagQueries := bson.A{}
-		for tagKey, tagValues := range fq.Tags {
-			qtf := bson.M{
-				"tags": bson.M{
-					"$elemMatch": bson.M{
-						"0": tagKey,
-						"1": bson.M{"$in": tagValues},
-					},
-				},
-			}
-			tagQueries = append(tagQueries, qtf)
+	pipeline = append(pipeline, limitStage)
+
+	ctx, cancel := context.WithTimeout(context.Background(), h.db.QueryTimeout)
+	defer cancel()
+
+	cursor, err := h.db.Client.Database(h.db.DBName).Collection("empty").Aggregate(ctx, pipeline)
+	if err != nil {
+		_, err := h.grpc.AddLog(context.Background(),
+			"database error while adding new event", err.Error())
+		if err != nil {
+			logger.Error("can't send log to manager", "err", err)
 		}
-		query = append(query, bson.E{Key: "$and", Value: tagQueries})
-	}
 
-	if fq.Since > 0 {
-		query = append(query, bson.E{Key: "created_at", Value: bson.M{"$gte": fq.Since}})
+		return nil, err
 	}
+	defer cursor.Close(ctx)
 
-	if fq.Until > 0 {
-		query = append(query, bson.E{Key: "created_at", Value: bson.M{"$lte": fq.Since}})
-	}
+	var finalResult []event.Event
+	if err := cursor.All(ctx, &finalResult); err != nil {
+		_, err := h.grpc.AddLog(context.Background(),
+			"database error while adding new event", err.Error())
+		if err != nil {
+			logger.Error("can't send log to manager", "err", err)
+		}
 
-	if fq.Limit > 0 && fq.Limit < h.config.MaxQueryLimit {
-		opts.SetLimit(int64(fq.Limit))
-	} else {
-		opts.SetLimit(int64(h.config.DefaultQueryLimit))
+		return nil, err
 	}
 
-	opts.SetSort(bson.D{
-		{Key: "created_at", Value: -1},
-		{Key: "id", Value: 1},
-	})
-
-	return query, opts, nil
+	return finalResult, nil
 }
diff --git a/types/event/event.go b/types/event/event.go
index a8ef76b..9efed9e 100644
--- a/types/event/event.go
+++ b/types/event/event.go
@@ -99,14 +99,14 @@ func (e *Event) IsValid(id [32]byte) bool {
 		return false
 	}
 
-	// TODO::: replace with libsecp256k1 (C++ version).
+	// todo::: replace with libsecp256k1 (C++ version).
 	return sig.Verify(id[:], pubkey)
 }
 
-// IsProtected checks is ["-"] is present, look nip-70 for more.
+// IsProtected checks if ["-"] tag is present, check nip-70 for more.
 func (e *Event) IsProtected() bool {
 	for _, t := range e.Tags {
-		if len(t) < 1 {
+		if len(t) != 1 {
 			continue
 		}
 
diff --git a/types/message/message.go b/types/message/message.go
index e78a7c5..f18ddfc 100644
--- a/types/message/message.go
+++ b/types/message/message.go
@@ -126,7 +126,7 @@ func (em Event) EncodeToJSON() ([]byte, error) {
 // Req represents a NIP-01 REQ message.
 type Req struct {
 	SubscriptionID string
-	filter.Filters
+	filter.Filter
 }
 
 func (Req) Type() string { return "REQ" }
@@ -140,21 +140,17 @@ func (rm *Req) DecodeFromJSON(data []byte) error {
 		}
 	}
 	rm.SubscriptionID = arr[1].Str
-	rm.Filters = make(filter.Filters, len(arr)-2)
-	f := 0
-	for i := 2; i < len(arr); i++ {
-		if err := easyjson.Unmarshal([]byte(arr[i].Raw), &rm.Filters[f]); err != nil {
-			return types.DecodeError{
-				Reason: fmt.Sprintf("REQ message: %s", err.Error()),
-			}
+	rm.Filter = filter.Filter{}
+	if err := easyjson.Unmarshal([]byte(arr[2].Raw), &rm.Filter); err != nil {
+		return types.DecodeError{
+			Reason: fmt.Sprintf("REQ message: %s", err.Error()),
 		}
-		f++
 	}
 
 	return nil
 }
 
-func (rm Req) EncodeToJSON() ([]byte, error) {
+func (rm *Req) EncodeToJSON() ([]byte, error) {
 	return nil, nil
 }
 
diff --git a/types/message/message_test.go b/types/message/message_test.go
index e05d43a..eee371b 100644
--- a/types/message/message_test.go
+++ b/types/message/message_test.go
@@ -34,13 +34,13 @@ var testCases = []testCase{
 	},
 	{
 		Name:    "REQ message",
-		Message: []byte(`["REQ","million", {"kinds": [1]}, {"kinds": [30023 ], "#d": ["buteko",    "batuke"]}]`),
+		Message: []byte(`["REQ","million", {"kinds": [30023 ], "#d": ["buteko",    "batuke"]}]`),
 		ExpectedEnvelope: &message.Req{
 			SubscriptionID: "million",
-			Filters: filter.Filters{{Kinds: []types.Kind{1}}, {
+			Filter: filter.Filter{
 				Kinds: []types.Kind{30023},
 				Tags:  map[string][]string{"d": {"buteko", "batuke"}},
-			}},
+			},
 		},
 	},
 	{