diff --git a/koinos/koindx_tracker/koindx_tracker.proto b/koinos/koindx_tracker/koindx_tracker.proto
new file mode 100644
index 0000000..6995649
--- /dev/null
+++ b/koinos/koindx_tracker/koindx_tracker.proto
@@ -0,0 +1,28 @@
+syntax = "proto3";
+
+package koinos.koindx_tracker;
+option go_package = "github.com/koinos/koinos-proto-golang/v2/koinos/koindx_tracker";
+
+import "koinos/options.proto";
+
+message liquidity_record {
+   bytes address = 1 [(btype) = ADDRESS];
+   uint64 balance = 2 [jstype = JS_STRING];
+   uint64 prev_coin_ms_hi = 3 [jstype = JS_STRING];
+   uint64 prev_coin_ms_lo = 4 [jstype = JS_STRING];
+   uint64 last_update = 5 [jstype = JS_STRING];
+}
+
+message tvl_record {
+   uint64 value = 1 [jstype = JS_STRING];
+}
+
+message initialize_event {
+   string token_a = 1;
+   string token_b = 2;
+}
+
+message sync_event {
+   uint64 reserve_a = 1 [jstype = JS_STRING];
+   uint64 reserve_b = 2 [jstype = JS_STRING];
+}
diff --git a/koinos/rpc/koindx_tracker/koindx_tracker_rpc.proto b/koinos/rpc/koindx_tracker/koindx_tracker_rpc.proto
new file mode 100644
index 0000000..209a485
--- /dev/null
+++ b/koinos/rpc/koindx_tracker/koindx_tracker_rpc.proto
@@ -0,0 +1,83 @@
+syntax = "proto3";
+
+package koinos.rpc.koindx_tracker;
+option go_package = "github.com/koinos/koinos-proto-golang/v2/koinos/rpc/koindx_tracker";
+
+import "koinos/koindx_tracker/koindx_tracker.proto";
+import "koinos/options.proto";
+import "koinos/rpc/rpc.proto";
+
+message pool_pair {
+   bytes pool = 1 [(btype) = ADDRESS];
+   string token_a = 2;
+   string token_b = 3;
+}
+
+message get_pools_request {
+   oneof target {
+      bytes start = 1 [(btype) = ADDRESS];
+      bytes pool = 2 [(btype) = ADDRESS];
+   }
+   uint64 limit = 3 [jstype = JS_STRING];
+}
+
+message get_pools_response {
+   repeated pool_pair values = 1;
+}
+
+message account_liquidity {
+   bytes address = 1 [(btype) = ADDRESS];
+   uint64 balance = 2 [jstype = JS_STRING];
+   uint64 coin_ms_hi = 3 [jstype = JS_STRING];
+   uint64 coin_ms_lo = 4 [jstype = JS_STRING];
+}
+
+message get_liquidity_request {
+   bytes pool = 1 [(btype) = ADDRESS];
+   bytes start = 2 [(btype) = ADDRESS];
+   uint64 limit = 3 [jstype = JS_STRING];
+   optional uint64 start_ms = 4 [jstype = JS_STRING];
+   optional uint64 end_ms = 5 [jstype = JS_STRING];
+}
+
+message get_liquidity_response {
+   repeated account_liquidity values = 1;
+}
+
+message pool_tvl {
+   bytes pool = 1 [(btype) = ADDRESS];
+   uint64 tvl = 2 [jstype = JS_STRING];
+}
+
+message get_tvl_request {
+   oneof target {
+      bytes start = 1 [(btype) = ADDRESS];
+      bytes pool = 2 [(btype) = ADDRESS];
+   }
+
+   uint64 limit = 3 [jstype = JS_STRING];
+   optional uint64 ms = 4 [jstype = JS_STRING];
+}
+
+message get_tvl_response {
+   repeated pool_tvl values = 1;
+}
+
+message koindx_tracker_request {
+   oneof request {
+      rpc.reserved_rpc reserved = 1;
+      get_pools_request get_pools = 2;
+      get_liquidity_request get_liquidity = 3;
+      get_tvl_request get_tvl = 4;
+   }
+}
+
+message koindx_tracker_response {
+   oneof response {
+      rpc.reserved_rpc reserved = 1;
+      rpc.error_status error = 2;
+      get_pools_response get_pools = 3;
+      get_liquidity_response get_liquidity = 4;
+      get_tvl_response get_tvl = 5;
+   }
+}
diff --git a/koinos/standards/kcs4.proto b/koinos/standards/kcs4.proto
index a0d0d4c..c908a88 100644
--- a/koinos/standards/kcs4.proto
+++ b/koinos/standards/kcs4.proto
@@ -75,7 +75,7 @@ message transfer_arguments {
    bytes from = 1 [(btype) = ADDRESS];
    bytes to = 2 [(btype) = ADDRESS];
    uint64 value = 3 [jstype = JS_STRING];
-   string memo = 4;
+   optional string memo = 4;
 }
 
 message transfer_result {}
@@ -83,6 +83,7 @@ message transfer_result {}
 message mint_arguments {
    bytes to = 1 [(btype) = ADDRESS];
    uint64 value = 2 [jstype = JS_STRING];
+   optional string memo = 3;
 }
 
 message mint_result {}
@@ -90,6 +91,7 @@ message mint_result {}
 message burn_arguments {
    bytes from = 1 [(btype) = ADDRESS];
    uint64 value = 2 [jstype = JS_STRING];
+   optional string memo = 3;
 }
 
 message burn_result {}
@@ -98,6 +100,7 @@ message approve_arguments {
    bytes owner = 1 [(koinos.btype) = ADDRESS];
    bytes spender = 2 [(koinos.btype) = ADDRESS];
    uint64 value = 3 [jstype = JS_STRING];
+   optional string memo = 4;
 }
 
 message approve_result {}
@@ -105,22 +108,25 @@ message approve_result {}
 message burn_event {
    bytes from = 1 [(btype) = ADDRESS];
    uint64 value = 2 [jstype = JS_STRING];
+   optional string memo = 3;
 }
 
 message mint_event {
    bytes to = 1 [(btype) = ADDRESS];
    uint64 value = 2 [jstype = JS_STRING];
+   optional string memo = 3;
 }
 
 message transfer_event {
    bytes from = 1 [(btype) = ADDRESS];
    bytes to = 2 [(btype) = ADDRESS];
    uint64 value = 3 [jstype = JS_STRING];
-   string memo = 4;
+   optional string memo = 4;
 }
 
 message approve_event {
    bytes owner = 1 [(koinos.btype) = ADDRESS];
    bytes spender = 2 [(koinos.btype) = ADDRESS];
    uint64 value = 3 [jstype = JS_STRING];
+   optional string memo = 4;
 }