diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c8111ca..9a512024 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ### Builds after release 0.12.0
 
+#### Build 2106170
+
+-   Optimized JSON buffer usage (pre-serialized color arrays)
+
 #### Build 2106140
 
 -   Updated main logo
diff --git a/wled00/json.cpp b/wled00/json.cpp
index 444cf52a..85da62ae 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -330,24 +330,38 @@ void serializeSegment(JsonObject& root, WS2812FX::Segment& seg, byte id, bool fo
 
 	JsonArray colarr = root.createNestedArray("col");
 
+  char colstr[70]; //max len 68 (5 chan, all 255)
+  obuf = colstr; olen = 0;
+  oappend("[");
+
 	for (uint8_t i = 0; i < 3; i++)
 	{
-		JsonArray colX = colarr.createNestedArray();
+    oappend("[");
+
     if (id == strip.getMainSegmentId() && i < 2) //temporary, to make transition work on main segment
     {
-      if (i == 0) {
-        colX.add(col[0]); colX.add(col[1]); colX.add(col[2]); if (strip.isRgbw) colX.add(col[3]);
-      } else {
-         colX.add(colSec[0]); colX.add(colSec[1]); colX.add(colSec[2]); if (strip.isRgbw) colX.add(colSec[3]);
+      byte* c = (i == 0)? col:colSec;
+
+      oappendi(c[0]); oappend(",");
+      oappendi(c[1]); oappend(",");
+      oappendi(c[2]);
+      if (strip.isRgbw) {
+        oappend(","); oappendi(c[3]);
       }
     } else {
-  		colX.add((seg.colors[i] >> 16) & 0xFF);
-  		colX.add((seg.colors[i] >> 8) & 0xFF);
-  		colX.add((seg.colors[i]) & 0xFF);
-  		if (strip.isRgbw)
-  			colX.add((seg.colors[i] >> 24) & 0xFF);
+  		oappendi((seg.colors[i] >> 16) & 0xFF); oappend(",");
+  		oappendi((seg.colors[i] >> 8) & 0xFF); oappend(",");
+  		oappendi((seg.colors[i]) & 0xFF);
+  		if (strip.isRgbw) {
+  			oappend(","); oappendi((seg.colors[i] >> 24) & 0xFF);
+      }
     }
+
+    oappend("]");
+    if (i < 2) oappend(",");
 	}
+  oappend("]");
+  root["col"] = serialized(colstr);
 
 	root[F("fx")]  = seg.mode;
 	root[F("sx")]  = seg.speed;
@@ -790,6 +804,9 @@ void serveJson(AsyncWebServerRequest* request)
       }
   }
 
+  DEBUG_PRINT("JSON buffer size: ");
+  DEBUG_PRINTLN(doc.memoryUsage());
+
   response->setLength();
   request->send(response);
 }
diff --git a/wled00/wled.h b/wled00/wled.h
index 8ce5a7b3..51bd81f7 100644
--- a/wled00/wled.h
+++ b/wled00/wled.h
@@ -8,7 +8,7 @@
  */
 
 // version code in format yymmddb (b = daily build)
-#define VERSION 2106140
+#define VERSION 2106170
 
 //uncomment this if you have a "my_config.h" file you'd like to use
 //#define WLED_USE_MY_CONFIG