diff --git a/kilo-client/src/main/java/org/httprpc/kilo/io/CSVEncoder.java b/kilo-client/src/main/java/org/httprpc/kilo/io/CSVEncoder.java
index 9384bf1d6..ea2f78d5d 100644
--- a/kilo-client/src/main/java/org/httprpc/kilo/io/CSVEncoder.java
+++ b/kilo-client/src/main/java/org/httprpc/kilo/io/CSVEncoder.java
@@ -162,25 +162,35 @@ private void encode(Iterable<? extends Map<String, ?>> records, Writer writer) t
 
     private void encode(Object value, Writer writer) throws IOException {
         if (value == null) {
-            writer.write("");
-        } else if (value instanceof CharSequence text) {
-            writer.write('"');
-
-            for (int i = 0, n = text.length(); i < n; i++) {
-                var c = text.charAt(i);
-
-                if (c == '"') {
-                    writer.append("\"\"");
-                } else {
-                    writer.append(c);
-                }
-            }
+            return;
+        }
 
-            writer.write('"');
+        if (value instanceof CharSequence text) {
+            encode(text, writer);
         } else if (value instanceof Date date) {
-            writer.write(String.valueOf(date.getTime()));
+            encode(date, writer);
         } else {
             writer.write(value.toString());
         }
     }
+
+    private void encode(CharSequence text, Writer writer) throws IOException {
+        writer.write('"');
+
+        for (int i = 0, n = text.length(); i < n; i++) {
+            var c = text.charAt(i);
+
+            if (c == '"') {
+                writer.append("\"\"");
+            } else {
+                writer.append(c);
+            }
+        }
+
+        writer.write('"');
+    }
+
+    private void encode(Date date, Writer writer) throws IOException {
+        writer.write(String.valueOf(date.getTime()));
+    }
 }
diff --git a/kilo-client/src/main/java/org/httprpc/kilo/io/JSONEncoder.java b/kilo-client/src/main/java/org/httprpc/kilo/io/JSONEncoder.java
index 21fbacf8f..46923cc26 100644
--- a/kilo-client/src/main/java/org/httprpc/kilo/io/JSONEncoder.java
+++ b/kilo-client/src/main/java/org/httprpc/kilo/io/JSONEncoder.java
@@ -64,71 +64,85 @@ private void encode(Object value, Writer writer) throws IOException {
         if (value == null) {
             writer.append(null);
         } else if (value instanceof CharSequence text) {
-            writer.write("\"");
-
-            for (int i = 0, n = text.length(); i < n; i++) {
-                var c = text.charAt(i);
-
-                if (c == '"' || c == '\\') {
-                    writer.write("\\" + c);
-                } else if (c == '\b') {
-                    writer.write("\\b");
-                } else if (c == '\f') {
-                    writer.write("\\f");
-                } else if (c == '\n') {
-                    writer.write("\\n");
-                } else if (c == '\r') {
-                    writer.write("\\r");
-                } else if (c == '\t') {
-                    writer.write("\\t");
-                } else if (Character.isISOControl(c)) {
-                    writer.write(String.format("\\u%04x", (int)c));
-                } else {
-                    writer.write(c);
-                }
-            }
-
-            writer.write("\"");
+            encode(text, writer);
         } else if (value instanceof Float number) {
             if (number.isNaN() || number.isInfinite()) {
                 throw new IllegalArgumentException("Invalid float value.");
             }
 
-            writer.write(value.toString());
+            encode(number, writer);
         } else if (value instanceof Double number) {
             if (number.isNaN() || number.isInfinite()) {
                 throw new IllegalArgumentException("Invalid double value.");
             }
 
-            writer.write(value.toString());
-        } else if (value instanceof Number || value instanceof Boolean) {
-            writer.write(value.toString());
+            encode(number, writer);
+        } else if (value instanceof Number number) {
+            encode(number, writer);
         } else if (value instanceof Date date) {
-            writer.write(String.valueOf(date.getTime()));
+            encode(date, writer);
+        } else if (value instanceof Boolean flag) {
+            encode(flag, writer);
         } else if (value instanceof Iterable<?> iterable) {
-            writer.write("[");
+            encode(iterable, writer);
+        } else if (value instanceof Map<?, ?> map) {
+            encode(map, writer);
+        } else {
+            encode(value.toString(), writer);
+        }
+    }
+
+    private void encode(CharSequence text, Writer writer) throws IOException {
+        writer.write("\"");
+
+        for (int i = 0, n = text.length(); i < n; i++) {
+            var c = text.charAt(i);
+
+            if (c == '"' || c == '\\') {
+                writer.write("\\" + c);
+            } else if (c == '\b') {
+                writer.write("\\b");
+            } else if (c == '\f') {
+                writer.write("\\f");
+            } else if (c == '\n') {
+                writer.write("\\n");
+            } else if (c == '\r') {
+                writer.write("\\r");
+            } else if (c == '\t') {
+                writer.write("\\t");
+            } else if (Character.isISOControl(c)) {
+                writer.write(String.format("\\u%04x", (int)c));
+            } else {
+                writer.write(c);
+            }
+        }
 
-            depth++;
+        writer.write("\"");
+    }
 
-            var i = 0;
+    private void encode(Number number, Writer writer) throws IOException {
+        writer.write(number.toString());
+    }
 
-            for (var element : iterable) {
-                if (i > 0) {
-                    writer.write(",");
-                }
+    private void encode(Date date, Writer writer) throws IOException {
+        writer.write(String.valueOf(date.getTime()));
+    }
 
-                if (!compact) {
-                    writer.write("\n");
+    private void encode(Boolean flag, Writer writer) throws IOException {
+        writer.write(flag.toString());
+    }
 
-                    indent(writer);
-                }
+    private void encode(Iterable<?> iterable, Writer writer) throws IOException {
+        writer.write("[");
 
-                encode(element, writer);
+        depth++;
 
-                i++;
-            }
+        var i = 0;
 
-            depth--;
+        for (var element : iterable) {
+            if (i > 0) {
+                writer.write(",");
+            }
 
             if (!compact) {
                 writer.write("\n");
@@ -136,45 +150,39 @@ private void encode(Object value, Writer writer) throws IOException {
                 indent(writer);
             }
 
-            writer.write("]");
-        } else if (value instanceof Map<?, ?> map) {
-            writer.write("{");
-
-            depth++;
+            encode(element, writer);
 
-            var i = 0;
-
-            for (var entry : map.entrySet()) {
-                var key = entry.getKey();
+            i++;
+        }
 
-                if (!(key instanceof String)) {
-                    throw new IllegalArgumentException("Invalid key.");
-                }
+        depth--;
 
-                if (i > 0) {
-                    writer.write(",");
-                }
+        if (!compact) {
+            writer.write("\n");
 
-                if (!compact) {
-                    writer.write("\n");
+            indent(writer);
+        }
 
-                    indent(writer);
-                }
+        writer.write("]");
+    }
 
-                encode(key, writer);
+    private void encode(Map<?, ?> map, Writer writer) throws IOException {
+        writer.write("{");
 
-                writer.write(":");
+        depth++;
 
-                if (!compact) {
-                    writer.write(" ");
-                }
+        var i = 0;
 
-                encode(entry.getValue(), writer);
+        for (var entry : map.entrySet()) {
+            var key = entry.getKey();
 
-                i++;
+            if (!(key instanceof String)) {
+                throw new IllegalArgumentException("Invalid key.");
             }
 
-            depth--;
+            if (i > 0) {
+                writer.write(",");
+            }
 
             if (!compact) {
                 writer.write("\n");
@@ -182,10 +190,28 @@ private void encode(Object value, Writer writer) throws IOException {
                 indent(writer);
             }
 
-            writer.write("}");
-        } else {
-            encode(value.toString(), writer);
+            encode(key, writer);
+
+            writer.write(":");
+
+            if (!compact) {
+                writer.write(" ");
+            }
+
+            encode(entry.getValue(), writer);
+
+            i++;
         }
+
+        depth--;
+
+        if (!compact) {
+            writer.write("\n");
+
+            indent(writer);
+        }
+
+        writer.write("}");
     }
 
     private void indent(Writer writer) throws IOException {