diff --git a/include/weaseljson.h b/include/weaseljson.h
index cafce4a..54ab0cb 100644
--- a/include/weaseljson.h
+++ b/include/weaseljson.h
@@ -13,6 +13,11 @@ struct WeaselJsonCallbacks {
    * incomplete and there will be another call, potentially with more data
    */
   void (*on_string_data)(void *userdata, const char *buf, int len, int done);
+  /** The key data provided has already been unescaped, unless the
+   * WeaselJsonRaw flag is used. If `done` is false, this key may be
+   * incomplete and there will be another call, potentially with more data
+   */
+  void (*on_key_data)(void *userdata, const char *buf, int len, int done);
   void (*on_begin_array)(void *userdata);
   void (*on_end_array)(void *userdata);
   /*If `done` is false, this number may be incomplete and there will be another
diff --git a/src/callbacks.h b/src/callbacks.h
index cb9cd34..b6bb39f 100644
--- a/src/callbacks.h
+++ b/src/callbacks.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cassert>
 #include <cstdint>
 #include <cstdio>
 #include <string>
@@ -14,6 +15,9 @@ inline WeaselJsonCallbacks printCallbacks() {
   result.on_string_data = +[](void *, const char *buf, int len, int /*done*/) {
     printf("on_string_data `%.*s`\n", len, buf);
   };
+  result.on_key_data = +[](void *, const char *buf, int len, int /*done*/) {
+    printf("on_key_data `%.*s`\n", len, buf);
+  };
   result.on_begin_array = +[](void *) { puts("on_begin_array"); };
   result.on_end_array = +[](void *) { puts("on_end_array"); };
   result.on_number_data = +[](void *, const char *buf, int len, int /*done*/) {
@@ -30,6 +34,7 @@ inline WeaselJsonCallbacks noopCallbacks() {
   result.on_begin_object = +[](void *) {};
   result.on_end_object = +[](void *) {};
   result.on_string_data = +[](void *, const char *, int, int) {};
+  result.on_key_data = +[](void *, const char *, int, int) {};
   result.on_begin_array = +[](void *) {};
   result.on_end_array = +[](void *) {};
   result.on_number_data = +[](void *, const char *, int, int) {};
@@ -58,6 +63,11 @@ struct SerializeState {
       if (!back.isObject && back.index > 0) {
         result.append(",");
       }
+    }
+  }
+  void on_end_value() {
+    if (!stack.empty()) {
+      auto &back = stack.back();
       ++back.index;
     }
   }
@@ -77,6 +87,7 @@ inline WeaselJsonCallbacks serializeCallbacks() {
     auto *state = (SerializeState *)p;
     state->stack.pop_back();
     state->result.append("}");
+    state->on_end_value();
   };
   result.on_string_data = +[](void *p, const char *buf, int len, int done) {
     auto *state = (SerializeState *)p;
@@ -86,7 +97,28 @@ inline WeaselJsonCallbacks serializeCallbacks() {
       state->result.append("<");
     }
     state->result.append(std::string(buf, len));
+    if (!state->stack.empty() && state->stack.back().isObject) {
+      assert(state->stack.back().index % 2 == 1);
+    }
     if (done) {
+      state->on_end_value();
+      state->startedData = false;
+      state->result.append(">");
+    }
+  };
+  result.on_key_data = +[](void *p, const char *buf, int len, int done) {
+    auto *state = (SerializeState *)p;
+    if (!state->startedData) {
+      state->startedData = true;
+      state->on_begin_value();
+      state->result.append("<");
+    }
+    state->result.append(std::string(buf, len));
+    assert(!state->stack.empty());
+    assert(state->stack.back().isObject);
+    assert(state->stack.back().index % 2 == 0);
+    if (done) {
+      state->on_end_value();
       state->startedData = false;
       state->result.append(">");
     }
@@ -101,6 +133,7 @@ inline WeaselJsonCallbacks serializeCallbacks() {
     auto *state = (SerializeState *)p;
     state->stack.pop_back();
     state->result.append("]");
+    state->on_end_value();
   };
   result.on_number_data = +[](void *p, const char *buf, int len, int done) {
     auto *state = (SerializeState *)p;
@@ -112,6 +145,7 @@ inline WeaselJsonCallbacks serializeCallbacks() {
     state->result.append(std::string(buf, len));
     if (done) {
       state->startedData = false;
+      state->on_end_value();
       state->result.append(")");
     }
   };
@@ -119,16 +153,19 @@ inline WeaselJsonCallbacks serializeCallbacks() {
     auto *state = (SerializeState *)p;
     state->on_begin_value();
     state->result.append("true");
+    state->on_end_value();
   };
   result.on_false_literal = +[](void *p) {
     auto *state = (SerializeState *)p;
     state->on_begin_value();
     state->result.append("false");
+    state->on_end_value();
   };
   result.on_null_literal = +[](void *p) {
     auto *state = (SerializeState *)p;
     state->on_begin_value();
     state->result.append("null");
+    state->on_end_value();
   };
   return result;
 }
diff --git a/src/json_value.h b/src/json_value.h
index 76b79f9..cdf797a 100644
--- a/src/json_value.h
+++ b/src/json_value.h
@@ -79,6 +79,18 @@ inline WeaselJsonCallbacks readValueCallbacks() {
       state->on_end_value();
     }
   };
+  result.on_key_data = +[](void *p, const char *buf, int len, int done) {
+    auto *state = (ReadValueState *)p;
+    if (!state->startedData) {
+      state->startedData = true;
+      state->valueStack.emplace_back(std::string());
+    }
+    std::get<std::string>(state->valueStack.back()).append(buf, len);
+    if (done) {
+      state->startedData = false;
+      state->on_end_value();
+    }
+  };
   result.on_begin_array = +[](void *p) {
     auto *state = (ReadValueState *)p;
     state->valueStack.emplace_back(std::make_unique<JsonArray>());
diff --git a/src/parser3.h b/src/parser3.h
index 4d4f10c..668f983 100644
--- a/src/parser3.h
+++ b/src/parser3.h
@@ -90,7 +90,11 @@ struct Parser3 {
     }
     assert(len >= 0);
     if (done || len > 0) {
-      callbacks->on_string_data(userdata, dataBegin, len, done);
+      if (inKey) {
+        callbacks->on_key_data(userdata, dataBegin, len, done);
+      } else {
+        callbacks->on_string_data(userdata, dataBegin, len, done);
+      }
     }
   }
 
@@ -141,6 +145,7 @@ struct Parser3 {
   uint32_t minCodepoint;
   NumDfa numDfa;
   Utf8Dfa strDfa;
+  bool inKey = false;
 };
 
 inline PRESERVE_NONE WeaselJsonStatus skipWhitespace(char *&buf, char *bufEnd) {
@@ -397,6 +402,8 @@ inline PRESERVE_NONE WeaselJsonStatus n_object2(Parser3 *self, char *buf,
     }
     MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
   case '"':
+    assert(!self->inKey);
+    self->inKey = true;
     ++buf;
     self->dataBegin = self->writeBuf = buf;
     self->pop();
@@ -432,6 +439,8 @@ inline PRESERVE_NONE WeaselJsonStatus n_object3(Parser3 *self, char *buf,
     MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
   case ',':
     ++buf;
+    assert(!self->inKey);
+    self->inKey = true;
     self->pop();
     if (auto s = self->push({N_STRING, T_COLON, N_VALUE, N_OBJECT3})) {
       return s;
@@ -726,7 +735,11 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex2(Parser3 *self, char *buf,
       w[0] = (0b00011111 & self->utf8Codepoint) | 0b11000000;
       w += 2;
       if (useTmp) [[unlikely]] {
-        self->callbacks->on_string_data(self->userdata, tmp, 2, false);
+        if (self->inKey) {
+          self->callbacks->on_key_data(self->userdata, tmp, 2, false);
+        } else {
+          self->callbacks->on_string_data(self->userdata, tmp, 2, false);
+        }
       }
     }
   } else {
@@ -760,7 +773,11 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex2(Parser3 *self, char *buf,
       w[0] = (0b00001111 & self->utf8Codepoint) | 0b11100000;
       w += 3;
       if (useTmp) [[unlikely]] {
-        self->callbacks->on_string_data(self->userdata, tmp, 3, false);
+        if (self->inKey) {
+          self->callbacks->on_key_data(self->userdata, tmp, 3, false);
+        } else {
+          self->callbacks->on_string_data(self->userdata, tmp, 3, false);
+        }
       }
     }
   }
@@ -818,7 +835,11 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex3(Parser3 *self, char *buf,
     w[0] = (0b00000111 & self->utf8Codepoint) | 0b11110000;
     w += 4;
     if (useTmp) [[unlikely]] {
-      self->callbacks->on_string_data(self->userdata, tmp, 4, false);
+      if (self->inKey) {
+        self->callbacks->on_key_data(self->userdata, tmp, 4, false);
+      } else {
+        self->callbacks->on_string_data(self->userdata, tmp, 4, false);
+      }
     }
   }
 
@@ -904,17 +925,12 @@ inline PRESERVE_NONE WeaselJsonStatus n_null(Parser3 *self, char *buf,
   }
 }
 
-template <char kChar, bool kSkipWhitespace = false>
+template <char kChar>
 inline PRESERVE_NONE WeaselJsonStatus singleChar(Parser3 *self, char *buf,
                                                  char *bufEnd) {
   if (buf == bufEnd) [[unlikely]] {
     return WeaselJson_REJECT;
   }
-  if constexpr (kSkipWhitespace) {
-    if (auto s = skipWhitespace(buf, bufEnd)) {
-      return s;
-    }
-  }
   if (*buf == kChar) {
     ++buf;
     self->pop();
@@ -927,6 +943,28 @@ inline PRESERVE_NONE WeaselJsonStatus singleChar(Parser3 *self, char *buf,
   }
 }
 
+inline PRESERVE_NONE WeaselJsonStatus t_colon(Parser3 *self, char *buf,
+                                              char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
+  if (auto s = skipWhitespace(buf, bufEnd)) {
+    return s;
+  }
+  if (*buf == ':') {
+    ++buf;
+    assert(self->inKey);
+    self->inKey = false;
+    self->pop();
+    if (buf == bufEnd) {
+      return WeaselJson_AGAIN;
+    }
+    MUSTTAIL return Parser3::keepGoing(self, buf, bufEnd);
+  } else [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
+}
+
 inline PRESERVE_NONE WeaselJsonStatus t_eof(Parser3 *, char *buf,
                                             char *bufEnd) {
   if (buf != bufEnd) [[unlikely]] {
@@ -963,7 +1001,7 @@ constexpr inline struct ContinuationTable {
     continuations[T_A] = singleChar<'a'>;
     continuations[T_L] = singleChar<'l'>;
     continuations[T_S] = singleChar<'s'>;
-    continuations[T_COLON] = singleChar<':', true>;
+    continuations[T_COLON] = t_colon;
     continuations[T_HEX] = t_hex;
     continuations[T_HEX2] = t_hex2;
     continuations[T_HEX3] = t_hex3;
diff --git a/src/test.cpp b/src/test.cpp
index eb70738..280d4f0 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -215,6 +215,10 @@ void doTestUnescapingUtf8(std::string const &escaped,
     auto &s = *(std::string *)p;
     s.append(buf, len);
   };
+  c.on_key_data = +[](void *p, const char *buf, int len, int /*done*/) {
+    auto &s = *(std::string *)p;
+    s.append(buf, len);
+  };
   auto *parser = WeaselJsonParser_create(1024, &c, &result, flags);
   auto copy = escaped;
   for (size_t i = 0; i < copy.size(); i += stride) {