diff --git a/scripts/autokey.py b/scripts/autokey.py
index 94000ea..95c8bb8 100644
--- a/scripts/autokey.py
+++ b/scripts/autokey.py
@@ -187,6 +187,19 @@ def line_starts_with(x: str) -> bool:
                     print(intf.version())
                     continue
 
+                elif line_equals(':humanizer'):
+                    # Print humanizer level
+                    print(intf.get_humanizer_level())
+                    continue
+
+                elif line_starts_with(':humanizer'):
+                    # Set humanizer level
+                    try:
+                        intf.set_humanizer_level(float(line[10:]))
+                    except ValueError:
+                        print('Invalid level?')
+                    continue
+
                 elif line_starts_with(':'):
                     # Unknown command?
                     print('Unknown command?')
diff --git a/scripts/superkey/interface.py b/scripts/superkey/interface.py
index 687c193..e59af4b 100644
--- a/scripts/superkey/interface.py
+++ b/scripts/superkey/interface.py
@@ -170,6 +170,13 @@ def get_buzzer_frequency(self) -> int:
         self.__send_packet(MessageID.REQUEST_GET_BUZZER_FREQUENCY)
         return self.__check_reply('<H')[0]
 
+    def get_humanizer_level(self) -> float:
+        """
+        Sends the `REQUEST_GET_HUMANIZER_LEVEL` command. Returns the current humanizer level as a fraction.
+        """
+        self.__send_packet(MessageID.REQUEST_GET_HUMANIZER_LEVEL)
+        return self.__check_reply('<f')[0]
+
     def get_invert_paddles(self) -> bool:
         """
         Sends the `REQUEST_GET_INVERT_PADDLES` command. Returns whether or not the paddles are inverted.
@@ -289,6 +296,13 @@ def set_buzzer_frequency(self, frequency: int):
         self.__send_packet(MessageID.REQUEST_SET_BUZZER_FREQUENCY, struct.pack('<H', frequency))
         self.__check_reply_empty()
 
+    def set_humanizer_level(self, level: float):
+        """
+        Sends the `REQUEST_SET_HUMANIZER_LEVEL` command. Sets the humanizer level as a fraction.
+        """
+        self.__send_packet(MessageID.REQUEST_SET_HUMANIZER_LEVEL, struct.pack('<f', level))
+        self.__check_reply_empty()
+
     def set_invert_paddles(self, inverted: bool):
         """
         Sends the `REQUEST_SET_INVERT_PADDLES` command. Sets whether the paddles are inverted.
diff --git a/scripts/superkey/types.py b/scripts/superkey/types.py
index 32ea143..090b5b7 100644
--- a/scripts/superkey/types.py
+++ b/scripts/superkey/types.py
@@ -109,6 +109,7 @@
         'REQUEST_AUTOKEY_QUICK_MSG',
         'REQUEST_GET_BUZZER_ENABLED',
         'REQUEST_GET_BUZZER_FREQUENCY',
+        'REQUEST_GET_HUMANIZER_LEVEL',
         'REQUEST_GET_INVERT_PADDLES',
         'REQUEST_GET_IO_POLARITY',
         'REQUEST_GET_IO_STATE',
@@ -126,6 +127,7 @@
         'REQUEST_RESTORE_DEFAULT_CONFIG',
         'REQUEST_SET_BUZZER_ENABLED',
         'REQUEST_SET_BUZZER_FREQUENCY',
+        'REQUEST_SET_HUMANIZER_LEVEL',
         'REQUEST_SET_INVERT_PADDLES',
         'REQUEST_SET_IO_POLARITY',
         'REQUEST_SET_IO_TYPE',
diff --git a/scripts/wordcopy.py b/scripts/wordcopy.py
index 010436a..fa7e2d3 100644
--- a/scripts/wordcopy.py
+++ b/scripts/wordcopy.py
@@ -22,6 +22,7 @@
 DEFAULT_WPM = 20.
 DEFAULT_MINLEN = 2
 DEFAULT_MAXLEN = 8
+DEFAULT_HUMANIZE = 0.
 
 # ----------------------------------------------------- PROCEDURES -----------------------------------------------------
 
@@ -38,6 +39,7 @@ def _parse_args():
     parser.add_argument('--wpm', type=float, default=DEFAULT_WPM, help='Words per minute.')
     parser.add_argument('--minlen', type=int, default=DEFAULT_MINLEN, help='Minimum word length.')
     parser.add_argument('--maxlen', type=int, default=DEFAULT_MAXLEN, help='Maximum word length.')
+    parser.add_argument('--humanizer', type=float, default=DEFAULT_HUMANIZE, help='Humanizer fraction.')
     return parser.parse_args()
 
 def _main(port: str,
@@ -47,7 +49,8 @@ def _main(port: str,
           delay: float,
           wpm: float,
           minlen: int,
-          maxlen: int):
+          maxlen: int,
+          humanizer: float):
     """
     Runs the trainer.
     """
@@ -62,10 +65,12 @@ def _main(port: str,
             # Get initial settings
             initial_wpm = intf.get_wpm()
             initial_trainer_mode = intf.get_trainer_mode()
+            initial_humanizer_level = intf.get_humanizer_level()
 
             # Override settings
             intf.set_wpm(wpm)
             intf.set_trainer_mode(True)
+            intf.set_humanizer_level(humanizer)
 
             # Run as many times as commanded
             for _ in range(count):
@@ -89,6 +94,7 @@ def _main(port: str,
             # Restore initial settings
             intf.set_wpm(initial_wpm)
             intf.set_trainer_mode(initial_trainer_mode)
+            intf.set_humanizer_level(initial_humanizer_level)
 
 
 # -------------------------------------------------- IMPORT PROCEDURE --------------------------------------------------
@@ -106,4 +112,5 @@ def _main(port: str,
           delay = args.delay,
           wpm = args.wpm,
           minlen = args.minlen,
-          maxlen = args.maxlen)
+          maxlen = args.maxlen,
+          humanizer = args.humanizer)
diff --git a/src/main/application/intf_port.c b/src/main/application/intf_port.c
index c5de6a5..d864994 100644
--- a/src/main/application/intf_port.c
+++ b/src/main/application/intf_port.c
@@ -140,6 +140,12 @@ static void process_message_request_get_buzzer_enabled( intf_header_t const * he
  */
 static void process_message_request_get_buzzer_frequency( intf_header_t const * header, void const * payload );
 
+/**
+ * @fn      process_message_request_get_humanizer_level( intf_header_t const *, void const * )
+ * @brief   Processes the specified interface message with the `INTF_MESSAGE_REQUEST_GET_HUMANIZER_LEVEL` message ID.
+ */
+static void process_message_request_get_humanizer_level( intf_header_t const * header, void const * payload );
+
 /**
  * @fn      process_message_request_get_invert_paddles( intf_header_t const *, void const * )
  * @brief   Processes the specified interface message with the `INTF_MESSAGE_REQUEST_GET_INVERT_PADDLES` message ID.
@@ -242,6 +248,12 @@ static void process_message_request_set_buzzer_enabled( intf_header_t const * he
  */
 static void process_message_request_set_buzzer_frequency( intf_header_t const * header, void const * payload );
 
+/**
+ * @fn      process_message_request_set_humanizer_level( intf_header_t const *, void const * )
+ * @brief   Processes the specified interface message with the `INTF_MESSAGE_REQUEST_SET_HUMANIZER_LEVEL` message ID.
+ */
+static void process_message_request_set_humanizer_level( intf_header_t const * header, void const * payload );
+
 /**
  * @fn      process_message_request_set_invert_paddles( intf_header_t const *, void const * )
  * @brief   Processes the specified interface message with the `INTF_MESSAGE_REQUEST_SET_INVERT_PADDLES` message ID.
@@ -443,6 +455,10 @@ static void process_message( intf_header_t const * header, void const * payload
         process_message_request_get_buzzer_frequency( header, payload );
         break;
 
+    case INTF_MESSAGE_REQUEST_GET_HUMANIZER_LEVEL:
+        process_message_request_get_humanizer_level( header, payload );
+        break;
+
     case INTF_MESSAGE_REQUEST_GET_INVERT_PADDLES:
         process_message_request_get_invert_paddles( header, payload );
         break;
@@ -511,6 +527,10 @@ static void process_message( intf_header_t const * header, void const * payload
         process_message_request_set_buzzer_frequency( header, payload );
         break;
 
+    case INTF_MESSAGE_REQUEST_SET_HUMANIZER_LEVEL:
+        process_message_request_set_humanizer_level( header, payload );
+        break;
+
     case INTF_MESSAGE_REQUEST_SET_INVERT_PADDLES:
         process_message_request_set_invert_paddles( header, payload );
         break;
@@ -658,6 +678,17 @@ static void process_message_request_get_buzzer_frequency( intf_header_t const *
 }   /* process_message_request_get_buzzer_frequency() */
 
 
+static void process_message_request_get_humanizer_level( intf_header_t const * header, void const * payload )
+{
+    ( void )payload;
+    VALIDATE_PAYLOAD_SIZE_OR_BAIL( 0 );
+
+    float level = keyer_get_humanizer_level();
+    send_packet( INTF_MESSAGE_REPLY_SUCCESS, & level, sizeof( level ) );
+
+}   /* process_message_request_get_humanizer_level() */
+
+
 static void process_message_request_get_invert_paddles( intf_header_t const * header, void const * payload )
 {
     ( void )payload;
@@ -875,6 +906,19 @@ static void process_message_request_set_buzzer_frequency( intf_header_t const *
 }   /* process_message_request_set_buzzer_frequency() */
 
 
+static void process_message_request_set_humanizer_level( intf_header_t const * header, void const * payload )
+{
+    VALIDATE_PAYLOAD_SIZE_OR_BAIL( sizeof( float ) );
+
+    float level = *( ( float const * )payload );
+    VALIDATE_RANGE_OR_BAIL( level, KEYER_HUMANIZER_LEVEL_MIN, KEYER_HUMANIZER_LEVEL_MAX );
+
+    keyer_set_humanizer_level( level );
+    send_empty_packet( INTF_MESSAGE_REPLY_SUCCESS );
+
+}   /* process_message_request_set_humanizer_level() */
+
+
 static void process_message_request_set_invert_paddles( intf_header_t const * header, void const * payload )
 {
     VALIDATE_PAYLOAD_SIZE_OR_BAIL( sizeof( bool ) );
diff --git a/src/main/application/intf_types.h b/src/main/application/intf_types.h
index c4a4573..71d5710 100644
--- a/src/main/application/intf_types.h
+++ b/src/main/application/intf_types.h
@@ -49,6 +49,7 @@ enum
     INTF_MESSAGE_REQUEST_AUTOKEY_QUICK_MSG, /**< Queues a quick message to be autokeyed.*/
     INTF_MESSAGE_REQUEST_GET_BUZZER_ENABLED,/**< Get buzzer enablement.                 */
     INTF_MESSAGE_REQUEST_GET_BUZZER_FREQUENCY,/**< Get buzzer frequency.                */
+    INTF_MESSAGE_REQUEST_GET_HUMANIZER_LEVEL,/**< Get humanizer level.                  */
     INTF_MESSAGE_REQUEST_GET_INVERT_PADDLES,/**< Gets paddle inversion setting.         */
     INTF_MESSAGE_REQUEST_GET_IO_POLARITY,   /**< Gets I/O pin polarity.                 */
     INTF_MESSAGE_REQUEST_GET_IO_STATE,      /**< Gets I/O pin state.                    */
@@ -66,6 +67,7 @@ enum
     INTF_MESSAGE_REQUEST_RESTORE_DEFAULT_CONFIG,/**< Restores default configuration.    */
     INTF_MESSAGE_REQUEST_SET_BUZZER_ENABLED,/**< Enable or disable buzzer.              */
     INTF_MESSAGE_REQUEST_SET_BUZZER_FREQUENCY,/**< Set buzzer frequency.                */
+    INTF_MESSAGE_REQUEST_SET_HUMANIZER_LEVEL,/**< Set humanizer level.                  */
     INTF_MESSAGE_REQUEST_SET_INVERT_PADDLES,/**< Sets paddle inversion setting.         */
     INTF_MESSAGE_REQUEST_SET_IO_POLARITY,   /**< Sets I/O pin polarity.                 */
     INTF_MESSAGE_REQUEST_SET_IO_TYPE,       /**< Sets I/O pin type.                     */
diff --git a/src/main/application/keyer.c b/src/main/application/keyer.c
index 905022c..5f53b1e 100644
--- a/src/main/application/keyer.c
+++ b/src/main/application/keyer.c
@@ -9,6 +9,7 @@
 
 /* ---------------------------------------------------- INCLUDES ---------------------------------------------------- */
 
+#include <math.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -66,6 +67,7 @@ enum
 static bool s_keyed = false;                /**< Is the keyer hardware currently keyed? */
 static bool s_panicked = false;             /**< Was the keyer panic activated?         */
 static bool s_trainer_mode = false;         /**< Is trainer mode on?                    */
+static float s_humanizer_level = KEYER_HUMANIZER_OFF;/**< Humanizer level.              */
 
 static state_t s_state = STATE_OFF;         /**< Currently active keyer state.          */
 
@@ -188,6 +190,12 @@ static bool get_keyed( void );
  */
 static state_t get_next_state( void );
 
+/**
+ * @fn      humanize_delay( tick_t )
+ * @brief   Applies a random variation to the specified delay.
+ */
+static tick_t humanize_delay( tick_t delay );
+
 /**
  * @fn      set_keyed( bool )
  * @brief   Sets whether the keyer hardware is keying or not.
@@ -253,6 +261,13 @@ size_t keyer_autokey_str_ex( char const * str, keyer_autokey_flag_field_t flags
 }   /* keyer_autokey_str() */
 
 
+float keyer_get_humanizer_level( void )
+{
+    return( s_humanizer_level );
+
+}   /* keyer_get_humanizer_level() */
+
+
 bool keyer_get_on( void )
 {
     return( get_keyed() );
@@ -287,6 +302,7 @@ void keyer_init( void )
     s_keyed = false;
     s_panicked = false;
     s_trainer_mode = false;
+    s_humanizer_level = KEYER_HUMANIZER_OFF;
     s_state = STATE_OFF;
     s_el = WPM_ELEMENT_NONE;
     s_lockout_el = WPM_ELEMENT_NONE;
@@ -316,6 +332,13 @@ void keyer_panic( void )
 }   /* keyer_panic() */
 
 
+void keyer_set_humanizer_level( float level )
+{
+    s_humanizer_level = clamp( level, KEYER_HUMANIZER_LEVEL_MIN, KEYER_HUMANIZER_LEVEL_MAX );
+
+}   /* keyer_set_humanizer_level() */
+
+
 void keyer_set_paddle_invert( bool invert )
 {
     config_t config;
@@ -877,9 +900,11 @@ static void do_state_autokey( tick_t tick, bool new_state )
         if( wpm_element_is_keyed( s_el ) )
         {
             s_lockout_el = s_el;
-            s_el_stop_tick = tick + s_ticks[ s_el ];
+            s_el_stop_tick = tick
+                + humanize_delay( s_ticks[ s_el ] );
             s_el_stop_tick_vld = true;
-            s_el_start_tick = tick + s_ticks[ s_el ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ];
+            s_el_start_tick = tick
+                + humanize_delay( s_ticks[ s_el ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] );
             s_el_start_tick_vld = true;
             set_keyed( true );
         }
@@ -887,11 +912,12 @@ static void do_state_autokey( tick_t tick, bool new_state )
         {
             s_el_stop_tick = 0;
             s_el_stop_tick_vld = false;
-            s_el_start_tick = tick + s_ticks[ s_el ]
-                            - ( prev_lockout_el_was_keyed ?
-                                s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] : 0 )
-                            - ( prev_el_was_letter_space ?
-                                ( s_ticks[ WPM_ELEMENT_LETTER_SPACE ] - s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] ) : 0 );
+            s_el_start_tick = tick
+                + humanize_delay( s_ticks[ s_el ]
+                                - ( prev_lockout_el_was_keyed ?
+                                    s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] : 0 )
+                                - ( prev_el_was_letter_space ?
+                                   ( s_ticks[ WPM_ELEMENT_LETTER_SPACE ] - s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] ) : 0 ) );
             s_el_start_tick_vld = true;
         }
     }
@@ -913,9 +939,11 @@ static void do_state_dashes( tick_t tick, bool new_state )
         // Activate keyer hardware
         s_el = WPM_ELEMENT_DASH;
         s_lockout_el = s_el;
-        s_el_stop_tick = tick + s_ticks[ WPM_ELEMENT_DASH ];
+        s_el_stop_tick = tick
+            + humanize_delay( s_ticks[ WPM_ELEMENT_DASH ] );
         s_el_stop_tick_vld = true;
-        s_el_start_tick = tick + s_ticks[ WPM_ELEMENT_DASH ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ];
+        s_el_start_tick = tick
+            + humanize_delay( s_ticks[ WPM_ELEMENT_DASH ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] );
         s_el_start_tick_vld = true;
         set_keyed( true );
     }
@@ -937,9 +965,11 @@ static void do_state_dots( tick_t tick, bool new_state )
         // Activate keyer hardware
         s_el = WPM_ELEMENT_DOT;
         s_lockout_el = s_el;
-        s_el_stop_tick = tick + s_ticks[ WPM_ELEMENT_DOT ];
+        s_el_stop_tick = tick
+            + humanize_delay( s_ticks[ WPM_ELEMENT_DOT ] );
         s_el_stop_tick_vld = true;
-        s_el_start_tick = tick + s_ticks[ WPM_ELEMENT_DOT ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ];
+        s_el_start_tick = tick
+            + humanize_delay( s_ticks[ WPM_ELEMENT_DOT ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] );
         s_el_start_tick_vld = true;
         set_keyed( true );
     }
@@ -961,9 +991,11 @@ static void do_state_interleaved( tick_t tick, bool new_state )
         // Activate keyer hardware
         s_el = ( s_lockout_el == WPM_ELEMENT_DOT ? WPM_ELEMENT_DASH : WPM_ELEMENT_DOT );
         s_lockout_el = s_el;
-        s_el_stop_tick = tick + s_ticks[ s_el ];
+        s_el_stop_tick = tick
+            + humanize_delay( s_ticks[ s_el ] );
         s_el_stop_tick_vld = true;
-        s_el_start_tick = tick + s_ticks[ s_el ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ];
+        s_el_start_tick = tick
+            + humanize_delay( s_ticks[ s_el ] + s_ticks[ WPM_ELEMENT_ELEMENT_SPACE ] );
         s_el_start_tick_vld = true;
         set_keyed( true );
     }
@@ -1113,6 +1145,20 @@ static state_t get_next_state( void )
 }   /* get_next_state() */
 
 
+static tick_t humanize_delay( tick_t delay )
+{
+    // Early check to avoid expensive floating point operations if not needed
+    if( s_humanizer_level == KEYER_HUMANIZER_OFF )
+        return( delay );
+
+    float rand = ( float )random() / ( float )RANDOM_MAX;
+    tick_t offset = ( tick_t )roundf( ( rand * s_humanizer_level )  * ( 0.5f * s_ticks[ WPM_ELEMENT_DOT ] ) );
+
+    return( delay + offset );
+
+}   /* humanize_delay() */
+
+
 static void set_keyed( bool keyed )
 {
     s_keyed = keyed;
diff --git a/src/main/application/keyer.h b/src/main/application/keyer.h
index ef19c2b..667e686 100644
--- a/src/main/application/keyer.h
+++ b/src/main/application/keyer.h
@@ -29,7 +29,25 @@
  * @def     KEYER_AUTOKEY_FLAG_NONE
  * @brief   Value for `keyer_autokey_flag_field_t` indicating that no flags are selected.
  */
-#define KEYER_AUTOKEY_FLAG_NONE ( 0 )
+#define KEYER_AUTOKEY_FLAG_NONE     0
+
+/**
+ * @def     KEYER_HUMANIZER_LEVEL_MIN
+ * @brief   Minimum humanizer level (unitless fraction).
+ */
+#define KEYER_HUMANIZER_LEVEL_MIN   0.0f
+
+/**
+ * @def     KEYER_HUMANIZER_LEVEL_MAX
+ * @brief   Maximum humanizer level (unitless fraction).
+ */
+#define KEYER_HUMANIZER_LEVEL_MAX   1.0f
+
+/**
+ * @def     KEYER_HUMANIZER_OFF
+ * @brief   Humanizer level value which disables the humanizer (unitless fraction).
+ */
+#define KEYER_HUMANIZER_OFF         KEYER_HUMANIZER_LEVEL_MIN
 
 /* ----------------------------------------------------- TYPES ------------------------------------------------------ */
 
@@ -123,6 +141,12 @@ size_t keyer_autokey_str( char const * str );
  */
 size_t keyer_autokey_str_ex( char const * str, keyer_autokey_flag_field_t flags );
 
+/**
+ * @fn      keyer_get_humanizer_level( void )
+ * @brief   Returns the current humanizer level.
+ */
+float keyer_get_humanizer_level( void );
+
 /**
  * @fn      keyer_get_on( void )
  * @brief   Returns `true` if the keyer is currently commanding the radio to transmit.
@@ -167,6 +191,13 @@ void keyer_init( void );
  */
 void keyer_panic( void );
 
+/**
+ * @fn      keyer_set_humanizer_level( float )
+ * @brief   Sets the current humanizer level.
+ * @note    The argument will be clamped to the range [`KEYER_HUMANIZER_MIN`, `KEYER_HUMANIZER_MAX`].
+ */
+void keyer_set_humanizer_level( float humanizer );
+
 /**
  * @fn      keyer_set_paddle_invert( bool )
  * @brief   Enables or disables the "invert paddles" setting. If set to `true`, the right paddle will emit dots and the