diff --git a/lib/date.c b/lib/date.c
new file mode 100644
index 0000000..43b80a0
--- /dev/null
+++ b/lib/date.c
@@ -0,0 +1,287 @@
+#include "date.h"
+
+struct date *date_copy(struct date *date_to_copy) {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_copy)");
+    exit(EXIT_FAILURE);
+  }
+  date->year = date_to_copy->year;
+  date->month = date_to_copy->month;
+  date->day = date_to_copy->day;
+  date->hours = date_to_copy->hours;
+  date->minutes = date_to_copy->minutes;
+  date->seconds = date_to_copy->seconds;
+  date->milliseconds = date_to_copy->milliseconds;
+  date->timezone_utc_offset = date_to_copy->timezone_utc_offset;
+  return date;
+}
+
+bool date_get_is_valid_year(uint16_t year) {
+  return year <= 9999;
+}
+
+bool date_get_is_valid_month(uint8_t month) {
+  return month >= 1 && month <= 12;
+}
+
+bool date_get_is_valid_day(uint8_t day) {
+  return day >= 1 && day <= 31;
+}
+
+bool date_get_is_valid_hours(uint8_t hours) {
+  return hours <= 23;
+}
+
+bool date_get_is_valid_minutes(uint8_t minutes) {
+  return minutes <= 59;
+}
+
+bool date_get_is_valid_seconds(uint8_t seconds) {
+  return seconds <= 59;
+}
+
+bool date_get_is_valid_milliseconds(uint16_t milliseconds) {
+  return milliseconds <= 999;
+}
+
+bool date_get_is_valid_timezone_utc_offset(int8_t timezone_utc_offset) {
+  return timezone_utc_offset >= -12 && timezone_utc_offset <= 14;
+}
+
+bool date_get_is_valid(struct date *date) {
+  size_t date_days_of_month = date_get_days_of_month(date->month, date->year);
+  return (date_get_is_valid_month(date->month) &&
+          date_get_is_valid_day(date->day) &&
+          date->day <= date_days_of_month &&
+          date_get_is_valid_hours(date->hours) &&
+          date_get_is_valid_minutes(date->minutes) &&
+          date_get_is_valid_seconds(date->seconds) &&
+          date_get_is_valid_milliseconds(date->milliseconds) &&
+          date_get_is_valid_timezone_utc_offset(date->timezone_utc_offset));
+}
+
+string_t date_to_iso_string(struct date *date_original) {
+  struct date *date = date_copy(date_original);
+  date_to_utc(date);
+
+  size_t iso_string_length = 24;
+  string_t result = malloc(sizeof(char) * (iso_string_length + 1));
+
+  string_t year_string = string_zero_pad(date->year, 4);
+  string_t month_string = string_zero_pad(date->month, 2);
+  string_t day_string = string_zero_pad(date->day, 2);
+  string_t hours_string = string_zero_pad(date->hours, 2);
+  string_t minutes_string = string_zero_pad(date->minutes, 2);
+  string_t seconds_string = string_zero_pad(date->seconds, 2);
+  string_t milliseconds_string = string_zero_pad(date->milliseconds, 3);
+  sprintf(result, "%s-%s-%sT%s:%s:%s.%sZ", year_string, month_string, day_string, hours_string, minutes_string, seconds_string, milliseconds_string);
+  free(year_string);
+  free(month_string);
+  free(day_string);
+  free(hours_string);
+  free(minutes_string);
+  free(seconds_string);
+  free(milliseconds_string);
+
+  free(date);
+  return result;
+}
+
+string_t date_to_iso_string_without_time(struct date *date) {
+  size_t iso_string_length = 10;
+  string_t result = malloc(sizeof(char) * (iso_string_length + 1));
+  if (result == NULL) {
+    perror("Error (date_to_iso_string_without_time)");
+    exit(EXIT_FAILURE);
+  }
+
+  string_t year_string = string_zero_pad(date->year, 4);
+  string_t month_string = string_zero_pad(date->month, 2);
+  string_t day_string = string_zero_pad(date->day, 2);
+  sprintf(result, "%s-%s-%s", year_string, month_string, day_string);
+  free(year_string);
+  free(month_string);
+  free(day_string);
+
+  return result;
+}
+
+struct date *date_from_iso_string(string_t iso_string) {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_from_iso_string)");
+    exit(EXIT_FAILURE);
+  }
+
+  string_t year_string = string_substring(iso_string, 0, 3);
+  date->year = (uint16_t)convert_string_to_number(year_string);
+  free(year_string);
+
+  string_t month_string = string_substring(iso_string, 5, 6);
+  date->month = (uint8_t)convert_string_to_number(month_string);
+  free(month_string);
+
+  string_t day_string = string_substring(iso_string, 8, 9);
+  date->day = (uint8_t)convert_string_to_number(day_string);
+  free(day_string);
+
+  string_t hours_string = string_substring(iso_string, 11, 12);
+  date->hours = (uint8_t)convert_string_to_number(hours_string);
+  free(hours_string);
+
+  string_t minutes_string = string_substring(iso_string, 14, 15);
+  date->minutes = (uint8_t)convert_string_to_number(minutes_string);
+  free(minutes_string);
+
+  string_t seconds_string = string_substring(iso_string, 17, 18);
+  date->seconds = (uint8_t)convert_string_to_number(seconds_string);
+  free(seconds_string);
+
+  string_t milliseconds_string = string_substring(iso_string, 20, 22);
+  date->milliseconds = (uint16_t)convert_string_to_number(milliseconds_string);
+  free(milliseconds_string);
+
+  date->timezone_utc_offset = 0;
+
+  return date;
+}
+
+uint8_t date_get_days_of_month(uint8_t month, uint16_t year) {
+  switch (month) {
+    case 1:
+      return 31;
+    case 2:
+      return date_get_is_leap_year(year) ? 29 : 28;
+    case 3:
+      return 31;
+    case 4:
+      return 30;
+    case 5:
+      return 31;
+    case 6:
+      return 30;
+    case 7:
+      return 31;
+    case 8:
+      return 31;
+    case 9:
+      return 30;
+    case 10:
+      return 31;
+    case 11:
+      return 30;
+    case 12:
+      return 31;
+    default:
+      return 0;
+  }
+}
+
+bool date_get_is_leap_year(uint16_t year) {
+  return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
+}
+
+uint64_t date_convert_milliseconds_to_seconds(uint16_t milliseconds) {
+  return milliseconds / MILLISECONDS_PER_SECOND;
+}
+
+uint64_t date_convert_seconds_to_milliseconds(uint64_t seconds) {
+  return seconds * MILLISECONDS_PER_SECOND;
+}
+
+uint64_t date_convert_days_to_seconds(uint64_t days) {
+  return days * SECONDS_PER_DAY;
+}
+
+uint64_t date_convert_hms_to_seconds(uint8_t hours, uint8_t minutes, uint8_t seconds) {
+  return (hours * SECONDS_PER_HOUR) + (minutes * SECONDS_PER_MINUTE) + seconds;
+}
+
+uint64_t date_to_total_seconds(struct date *date) {
+  uint64_t total_seconds = 0;
+
+  for (uint16_t year = 0; year < date->year; year++) {
+    total_seconds += 365 * SECONDS_PER_DAY;
+    if (date_get_is_leap_year(year)) {
+      total_seconds += SECONDS_PER_DAY;
+    }
+  }
+
+  for (uint8_t month = 1; month < date->month; month++) {
+    total_seconds += date_convert_days_to_seconds(date_get_days_of_month(month, date->year));
+  }
+
+  total_seconds += date_convert_days_to_seconds(date->day - 1);
+  total_seconds += date_convert_hms_to_seconds(date->hours, date->minutes, date->seconds);
+
+  return total_seconds;
+}
+
+uint64_t date_duration_seconds_between_2_dates(struct date *date1, struct date *date2) {
+  struct date *utc_date1 = date_copy(date1);
+  struct date *utc_date2 = date_copy(date2);
+  date_to_utc(utc_date1);
+  date_to_utc(utc_date2);
+
+  uint64_t total_seconds_date1 = date_to_total_seconds(utc_date1);
+  uint64_t total_seconds_date2 = date_to_total_seconds(utc_date2);
+
+  free(utc_date1);
+  free(utc_date2);
+
+  return total_seconds_date1 > total_seconds_date2 ? total_seconds_date1 - total_seconds_date2 : total_seconds_date2 - total_seconds_date1;
+}
+
+void date_add_hours(struct date *date, int64_t hours) {
+  if (hours == 0) {
+    return;
+  }
+  int64_t total_hours = date->hours + hours;
+  int64_t additional_days = total_hours / 24;
+  int64_t new_hours = total_hours % 24;
+
+  if (new_hours < 0) {
+    new_hours += 24;
+    additional_days -= 1;
+  }
+
+  date->hours = (uint8_t)new_hours;
+
+  if (additional_days != 0) {
+    date->day += additional_days;
+
+    while (date->day > date_get_days_of_month(date->month, date->year)) {
+      date->day -= date_get_days_of_month(date->month, date->year);
+      date->month++;
+
+      if (date->month > 12) {
+        date->month = 1;
+        date->year++;
+      }
+    }
+
+    while (date->day < 1) {
+      date->month--;
+      if (date->month < 1) {
+        date->month = 12;
+        date->year--;
+      }
+
+      date->day += date_get_days_of_month(date->month, date->year);
+    }
+  }
+}
+
+void date_add_days(struct date *date, int64_t days) {
+  date_add_hours(date, days * 24);
+}
+
+void date_to_utc(struct date *date) {
+  if (date->timezone_utc_offset == 0) {
+    return;
+  }
+  int8_t timezone_utc_offset = date->timezone_utc_offset;
+  date->timezone_utc_offset = 0;
+  date_add_hours(date, mathematics_opposite(timezone_utc_offset));
+}
diff --git a/lib/date.h b/lib/date.h
new file mode 100644
index 0000000..5d9e67d
--- /dev/null
+++ b/lib/date.h
@@ -0,0 +1,324 @@
+#ifndef __LIBCPROJECT_DATE__
+#define __LIBCPROJECT_DATE__
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "convert.h"
+#include "mathematics.h"
+#include "string.h"
+#include "types.h"
+
+#define SECONDS_PER_MINUTE 60
+#define SECONDS_PER_HOUR (60 * SECONDS_PER_MINUTE)
+#define SECONDS_PER_DAY (24 * SECONDS_PER_HOUR)
+#define MILLISECONDS_PER_SECOND 1000
+
+/**
+ * @brief Date object representing a single moment in time.
+ * @since v4.3.0
+ */
+struct date {
+  /**
+   * Year.
+   * Between [0, 9999] (inclusive).
+   * As per ISO 8601, a four-digit year [YYYY] and represents years from 0000 to 9999, year 0000 being equal to 1 BC and all others AD.
+   */
+  uint16_t year;
+
+  /**
+   * Month.
+   * Between [1, 12] (inclusive).
+   */
+  uint8_t month;
+
+  /**
+   * Day.
+   * Between [1, 31] (inclusive).
+   */
+  uint8_t day;
+
+  /**
+   * Hours.
+   * Between [0, 23] (inclusive).
+   */
+  uint8_t hours;
+
+  /**
+   * Minutes.
+   * Between [0, 59] (inclusive).
+   */
+  uint8_t minutes;
+
+  /**
+   * Seconds.
+   * Between [0, 59] (inclusive).
+   */
+  uint8_t seconds;
+
+  /**
+   * Milliseconds.
+   * Between [0, 999] (inclusive).
+   */
+  uint16_t milliseconds;
+
+  /**
+   * Timezone UTC offset.
+   * Between [-12, 14]
+   */
+  int8_t timezone_utc_offset;
+};
+
+/**
+ * @brief Return the copy of a date.
+ *
+ * @param date
+ * @return struct date*
+ * @since v4.3.0
+ */
+struct date *date_copy(struct date *date_to_copy);
+
+/**
+ * @brief Check if a year is valid, between [0, 9999] (inclusive).
+ *
+ * @param year
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_year(uint16_t year);
+
+/**
+ * @brief Check if a month is valid, between [1, 12] (inclusive).
+ *
+ * @param month
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_month(uint8_t month);
+
+/**
+ * @brief Check if a day is valid, between [1, 31] (inclusive).
+ *
+ * @param day
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_day(uint8_t day);
+
+/**
+ * @brief Check if hours are valid, between [0, 23] (inclusive).
+ *
+ * @param hours
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_hours(uint8_t hours);
+
+/**
+ * @brief Check if minutes are valid, between [0, 59] (inclusive).
+ *
+ * @param minutes
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_minutes(uint8_t minutes);
+
+/**
+ * @brief Check if seconds are valid, between [0, 59] (inclusive).
+ *
+ * @param seconds
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_seconds(uint8_t seconds);
+
+/**
+ * @brief Check if milliseconds are valid, between [0, 999] (inclusive).
+ *
+ * @param milliseconds
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_milliseconds(uint16_t milliseconds);
+
+/**
+ * @brief Check if the timezone UTC offset is valid, between [-12, 14] (inclusive).
+ *
+ * @param timezone_utc_offset
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_timezone_utc_offset(int8_t timezone_utc_offset);
+
+/**
+ * @brief Check if the date is valid (all fields are possible).
+ *
+ * @param date
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid(struct date *date);
+
+/**
+ * @brief String representing the date in the date time string format, a simplified format based on ISO 8601, which is always 24 characters long (`YYYY-MM-DDTHH:mm:ss.sssZ`). The timezone is always UTC, as denoted by the suffix `Z`.
+ *
+ * @param date
+ * @return string_t
+ *
+ * @code
+ * date_to_iso_string() // "2024-09-11T09:39:18.203Z"
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+string_t date_to_iso_string(struct date *date);
+
+/**
+ * @brief String representing the date in the ISO 8601 format, without time information (`YYYY-MM-DD`).
+ *
+ * @param date
+ * @return string_t
+ *
+ * @code
+ * date_to_iso_string_without_time() // "2024-09-11"
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+string_t date_to_iso_string_without_time(struct date *date);
+
+/**
+ * @brief Create a date from an ISO 8601 string, with the format `YYYY-MM-DDTHH:mm:ss.sssZ`.
+ *
+ * The timezone is always UTC, as denoted by the suffix `Z`.
+ *
+ * @param iso_string
+ * @return struct date*
+ * @since v4.3.0
+ */
+struct date *date_from_iso_string(string_t iso_string);
+
+/**
+ * @brief Get number of days in one month [1, 12].
+ *
+ * @param month
+ * @return uint8_t
+ * @since v4.3.0
+ */
+uint8_t date_get_days_of_month(uint8_t month, uint16_t year);
+
+/**
+ * @brief Determine if a year is a leap year.
+ *
+ * @param year
+ * @return bool
+ *
+ * @code
+ * date_is_leap_year(2020) // true
+ *
+ * date_is_leap_year(2021) // false
+ *
+ * date_is_leap_year(2022) // false
+ *
+ * date_is_leap_year(2023) // false
+ *
+ * date_is_leap_year(2024) // true
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+bool date_get_is_leap_year(uint16_t year);
+
+/**
+ * @brief Convert milliseconds to seconds.
+ *
+ * @param milliseconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_milliseconds_to_seconds(uint16_t milliseconds);
+
+/**
+ * @brief Convert seconds to milliseconds.
+ *
+ * @param seconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_seconds_to_milliseconds(uint64_t seconds);
+
+/**
+ * @brief Convert days to seconds.
+ *
+ * @param days
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_days_to_seconds(uint64_t days);
+
+/**
+ * @brief Convert hours, minutes, and seconds to seconds.
+ *
+ * @param hours
+ * @param minutes
+ * @param seconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_hms_to_seconds(uint8_t hours, uint8_t minutes, uint8_t seconds);
+
+/**
+ * @brief Convert a date to total seconds.
+ *
+ * @param date
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_to_total_seconds(struct date *date);
+
+/**
+ * @brief Calculate the duration in seconds between 2 dates.
+ *
+ * @param date1
+ * @param date2
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_duration_seconds_between_2_dates(struct date *date1, struct date *date2);
+
+/**
+ * @brief Add hours to the date, managing the day, month, year changes if necessary.
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date
+ * @param hours
+ * @since v4.3.0
+ */
+void date_add_hours(struct date *date, int64_t hours);
+
+/**
+ * @brief Adds days to the date, managing month and year changes as needed.
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date The date to which days are being added.
+ * @param days The number of days to add.
+ * @since v4.3.0
+ */
+void date_add_days(struct date *date, int64_t days);
+
+/**
+ * @brief Transform the date with a Timezone UTC Offset to UTC (timezone_utc_offset = 0).
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date
+ * @since v4.3.0
+ */
+void date_to_utc(struct date *date);
+
+#endif
diff --git a/libcproject.h b/libcproject.h
index 212d2d3..844de1b 100644
--- a/libcproject.h
+++ b/libcproject.h
@@ -4,6 +4,7 @@
 #include "lib/array_list.h"
 #include "lib/character.h"
 #include "lib/convert.h"
+#include "lib/date.h"
 #include "lib/filesystem.h"
 #include "lib/hash_map.h"
 #include "lib/linked_list.h"
diff --git a/test/date_test.c b/test/date_test.c
new file mode 100644
index 0000000..ba03d8b
--- /dev/null
+++ b/test/date_test.c
@@ -0,0 +1,164 @@
+#include "date_test.h"
+
+void date_test() {
+  date_copy_test();
+  date_to_iso_string_test();
+  date_to_iso_string_without_time_test();
+  date_from_iso_string_test();
+  date_get_is_leap_year_test();
+  date_duration_seconds_between_2_dates_test();
+  date_to_utc_test();
+}
+
+void date_copy_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  struct date *date2 = date_copy(date);
+  assert(date != date2);
+  assert(date->year == date2->year);
+  assert(date->month == date2->month);
+  assert(date->day == date2->day);
+  assert(date->hours == date2->hours);
+  assert(date->minutes == date2->minutes);
+  assert(date->seconds == date2->seconds);
+  assert(date->milliseconds == date2->milliseconds);
+  assert(date->timezone_utc_offset == date2->timezone_utc_offset);
+
+  date->year = 2025;
+  assert(date->year == 2025);
+  assert(date2->year == 2024);
+
+  free(date);
+  free(date2);
+}
+
+void date_to_iso_string_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  string_t iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T20:34:25.076Z"));
+  free(iso_string);
+
+  free(date);
+}
+
+void date_to_iso_string_without_time_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  string_t iso_string = date_to_iso_string_without_time(date);
+  assert(assert_string_equal(iso_string, "2024-09-10"));
+  free(iso_string);
+
+  free(date);
+}
+
+void date_from_iso_string_test() {
+  string_t iso_string = "2024-09-10T20:34:25.076Z";
+  struct date *date = date_from_iso_string(iso_string);
+  assert(date->year == 2024);
+  assert(date->month == 9);
+  assert(date->day == 10);
+  assert(date->hours == 20);
+  assert(date->minutes == 34);
+  assert(date->seconds == 25);
+  assert(date->milliseconds == 76);
+  assert(date->timezone_utc_offset == 0);
+
+  free(date);
+}
+
+void date_get_is_leap_year_test() {
+  assert(date_get_is_leap_year(2020));
+  assert(!date_get_is_leap_year(2021));
+  assert(!date_get_is_leap_year(2022));
+  assert(!date_get_is_leap_year(2023));
+  assert(date_get_is_leap_year(2024));
+}
+
+void date_duration_seconds_between_2_dates_test() {
+  struct date *date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  struct date *date2 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 0);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T23:34:26.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 10801);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T20:48:25.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 840);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T20:34:38.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 13);
+  free(date1);
+  free(date2);
+}
+
+void date_to_utc_test() {
+  struct date *date = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date->timezone_utc_offset = 3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  string_t iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T17:34:25.076Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date->timezone_utc_offset = -3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T23:34:25.076Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2024-01-01T00:00:00.000Z");
+  date->timezone_utc_offset = 3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2023-12-31T21:00:00.000Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2023-12-31T21:00:00.000Z");
+  date->timezone_utc_offset = -4;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-01-01T01:00:00.000Z"));
+  free(iso_string);
+  free(date);
+}
diff --git a/test/date_test.h b/test/date_test.h
new file mode 100644
index 0000000..3d9ddaf
--- /dev/null
+++ b/test/date_test.h
@@ -0,0 +1,25 @@
+#ifndef __DATE_TEST__
+#define __DATE_TEST__
+
+#include <assert.h>
+
+#include "libcproject.h"
+#include "test.h"
+
+void date_test();
+
+void date_copy_test();
+
+void date_to_iso_string_test();
+
+void date_to_iso_string_without_time_test();
+
+void date_from_iso_string_test();
+
+void date_get_is_leap_year_test();
+
+void date_duration_seconds_between_2_dates_test();
+
+void date_to_utc_test();
+
+#endif
diff --git a/test/main.c b/test/main.c
index 638a224..f488c73 100644
--- a/test/main.c
+++ b/test/main.c
@@ -4,6 +4,7 @@
 #include "array_list_test.h"
 #include "character_test.h"
 #include "convert_test.h"
+#include "date_test.h"
 #include "hash_map_test.h"
 #include "linked_list_test.h"
 #include "mathematics_test.h"
@@ -15,6 +16,7 @@ int main() {
   array_list_test();
   character_test();
   convert_test();
+  date_test();
   hash_map_test();
   linked_list_test();
   mathematics_test();