{"success":true,"version":"v1","request":{"tool":"list_calculators","category":"time"},"result":{"entity_type":"calculator_list","status":"completed","count":12,"calculators":[{"calculator_id":"time-zone-converter","entity_type":"calculator","name":"Time Zone Converter","category":"time","tool_name":"convert_time_zone","description":"Converts a wall-clock date and time from one IANA time zone to another using the tz database rules built into ICU, so the daylight-saving offsets in force on that date are applied automatically. Reports both UTC offsets, the UTC instant, the weekday and the day difference.","use_when":"You need to know what time an event scheduled in one city corresponds to in another city or in UTC on a specific date.","do_not_use_when":"You need the same instant in many zones at once (use world-clock), an epoch value (use unix-timestamp), or the elapsed time between two clock times (use time-duration).","required_inputs":["time","from_zone","to_zone"],"optional_inputs":["date"],"urls":{"html":"https://tttkmbb.com/time/time-zone-converter","markdown":"https://tttkmbb.com/time/time-zone-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/time-zone-converter","api":"https://tttkmbb.com/api/v1/calculate/time-zone-converter"}},{"calculator_id":"world-clock","entity_type":"calculator","name":"World Clock Calculator","category":"time","tool_name":"calculate_world_clock","description":"Takes a reference date and time in one IANA time zone and lists the corresponding local date, time, weekday and UTC offset in each zone of a list, using the tz database rules built into ICU (daylight saving included).","use_when":"You are scheduling across several cities and need the local time in each of them for one instant, or want to see the spread of UTC offsets.","do_not_use_when":"You only convert between two zones (use time-zone-converter) or need an epoch value (use unix-timestamp).","required_inputs":["zones"],"optional_inputs":["date","time","zone"],"urls":{"html":"https://tttkmbb.com/time/world-clock","markdown":"https://tttkmbb.com/time/world-clock.md","schema":"https://tttkmbb.com/api/v1/calculators/world-clock","api":"https://tttkmbb.com/api/v1/calculate/world-clock"}},{"calculator_id":"unix-timestamp","entity_type":"calculator","name":"Unix Timestamp Converter","category":"time","tool_name":"convert_unix_timestamp","description":"Converts a Unix timestamp (seconds or milliseconds since 1970-01-01T00:00:00Z, auto-detected) to a UTC and local date-time, or an ISO 8601 date-time (with optional time, offset or IANA zone) to epoch seconds and milliseconds, plus weekday, day of year and ISO week.","use_when":"You need to decode an epoch value from logs or an API, or produce the epoch seconds for a given calendar date and time.","do_not_use_when":"You need Julian Day numbers (use julian-date) or wall-clock conversion between two cities (use time-zone-converter).","required_inputs":[],"optional_inputs":["timestamp","datetime","time_zone"],"urls":{"html":"https://tttkmbb.com/time/unix-timestamp","markdown":"https://tttkmbb.com/time/unix-timestamp.md","schema":"https://tttkmbb.com/api/v1/calculators/unix-timestamp","api":"https://tttkmbb.com/api/v1/calculate/unix-timestamp"}},{"calculator_id":"haversine-distance","entity_type":"calculator","name":"Haversine Distance Calculator","category":"time","tool_name":"calculate_haversine_distance","description":"Computes the great-circle (as-the-crow-flies) distance between two points on a spherical Earth with the haversine formula, in kilometres, miles and nautical miles, together with the initial bearing, compass direction and the midpoint of the route.","use_when":"You need the straight-line distance between two GPS coordinates or cities, e.g. for flight distance, range checks or geofencing.","do_not_use_when":"You need road distance, or ellipsoidal accuracy better than about 0.5 % (use a geodesic method such as Vincenty or Karney on WGS-84); for bearings and compass points use compass-bearing.","required_inputs":["lat1","lon1","lat2","lon2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/time/haversine-distance","markdown":"https://tttkmbb.com/time/haversine-distance.md","schema":"https://tttkmbb.com/api/v1/calculators/haversine-distance","api":"https://tttkmbb.com/api/v1/calculate/haversine-distance"}},{"calculator_id":"compass-bearing","entity_type":"calculator","name":"Compass Bearing Calculator","category":"time","tool_name":"calculate_compass_bearing","description":"Computes the initial (forward) and final bearing of the great-circle route between two latitude/longitude points, the back bearing for the return trip, the matching 16-point compass directions and the distance.","use_when":"You need the heading from one coordinate to another for navigation, antenna or solar alignment, or want a bearing expressed as a compass point such as NNE.","do_not_use_when":"You only need the distance (use haversine-distance) or a bearing relative to magnetic north (apply the local magnetic declination separately).","required_inputs":["lat1","lon1","lat2","lon2"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/time/compass-bearing","markdown":"https://tttkmbb.com/time/compass-bearing.md","schema":"https://tttkmbb.com/api/v1/calculators/compass-bearing","api":"https://tttkmbb.com/api/v1/calculate/compass-bearing"}},{"calculator_id":"coordinate-converter","entity_type":"calculator","name":"Coordinate Converter","category":"time","tool_name":"convert_coordinates","description":"Parses a latitude and longitude given either as signed decimal degrees or as degrees-minutes-seconds text (with N/S/E/W letters, symbols, colons or spaces) and returns all three standard forms: decimal degrees, DMS and degrees with decimal minutes, with hemisphere letters.","use_when":"You have coordinates in one notation (e.g. 33°52′6″S from a map or a marine GPS in degrees-decimal-minutes) and need them as decimal degrees for an API, or the other way round.","do_not_use_when":"You need distances or bearings between points (use haversine-distance or compass-bearing) or conversions between datums or projected systems such as UTM.","required_inputs":["latitude","longitude"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/time/coordinate-converter","markdown":"https://tttkmbb.com/time/coordinate-converter.md","schema":"https://tttkmbb.com/api/v1/calculators/coordinate-converter","api":"https://tttkmbb.com/api/v1/calculate/coordinate-converter"}},{"calculator_id":"sunrise-sunset","entity_type":"calculator","name":"Sunrise and Sunset Calculator","category":"time","tool_name":"calculate_sunrise_sunset","description":"Computes sunrise, sunset, solar noon, day length and civil twilight for any date, latitude and longitude with the NOAA Solar Calculator algorithm (Meeus-based solar position, equation of time, zenith 90.833° for refraction and the solar disc), reported in an IANA time zone.","use_when":"You need sunrise/sunset or daylight hours for a place and date, e.g. for photography, outdoor planning, solar energy or prayer-time style scheduling.","do_not_use_when":"You need minute-exact times for legal purposes, times at elevations far above sea level or with obstructed horizons, or moonrise/moonset (not covered); use moon-phase for the lunar phase.","required_inputs":["latitude","longitude"],"optional_inputs":["date","time_zone"],"urls":{"html":"https://tttkmbb.com/time/sunrise-sunset","markdown":"https://tttkmbb.com/time/sunrise-sunset.md","schema":"https://tttkmbb.com/api/v1/calculators/sunrise-sunset","api":"https://tttkmbb.com/api/v1/calculate/sunrise-sunset"}},{"calculator_id":"moon-phase","entity_type":"calculator","name":"Moon Phase Calculator","category":"time","tool_name":"calculate_moon_phase","description":"Estimates the Moon's phase name, illuminated fraction and age (days since new moon) for a calendar date from the mean synodic month of 29.530588853 days counted from the new moon of 2000-01-06 18:14 UTC, plus the dates of the next new and full moons.","use_when":"You need the approximate lunar phase for a date, e.g. for night photography, fishing or tide context, gardening calendars or historical dates.","do_not_use_when":"You need phase times to the hour, eclipse predictions or moonrise/moonset (use an ephemeris such as USNO or JPL Horizons); for daylight times use sunrise-sunset.","required_inputs":[],"optional_inputs":["date"],"urls":{"html":"https://tttkmbb.com/time/moon-phase","markdown":"https://tttkmbb.com/time/moon-phase.md","schema":"https://tttkmbb.com/api/v1/calculators/moon-phase","api":"https://tttkmbb.com/api/v1/calculate/moon-phase"}},{"calculator_id":"easter-date","entity_type":"calculator","name":"Easter Date Calculator","category":"time","tool_name":"calculate_easter_date","description":"Computes the date of Western (Gregorian) Easter Sunday for any year with the Meeus/Jones/Butcher algorithm and derives Ash Wednesday, Palm Sunday, Good Friday, Ascension Day and Pentecost; also gives Orthodox Easter from the Julian computus converted to the Gregorian calendar.","use_when":"You need Easter or the movable feasts tied to it (Lent, Holy Week, Ascension, Pentecost) for a year, including the Orthodox date.","do_not_use_when":"You need fixed-date holidays or non-Christian movable holidays (Passover, Ramadan, Diwali), or dates before 1583 when the Gregorian calendar did not exist.","required_inputs":["year"],"optional_inputs":[],"urls":{"html":"https://tttkmbb.com/time/easter-date","markdown":"https://tttkmbb.com/time/easter-date.md","schema":"https://tttkmbb.com/api/v1/calculators/easter-date","api":"https://tttkmbb.com/api/v1/calculate/easter-date"}},{"calculator_id":"julian-date","entity_type":"calculator","name":"Julian Date Calculator","category":"time","tool_name":"convert_julian_date","description":"Converts a Gregorian calendar date and time (in UTC or an IANA zone) to the astronomical Julian Day Number, Julian Date (JD), Modified Julian Date (MJD), Truncated Julian Date, days since the J2000.0 epoch and Julian centuries, plus day of year and ISO week.","use_when":"You need JD/MJD values for astronomy, satellite or ephemeris work, or want to know the day count between dates via Julian Day Numbers.","do_not_use_when":"You mean the 'Julian date' used in food packaging or the military (a day-of-year number such as 2026-266; see day-of-week for day of year) or Unix epoch seconds (use unix-timestamp).","required_inputs":[],"optional_inputs":["date","time","time_zone"],"urls":{"html":"https://tttkmbb.com/time/julian-date","markdown":"https://tttkmbb.com/time/julian-date.md","schema":"https://tttkmbb.com/api/v1/calculators/julian-date","api":"https://tttkmbb.com/api/v1/calculate/julian-date"}},{"calculator_id":"retirement-countdown","entity_type":"calculator","name":"Retirement Countdown Calculator","category":"time","tool_name":"calculate_retirement_countdown","description":"Computes the date on which a person reaches a chosen retirement age from their date of birth and counts the days, weeks, calendar months and Monday–Friday working days remaining from a reference date.","use_when":"You want to know when someone reaches retirement age (default 67, the US full retirement age for people born in 1960 or later) and how long is left.","do_not_use_when":"You need the savings required to retire (use retirement-savings or fire-number) or a pension-rule specific eligibility date; national retirement ages vary and must be entered explicitly.","required_inputs":["birth_date"],"optional_inputs":["retirement_age","as_of_date"],"urls":{"html":"https://tttkmbb.com/time/retirement-countdown","markdown":"https://tttkmbb.com/time/retirement-countdown.md","schema":"https://tttkmbb.com/api/v1/calculators/retirement-countdown","api":"https://tttkmbb.com/api/v1/calculate/retirement-countdown"}},{"calculator_id":"anniversary","entity_type":"calculator","name":"Anniversary Calculator","category":"time","tool_name":"calculate_anniversary","description":"Counts completed years, months and days since a start date (wedding, job, founding), finds the next anniversary date and the days until it, and names the traditional anniversary gift material for that year.","use_when":"You want to know which anniversary is coming up, how many days remain until it, or the traditional gift for a given anniversary year.","do_not_use_when":"You need someone's age (use age) or a general date difference with business days (use date-difference).","required_inputs":["start_date"],"optional_inputs":["as_of_date"],"urls":{"html":"https://tttkmbb.com/time/anniversary","markdown":"https://tttkmbb.com/time/anniversary.md","schema":"https://tttkmbb.com/api/v1/calculators/anniversary","api":"https://tttkmbb.com/api/v1/calculate/anniversary"}}]},"timestamp":"2026-09-24T01:52:57Z","next_actions":[],"links":{"docs":"https://tttkmbb.com/calculators.md"}}