Western House Cusps API

Western House Cusps

Returns the complete house cusp positions for a Western natal astrology chart in the tropical zodiac — the structural framework that divides the natal chart into twelve houses, each governing a specific domain of life. House cusps are among the most location- and time-sensitive elements of a natal chart, since they are calculated from the intersection of the ecliptic with the horizon and meridian at the exact moment and place of birth. The house system used is fully configurable, making this endpoint the definitive source for house framework data across all major Western house division methods.

What This API Does

This endpoint accepts an individual's birth details (date, time, and geographic coordinates) and computes the tropical zodiac degree of each of the twelve house cusps using the house system specified via the X-House-Type header. It calculates the Ascendant (1st house cusp), Midheaven (10th house cusp), and all intermediate house cusps according to the mathematical model of the selected house system, then returns the complete house framework alongside the four primary chart angles — Ascendant, Descendant, Midheaven, and Imum Coeli. The response also includes the zodiac sign on each house cusp and the identity of each house's ruling planet based on that sign, providing the interpretive layer needed to assess each house's themes and the planets responsible for governing each life domain.

Data Returned

The response provides the complete house cusp framework for the tropical natal chart:

• Twelve house cusp positions — the tropical zodiac sign, degree, and minute of arc for each of the twelve house cusps (1st through 12th), calculated according to the specified house system

• Ascendant — the precise tropical degree of the Ascendant (1st house cusp), the most personally significant angle in the Western natal chart, representing the individual's outward persona, physical appearance, and approach to life

• Midheaven (MC) — the precise tropical degree of the Midheaven (10th house cusp), representing career, public reputation, life direction, and the individual's highest aspirations

• Descendant — the tropical degree of the Descendant (7th house cusp), the axis of relationships, partnerships, and open enemies

• Imum Coeli (IC) — the tropical degree of the Imum Coeli (4th house cusp), representing home, family, roots, and the private self

• Sign on each house cusp — the zodiac sign occupying each house cusp, which determines the house's thematic coloring and the planet that rules that house in the natal chart

• House ruler identity — the ruling planet of each house based on the sign on its cusp, a key element of natal chart interpretation used to trace the themes of each house through the chart

• House system identification — confirmation of the house system used for the calculation, reflecting the X-House-Type header value

• Intercepted signs — where applicable (in house systems that produce unequal houses), identification of any zodiac signs that are fully contained within a house without appearing on a cusp, a significant interpretive factor in some Western astrological traditions

Main Use Cases

• Natal chart house framework generation — computing the complete house cusp structure as the spatial framework for a Western natal chart, establishing which zodiac signs and degrees govern each of the twelve life domains

• Multi-house-system support — leveraging the configurable X-House-Type header to generate house cusps under any of the major Western house systems (Placidus, Koch, Whole Sign, Equal House, Campanus, Regiomontanus, Porphyry, and others), enabling platforms to support user preference for different house division methods

• House ruler analysis — using the sign-on-cusp and house ruler data to trace the themes of each house through the natal chart, identifying which planets govern which life domains and where those rulers are placed

• Ascendant and angle analysis — accessing the precise degrees of all four chart angles (Ascendant, Descendant, Midheaven, IC) for natal interpretation, solar arc direction, and transit sensitivity analysis

• Intercepted sign identification — identifying intercepted signs in house systems that produce unequal houses, a factor that some Western practitioners consider significant in natal interpretation

• Chart rendering and visualization — providing the house cusp degree data needed to accurately render the twelve-house wheel structure in natal chart visualization features

• Comparative house system analysis — running the endpoint with different X-House-Type values for the same birth data to compare how house cusps shift across different house systems, supporting practitioners who work with or teach multiple house division methods

Key Functionality

• Supports a fully configurable house system via the X-House-Type header, enabling house cusp calculations under any of the major Western house division methods — including Placidus, Koch, Whole Sign, Equal House, Campanus, Regiomontanus, Porphyry, Alcabitius, Morinus, and others — making this endpoint the single source for house framework data regardless of the practitioner's or platform's preferred system

• Returns all four primary chart angles — Ascendant, Descendant, Midheaven, and Imum Coeli — prominently alongside the twelve house cusps, since these angles are the most interpretively significant points in the Western natal chart and are used extensively in transit, progression, and solar arc analysis

• Returns the sign on each house cusp and the house ruler identity for all twelve houses, providing the interpretive layer that connects the structural house framework to the planetary rulership system

• Identifies intercepted signs where the selected house system produces unequal houses large enough to contain a full zodiac sign without it appearing on a cusp — a feature relevant for Placidus, Koch, and other quadrant-based systems at higher latitudes

• Computes all positions in the tropical zodiac, consistent with the Western natal astrology framework

• Supports configurable lunar node type via the X-Node-Type header for consistency with other Western endpoints that include node positions

• Accepts only birth details (date, time, latitude, longitude, and timezone) with no current location required, since natal house cusps are based entirely on the birth chart

• Is highly latitude-sensitive — house cusp calculations, particularly in quadrant-based systems like Placidus and Koch, vary significantly with geographic latitude, and the endpoint correctly handles births at high latitudes where some house systems produce extreme or undefined results

• Designed for localization — the Accept-Language header controls the language of zodiac sign names, house names, planet names, and all descriptive content in the response

• Serves as the house framework endpoint — providing the structural data that underpins house-based natal interpretation, house ruler analysis, and chart visualization