SVG Transit Chart Generator

POST/api/v1/natal/chart/transits

Generate a bi-wheel transit chart showing current planetary positions overlaid on a natal chart. Natal planets appear in the outer ring (blue by default), transit planets in the inner ring (red by default). Full control over colors, aspect lines, and visual styling.

For unknown natal birth time, pass natal.time_known: false to omit houses and angles.

Full URL

https://api.freeastroapi.com/api/v1/natal/chart/transits

Natal Subject Parameters (nested inside `natal` object)

Birth chart details for the subject.

Parameter	Type	Required	Default	Description
name	string	Yes	-	Subject name
year	integer	Yes	-	Birth year
month	integer	Yes	-	Birth month (1-12)
day	integer	Yes	-	Birth day (1-31)
hour	integer	Yes	-	Birth hour (0-23)
minute	integer	Yes	-	Birth minute (0-59)
time_known	boolean	No	true	Set false when natal birth time is unknown. Houses and angles are omitted on the natal wheel.
city	string	No	-	Birth city. Optional when lat/lng are provided.
lat	float	No	auto	Birth latitude. Required with lng if city is omitted.
lng	float	No	auto	Birth longitude. Required with lat if city is omitted.
tz_str	string	No	AUTO	Timezone (e.g. 'Europe/London' or 'AUTO')
house_system	string	No	placidus	placidus, whole_sign, equal, koch, etc.
zodiac_type	string	No	tropical	tropical or sidereal
format	string	No	svg	Output format: 'svg' or 'png'
size	integer	No	700	Chart width/height in pixels
theme_type	string	No	light	Theme: 'light', 'dark', or 'mono'
png_quality_scale	float	No	2.0	PNG resolution multiplier (1.0-5.0)
show_metadata	boolean	No	true	Show metadata block in chart

Transit Parameters (top-level)

Where and when to calculate the transit sky.

Parameter	Type	Required	Default	Description
current_city	string	Yes	-	City for transit planet positions
current_lat	float	No	auto	Transit latitude (optional)
current_lng	float	No	auto	Transit longitude (optional)
transit_date	string	No	now	Transit datetime ISO format: YYYY-MM-DDTHH:MM (defaults to current moment)
tz_str	string	No	AUTO	Timezone for transit location

Aspect Line Visibility (top-level)

Control which sets of aspect lines are drawn.

Parameter	Type	Required	Default	Description
show_inter_aspects	boolean	No	true	Show transit→natal aspect lines (cross-aspects)
show_natal_aspects	boolean	No	false	Show natal→natal aspect lines
show_transit_aspects	boolean	No	false	Show transit→transit aspect lines

Planet Colors (top-level)

Override planet symbol and degree text colors per ring. Pass null to use each planet's elemental color.

Parameter	Type	Required	Default	Description
natal_planet_color	string	No	#1565C0	Color for natal planet symbols + degree text (hex). Null = elemental colors.
transit_planet_color	string	No	#C62828	Color for transit planet symbols + degree text (hex). Null = elemental colors.

Display Settings (inside `natal.display_settings`)

Control which bodies appear on the natal ring.

Parameter	Type	Required	Default	Description
sun	boolean	No	true	Show Sun
moon	boolean	No	true	Show Moon
mercury	boolean	No	true	Show Mercury
venus	boolean	No	true	Show Venus
mars	boolean	No	true	Show Mars
jupiter	boolean	No	true	Show Jupiter
saturn	boolean	No	true	Show Saturn
uranus	boolean	No	true	Show Uranus
neptune	boolean	No	true	Show Neptune
pluto	boolean	No	true	Show Pluto
north_node	boolean	No	true	Show North Node
chiron	boolean	No	true	Show Chiron
lilith	boolean	No	true	Show Mean Black Moon Lilith (legacy alias for mean_lilith)
mean_lilith	boolean	No	false	Show Mean Black Moon Lilith
true_lilith	boolean	No	false	Show True (oscillating) Black Moon Lilith
eris	boolean	No	false	Show Eris
eros	boolean	No	false	Show Eros
part_of_fortune	boolean	No	false	Show Part of Fortune

Chart Configuration (inside `natal.chart_config`)

Fine-tune the visual appearance of the chart. All parameters are optional and placed inside the natal.chart_config object.

Parameter	Type	Required	Default	Description
sign_ring_thickness_fraction	float	No	0.16	Sign ring thickness (0.0–1.0)
house_ring_thickness_fraction	float	No	0.05	House ring thickness (0.0–1.0)
center_disk_fraction	float	No	0.45	Center disk radius (0.0–1.0)
planet_symbol_scale	float	No	0.35	Planet symbol size multiplier
sign_symbol_scale	float	No	0.6	Sign symbol size multiplier
house_number_scale	float	No	0.35	House number size multiplier
chart_background	string	No	null	Background color override (hex)
custom_planet_color	string	No	null	Override all planet colors (hex). Null = elemental colors.
custom_sign_color	string	No	null	Override all sign symbol colors (hex)
custom_house_color	string	No	null	Override all house number colors (hex)
custom_sign_bg_color	string	No	null	Single hex color for all 12 sign ring backgrounds. When set, sign backgrounds are automatically enabled.
custom_house_bg_color	string	No	null	Single hex color for all 12 house ring backgrounds. When set, house backgrounds are automatically enabled.
sign_line_width	float	No	2.0	Sign separator line width
house_line_width	float	No	1.0	House separator line width
asc_line_width	float	No	-	ASC axis line width
mc_line_width	float	No	-	MC axis line width
aspect_conjunction_width	float	No	-	Conjunction aspect line width
aspect_trine_width	float	No	-	Trine aspect line width
aspect_opposition_width	float	No	-	Opposition aspect line width
aspect_square_width	float	No	-	Square aspect line width
aspect_sextile_width	float	No	-	Sextile aspect line width
show_retrograde_markers	boolean	No	false	Enable retrograde markers on planet degree labels.
retrograde_marker_style	string	No	R	Retrograde marker style when enabled: "R" or "rx" (℞).
houses_inside_planets	boolean	No	true	Place houses inside planet ring (recommended for transit bi-wheel)
french_style	boolean	No	false	French bi-wheel layout: aspect disk inside sign rim, natal houses outside signs, natal planets outside houses, and transit planets in an outer lane.
french_planet_radius_offset	float	No	0	French-mode natal planet lane offset. Moves natal planet glyphs radially without moving the house/sign rings.
french_transit_planet_radius_offset	float	No	24	Regular French transit-mode planet lane offset. Moves transit glyphs radially without moving natal rings.
french_transit_degree_label_offset	float	No	-28	French transit-mode degree label offset. Positive moves labels inward; negative moves them outward.
french_transit_natal_planets_inside	boolean	No	false	French transit-mode variant. Moves the house ring, house numbers, and aspect disk inside like the normal SVG chart, places user/natal planets inside the sign ring, and keeps current-sky/transit planets outside.
french_transit_natal_inner_radius_offset	float	No	0	French transit-mode inner-natal variant. Adjusts the inner user planet lane radius.
french_transit_inner_natal_house_gap	float	No	60	French transit-mode inner-natal variant. Gap from sign inner ring to house outer ring; larger values make the house ring and aspect disk smaller.
french_transit_inner_natal_planet_radius_offset	float \| null	No	null	French transit-mode inner-natal variant. Overrides the current-sky/transit planet lane offset; null uses the close default for this mode.

Sample Code

curl -X POST "https://api.freeastroapi.com/api/v1/natal/chart/transits" \
 -H "Content-Type: application/json" \
 -H "x-api-key: YOUR_API_KEY" \
 -d '{
    "natal": {
        "name": "John Doe",
        "year": 1990,
        "month": 5,
        "day": 15,
        "hour": 14,
        "minute": 30,
        "time_known": false,
        "city": "London",
        "tz_str": "AUTO",
        "size": 700,
        "theme_type": "light",
        "format": "svg",
        "chart_config": {
            "custom_sign_bg_color": "#e8e0f0",
            "custom_house_bg_color": "#e0f0f8",
            "show_retrograde_markers": true,
            "retrograde_marker_style": "R",
            "french_style": true,
            "french_planet_radius_offset": 0,
            "french_transit_planet_radius_offset": 24,
            "french_transit_degree_label_offset": -28,
            "french_transit_natal_planets_inside": false,
            "french_transit_natal_inner_radius_offset": 0,
            "french_transit_inner_natal_house_gap": 60,
            "french_transit_inner_natal_planet_radius_offset": null,
            "custom_planet_color": null
        }
    },
    "current_city": "New York",
    "transit_date": "2026-02-26T12:00",
    "show_inter_aspects": true,
    "show_natal_aspects": false,
    "show_transit_aspects": false,
    "natal_planet_color": "#1565C0",
    "transit_planet_color": "#C62828"
}' --output transit_chart.svg

Related Endpoints

SVG Chart (Natal)

Single natal chart in SVG/PNG

Transits (JSON)

Transit aspect data in JSON format