The libraries listed below are all open source. Note that some are hosted on GitHub, so simply checking out all the code under the "Source" tab above does not get you every library listed here. Instead, click the link next to the library you are interested in.

Day Night Overlay

Day Night Overlay provides a custom overlay which shows an approximation of where the day/night line runs at any given date.

Browse the github repository or see the live samples.

GeoJSON to Google Maps

The GeoJSON to Google Maps API library lets you easily convert GeoJSON to Overlays, along with default styling rules.

Browse the github repository for code and examples.

InfoBox

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This class behaves like google.maps.InfoWindow, but it supports several additional properties for advanced styling. An InfoBox can also be used as a map label.

Browse Released Versions or Development Versions.

Marker Clusterer

The library creates and manages per-zoom-level clusters for large amounts of markers. This is a V3 implementation of the V2 MarkerClusterer.

Browse Released Versions or Development Versions.

Marker Clusterer Plus

This is an enhanced version of the MarkerClusterer library for managing large amounts of markers. It adds support for several new properties as well as support for four more events. It also allows greater control over the styling of the text that appears on the cluster marker. The documentation has been significantly improved and the overall code has been simplified and polished. Very large numbers of markers can now be managed without causing Javascript timeout errors on Internet Explorer. It is backward compatible with MarkerClusterer.

Browse Released Versions or Development Versions.

Marker With Label

This class behaves like google.maps.Marker, but it supports the association of a label with the marker. If the marker is draggable, so too will be the label. In addition, a marker with a label responds to all mouse events in the same manner as a regular marker. It also fires mouse events and "property changed" events just as a regular marker would.

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Styled Marker

This class is a Marker that can be styled by changing its color, changing its shape, or adding text labels. Makes use of MVCObject to make changing styles for multiple markers easy.

Browse Development Versions.

Geolocation Marker

Adds a marker and accuracy circle to the map based on the user's location. Updates automatically as their location changes.

Browse Development Versions

Google Earth API

This library integrates the Google Earth API, and will render most map overlays appropriately in the 3D plugin.

Browse Development Versions.

Route Boxer

This class creates a set of LatLngBounds that are guaranteed to enclose every point within a given distance of a Polyline. It is intended to support adding Search along a route to an application backed by a spatial database that supports bounds queries (such as the Google Maps Data API).

Browse Released Versions or Development Versions.

ExtDraggableObject

This class sets up a DOM object to be draggable around the screen, similar to the V2 GDraggableObject. Has several extensions, such as the ability to restrict the object to vertical or horizontal only movement, move the object by a certain increment, or return the object to its original position before dragging started.

Browse Released Versions or Development Versions.

KeyDragZoom

This class allows a user to zoom in to an area on the map by holding down a hot key (e.g. Shift) while dragging a box around the area. Version 2.0 adds an optional visual control for turning zoom mode on and off.

Browse Released Versions or Development Versions.

RichMarker

A RichMarker that allows any HTML/DOM to be added to a map and be draggable.

Browse Development Versions.

InfoBubble

A InfoBubble is a customizable css3 infowindow.

Browse Development Versions.