Online Mapping Tools - Geographic Information Systems (GIS)

QGIS

QGIS
A free and open source geographic information system for creating, editing, visualizing, analyzing and publishing geospatial information on Windows, Mac, Linux, BSD and mobile devices.

Dropchop
Fully functional online GIS tool that easily lets users drop in existing data or draw right onto the map. This application is particularly useful in that it also allows common geoprocessing tasks to run right in the browser, with no need to install GIS software.

No sign-up is required.

ArcGIS Online
ArcGIS offers free online mapping services and allows users to share their maps with others. Save information as a CSV file and drag it right into the web application to visualize datasets. Visitors also can utilize a limited number of processing tools to evaluate mapped data.

New users must sign up for a free account in order to share or save maps.

Mapbox
Mapbox allows users to quickly build and share online web applications. Load CSV, KML or JSON files right into the browser and customize styles.

New users must create an account, and free accounts ("starter" accounts) are limited to 100MB of data storage and 50,000 map views a month. However, faculty and students can also request Mapbox Education accounts, which allow additional free storage capacity.

Map Stack
Create quick map snapshots of anywhere, with the ability to customize colors and which labels/lines to include.

Pyramid Shader
A specialized free application for visualizing terrain models and other digital raster data. Pyramid shader can create shaded relief, illuminated and shadowed contour lines, hypsometric colors, local hypsometric colors, exposition colors, bivariate colors, slope, aspect, and profile curvature. Pyramid Shader can generalize terrain by removing small high-frequency details and/or large landforms.

CartoDB
Like Mapbox, CartoDB is one of the more popular online mapping applications with a simple interface. Users can upload databases and map layers and visualize them right in the map. Like true GIS web applications, the maps are dynamic and change as the underlying datasets linked to them change.

New users must sign up for an account. Free accounts are limited to a maximum of 50MB of data, and the user cannot remove the CartoDB logo or keep data private once uploaded.