Helioviewer.org
is an open-source project for the visualization of solar and heliospheric data. The project is funded by ESA and NASA.
For more information, please visit their Wiki.
Helioviewer's API for free access.
Helioviewer.org (Front-end interactive web-app)
isd.dmlab.cs.gsu.edu
is an open-source (in progress) project, a product of DMLab research group, that aims to integrate several different solar data repositories.
For more information, please visit the API.
ISD : isd.dmlab.cs.gsu.edu (Front-end interactive web-app)
ISD's API: http://api.isd.dmlab.cs.gsu.edu/
HEK (isolsearch)
The Heliophysics Events Knowledgebase (HEK) system is being developed to help solar and heliospheric researchers locate features and events of interest to their science topics.
isolsearch (Front-end interactive web-app)