All of the pension files noted on these indexes can be scanned from the original documents at NARA DC with the exception of the Revolutionary War. Those files are on microfilm--originals cannot be scanned.
The items online at FamilySearch--which is what these links are for--are finding aids only, not the actual records.
WAR OF 1812 - The FGS volunteers are working to scan the 1812 pensions in color and they are being put on Fold3 (for free--through "D" as of this post) and are free without a subscription. https://www.familysearch.org/
"OLD WARS" (1815-1926):https://www.familysearch.org/
INDIAN WARS (1817 to 1898):https://www.familysearch.org/
CIVIL WAR - Besides the soldiers, this also includes Navy pension cards, which are difficult to read. The cards turned very dark when they were microfilmed, because the person doing the filming had the machine set to scan white cards that had the soldiers' pensions and did not adjust the machine for the blue sailors' pension cards:
SPANISH-AMERICAN WAR - The Civil War index (above) is for claims filed up to about 1930. It includes many Spanish-American War pension cards. The cards look the same as the Civil War, but any veterans of the SA War will have a tiny little letter handwritten "s" beside the word "invalid" next to where the application number is written.