The FDR calculator uses the Benjamini-Hochberg method to identify which values from your data remain significant at an FDR of your choosing, when adjusting for multiple testing. The source code is available for inspection.
False Discovery Rate Online Calculator

The Extreme P calculator can accept extremely large Z scores and T scores (degrees of freedom must also be specified if providing T scores). It will yield an accurate P value to arbitrary limits, instead of the common cutuff of 2.225074e-308.
Extreme P Value Calculator