NRPSpredictor2 service had a minor issue the last days, which is now fixed (06/10/2015).
The current standalone version of NRPSpredictor2 can be found here
When using the NRPSpredictor in your work please cite:
Röttig et al. Nucleic Acids Research 39 (suppl 2): W362-W367 (2011) link
Rausch et al. Nucleic Acids Research 33(18): 5799-5808 (2005) link
The previous version can be found here link
A mirror site can be found here (please accept my self-signed certificate in your browser first).