To get the latest release of SequenceServer, run the following from a command line.
gem install sequenceserver
If that doesn't work, try sudo gem instead of gem.
To configure and launch SequenceServer, run the following from a command line.
SequenceServer will automatically guide you through an interactive setup process to help locate or download BLAST+ binaries, ask for the location of FASTA files (or BLAST+ databases), and offer to create BLAST+ databases from FASTA files.
That's it! Open http://localhost:4567/ and start BLAST-ing!