Alignment File Formats

Jalview understands a wide range of sequence alignment formats. In order to determine which format has been used for an alignment, jalview tries to detect some text or formatting unique to one of the formats:

Format Unique File Feature File Extension
FASTA >SequenceName
THISISASEQUENCE
.fa, .fasta
MSF !! AA_MULTIPLE_ALIGNMENT 1.0
..
//
.msf
CLUSTALW CLUSTAL .aln
PILEUP PileUp
PIR >P1; .pir
BLC >Seq1
>Seq2
.blc
PFAM SequenceName THISISASEQUENCE .pfam
Stockholm # STOCKHOLM VersionNumber
...
//
.stk, .sto
Phylip Line starts with two numbers separated by white space
...
//
.phy

The file extensions are used to associate jalview alignment icons with alignment files: