fasta
What is a .fasta file?
text/x-fasta
FASTA is the plain-text format for biological sequences. Each record begins with a `>` header line carrying an identifier and free-form description, followed by the sequence itself wrapped over as many lines as needed using IUPAC single-letter codes for nucleotides or amino acids. It records no quality or alignment information, which is what keeps it universal.
How to use a .fasta file
Use an example .fasta file to test sequence parsers and pipeline entry points, checking multi-record splitting, tolerance of varying line widths and blank lines, correct handling of ambiguity codes, and that description text after the first whitespace is kept separate from the identifier.
Download example .fasta files
- FASTA Contigs — Wrapped at 60 Columns (.fasta)Four 600-base synthetic contigs wrapped at the conventional 60 columns, with the length and an invented organism name in each header. The sequences come from a fixed seed, so they are reproducible and belong to nothing that exists.
- FASTA Contigs — One Line Per Record (.fasta)The same four contigs written one sequence per line rather than wrapped, which is how many pipelines emit FASTA and how many line-oriented parsers assume it always looks. Comparing against the wrapped twin proves a parser joins continuation lines instead of taking the first one.
- Protein FASTA — Ambiguity Codes X, B and Z (.fasta)Three synthetic protein sequences that begin with methionine and include the X, B and Z ambiguity codes, which are legal IUPAC residues rather than errors. A validator restricted to the twenty standard amino acids rejects all three files.