Open FASTA files in your browser
The plainest file of DNA, RNA and protein sequences, from a single gene to a whole genome. Open a FASTA right here as a row for each sequence. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your sequences open as a row for each one, the first rows on show while the rest are read.
- A row for each sequence • ID, description, length and GC
- Sort and filter • Counts for every column
- Show details • Total length, N50 and GC content
- Export • Save as CSV, Excel, JSON or Parquet
About FASTA
FASTA files take their name from the FASTA search tool David Lipman and William Pearson wrote in 1985, and every sequencing and biology tool reads them now: NCBI, Ensembl and UniProt hand out genomes, genes and proteins as FASTA, and assemblers, aligners and BLAST take them in.
Each sequence starts with a line beginning with >, its ID and a description, followed by its letters on as many lines as it needs: A, C, G and T for DNA, U for RNA, or the amino acids' letters for a protein. A genome's FASTA, often named .fa or .fna, can hold chromosomes of hundreds of millions of letters, and a protein's is often .faa.
Filepeek reads the file in pieces in your browser and shows each sequence as a row with its ID, description, length and, for DNA, its GC content, with the start of its letters beside them, to sort, search and filter like any table. Show details sums up the file, its count, total length, N50 and GC, and Export saves the rows as CSV, Excel, JSON or Parquet.
FASTA sequence file
.fasta • .fa • .fna • .faa
Format
- MIME type
- text/x-fasta
- Made by
- David Lipman and William Pearson, for their FASTA software
- Released
- 1985
Inside the file
- Each sequence
- A > line, then its letters
- DNA and RNA
- A, C, G, T or U, and N for unknown
- Proteins
- The amino acids' letters
- Markup
- Plain text
Opens in every browser
Filepeek opens FASTA files of any size in Chrome, Edge, Firefox and Safari, read in pieces so the first sequences show at once. On their own, browsers download them or show them as text.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open FASTA
- WindowsNotepad shows its text • UGENE and SnapGene Viewer read it
- MacTextEdit shows its text • UGENE and SnapGene Viewer read it
- iPhone and iPadNo app opens it
- AndroidNo app opens it
Questions
How do I open the FASTA of a whole genome?
Drop it here. Filepeek reads it in pieces, so a genome of several GB opens as a row for each chromosome or contig with its length and GC, without being read into memory whole.
What's N50?
Take the longest sequences until they hold half of all the letters: the shortest of them is the N50. Assemblers use it to say how whole an assembly is, the higher the better. Show details gives it with the total length and GC content.
What do .fa, .fna and .faa mean?
They're all FASTA. NCBI names nucleotide files .fna and protein files .faa, and .fa is short for .fasta. Filepeek tells DNA from protein by the letters, whatever the name.
Why does my FASTA open as text?
A FASTA opens as a table when its first line starts with > and the lines after it read as sequence letters. A file with notes or a header before its first > opens as text.
Can I save the sequences as a spreadsheet?
Yes. Choose Export, then Save as CSV or Excel, with a row for each sequence and its ID, description, length and GC content.