How do I open a .dna file without SnapGene?

Drop it on this page. The SnapGene format is a run of packets (sequence, features, primers, notes) that is publicly documented; this page reads it in the browser and shows the map, features and sequence, with nothing to install.

Can I convert a SnapGene file to GenBank?

Yes. Open it and press Save GenBank. Features keep their type, location, strand and qualifiers, and primers are written as primer_bind features, so the file opens in Benchling, ApE, Geneious, Biopython and other tools. Display settings that only SnapGene uses (such as enzyme sets and history) are not carried over.

Does this page edit or design sequences?

No. It is a viewer and converter: you can look at, search and save the sequence, but not change bases, add features or simulate cloning.

How large a sequence can it show?

Up to 10 million bases, such as a bacterial genome. The sequence is shown a page at a time, and the maps draw the 400 longest features, with every feature in the list.

Which motifs can I search for?

Any run of bases using the IUPAC codes: A, C, G, T or U and N, R, Y, S, W, K, M, B, D, H, V. Both strands are searched, matches that overlap are all found, and on a circular plasmid a match that runs across the origin counts too.

Are my sequences uploaded?

No. The file is read by this browser tab on your device and never sent anywhere, which matters for unpublished constructs.

Stays on your computer How this works

Free SnapGene viewer: open .dna, GenBank and FASTA files online

See a SnapGene .dna file, GenBank or FASTA sequence without installing anything: plasmid map, linear map, features and primers, the sequence with annotations, motif search and GC content, saved as GenBank, FASTA, SVG or PNG. The file is read in your browser and is not uploaded.

Drag & drop a .dna, .gb or .fasta file here, or browse

SnapGene .dna · GenBank .gb .gbk · FASTA · up to 10 million bases · nothing is uploaded

About the SnapGene viewer

SnapGene saves DNA sequences as .dna files: the bases, whether the molecule is circular, its annotated features with their colours, primers and notes. Without SnapGene (or its free Viewer, which needs an install) there is no easy way to look at one, and labs often swap them with people who do not have it.

This page reads .dna files itself, along with GenBank and FASTA files, and draws a plasmid map and a linear map, lists the features and primers, and shows the sequence with its annotations, a position ruler and the other strand. It can find a sequence or IUPAC motif on both strands, gives the base counts and GC content, and saves the sequence as GenBank or FASTA and the map as SVG or PNG. It is free to use, with no account and no upload limit, and it runs entirely in your browser: nothing is uploaded, and while the page stays open, a feature you have already used keeps working offline.

What you can do

Open SnapGene .dna files, GenBank (.gb, .gbk, .ape) and FASTA files, including files with several sequences
See a circular plasmid map or a linear map with feature arrows, names, colours and primers
List features with type, location, length and strand, and their notes and qualifiers
Read the sequence with a position ruler, the other strand and feature bars, page by page up to 10 million bases
Find a sequence or IUPAC motif (such as GAATTC or GGNCC) on both strands, across the origin of a plasmid
Base counts and GC content
Save as GenBank or FASTA, and the map as SVG or PNG

How to open a SnapGene file

Drop the .dna, .gb or .fasta file on the box above, or click the box and choose it.
The map, features and sequence appear. Click a feature to pick it out on the map and jump to it in the sequence.
Type a sequence under "Find a sequence" to mark every match.
Use Save GenBank or Save FASTA to convert the file, or save the map as a picture.

Questions

How do I open a .dna file without SnapGene?: Drop it on this page. The SnapGene format is a run of packets (sequence, features, primers, notes) that is publicly documented; this page reads it in the browser and shows the map, features and sequence, with nothing to install.
Can I convert a SnapGene file to GenBank?: Yes. Open it and press Save GenBank. Features keep their type, location, strand and qualifiers, and primers are written as primer_bind features, so the file opens in Benchling, ApE, Geneious, Biopython and other tools. Display settings that only SnapGene uses (such as enzyme sets and history) are not carried over.
Does this page edit or design sequences?: No. It is a viewer and converter: you can look at, search and save the sequence, but not change bases, add features or simulate cloning.
How large a sequence can it show?: Up to 10 million bases, such as a bacterial genome. The sequence is shown a page at a time, and the maps draw the 400 longest features, with every feature in the list.
Which motifs can I search for?: Any run of bases using the IUPAC codes: A, C, G, T or U and N, R, Y, S, W, K, M, B, D, H, V. Both strands are searched, matches that overlap are all found, and on a circular plasmid a match that runs across the origin counts too.
Are my sequences uploaded?: No. The file is read by this browser tab on your device and never sent anywhere, which matters for unpublished constructs.