View AB1 files in your browser
The file a sequencing service sends back for every Sanger read. Open one right here as its trace, with no FinchTV or SnapGene. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your read opens as its four curves, with the bases called and a quality bar for each.
- A, C, G and T in their colors • Calls and quality bars
- Zoom along the read • Taller or lower peaks
- Find bases on either strand • The reverse complement a click away
- Export • Save the read as FASTA or FASTQ
About AB1
Applied Biosystems' capillary sequencers, from the 3730 and 3500 to the SeqStudio, write every Sanger read as an .ab1, and sequencing services email them back by the dozen. Its format is ABIF, Applied Biosystems' own, which keeps the instrument's signal along with what it called.
Inside are tagged entries: the four dyes' curves, one each for A, C, G and T, the bases the basecaller read with where each peak sits, a quality for each base on Phred's scale, and the run's details, its sample, well, instrument and dates.
Filepeek reads it in your browser and draws the curves in the usual colors, A green, C blue, G black and T red, with the calls, their numbers and a quality bar for each. Zoom stretches the read or the peaks, a click on a base gives its place and quality, Find looks for bases on either strand, and Reverse complement turns the whole read around. Export saves it as FASTA, or as FASTQ with its qualities.
ABI sequencing trace
.ab1 • .abi
Format
- MIME type
- application/x-abi
- Made by
- Applied Biosystems, now part of Thermo Fisher Scientific
Inside the file
- Curves
- Four dyes, for A, C, G and T
- Calls
- Each base and where its peak is
- Quality
- Phred's, a value for each base
- Written as
- ABIF's tagged entries
Opens in every browser
Filepeek opens AB1 files in Chrome, Edge, Firefox and Safari, on any device. On their own, browsers only download them.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open AB1
- WindowsSnapGene Viewer, free • FinchTV and Chromas
- MacSnapGene Viewer, free • 4Peaks
- iPhone and iPadNo app opens it
- AndroidNo app opens it
Questions
How do I open an AB1 file without FinchTV?
Drop it on this page or choose Peek an AB1. The trace opens in your browser with its calls and qualities, on a phone too.
What does the bar under each base mean?
It's the quality the basecaller gave the base on Phred's scale: 20 means a 1 in 100 chance the call is wrong and 30 a 1 in 1,000. Bars under 20 are red, and the line over the trace counts the bases at 20 or better.
Why does the start of my read look messy?
The first 20 to 40 bases of a Sanger read are usually poor, as the shortest pieces run through the capillary unevenly, and the end fades as the signal does. The middle is where the calls are best.
Can I get the sequence out of an AB1?
Yes. Choose Export, then Save as FASTA, or Save as FASTQ to keep each base's quality. Choose Reverse complement first to save the other strand.