Free DNA file checker
Check your raw DNA file
Drop a 23andMe, AncestryDNA, MyHeritage, FamilyTreeDNA, Living DNA, WeGene or whole-genome VCF file below. In a few seconds you see what it is (company, chip, genome build, how many markers it holds and how many failed to read) and, if a DNA tool rejected it, the reason and the fix.
The check runs entirely in your browser. Your file is never uploaded, there is no account, and it is free. We count that a check ran and its outcome, such as “VCF, GRCh38, works”, and never the file, its name or any genotype.
Choose or drop your raw DNA file
.txt · .csv · .zip · .vcf · .vcf.gz
Read your DNA, free
Traits, medication genes, ancestry, your closest ancient peoples and your Neanderthal count. No account, and the report is read in your browser.
More free tools that read your file in the browser: Haplogroup finder (Y-DNA and mtDNA) · VCF to 23andMe format converter
Questions people ask
Why was my DNA file rejected?
Almost always for one of eight reasons. It is the PDF or web report, not the raw data. It is still zipped and the tool wants the .txt inside. The download stopped early. It is a .vcf.gz packed in BGZF blocks, which a tool using the browser’s built-in gzip reader can stop reading after the first 64 KB. It is a VCF with no rsIDs, which tools that match variants by name cannot use. Its coordinates are on GRCh38 and the tool expects GRCh37. It was opened and re-saved in a spreadsheet, which changes the separators. Or it is only part of an export. The checker above says which one applies to your file.
How do I check my raw DNA file?
Drop it on this page: it is read on your device and nothing is uploaded. To look by hand, open it in a text editor, not Excel. An array export starts with a few lines beginning with #, then one marker per line: an rsID such as rs4988235, a chromosome, a position and a two-letter genotype such as AG. A full array export has hundreds of thousands of these lines. A VCF starts with lines beginning with ## and a #CHROM header, and a whole genome lists 3 to 5 million variants.
Is my 23andMe file valid?
A valid 23andMe raw data download is a .zip with one .txt inside. The text starts with comment lines, the first reading “# This data file generated by 23andMe”, and then four tab-separated columns: rsid, chromosome, position and genotype. Recent v5 kits list roughly 630,000 markers on genome build 37. Lines that start with i instead of rs are 23andMe’s internal names and are normal. A genotype of -- is a no-call, a position the chip did not read; a small share is normal, usually well under 5%.
Is my file uploaded when I check it?
No. The file is opened and read by your browser, on your device, and never sent anywhere. The only thing the page downloads is our own public list of Neanderthal-matching sites, so it can tell you whether that count will run. We record that a check happened and its outcome, such as the file type and build, never the file, its name or any genotype.
What do GRCh37 and GRCh38 mean?
They are two editions of the human reference genome, and each gives the same variant a different address. Consumer chips still report on GRCh37 (also called build 37 or hg19). Many sequencing providers now deliver GRCh38. A tool that matches variants by position has to know which one your file uses, or it reads the wrong variants and gives confident, wrong answers. A file that names variants with rsIDs works on either.
My file works here, but another tool still rejects it. Why?
Each tool accepts different things. Some take only array exports and refuse any VCF, some cap the upload size, some want the file unzipped, and some accept only certain companies. The notes in your result, such as “zipped”, “BGZF” or “no rsIDs”, are the usual reasons, and each comes with the fix another tool is most likely to need.