Large-scale studies such as the Arabidopsis thaliana "1,001 Genomes" Project require routine genotyping of stocks to avoid sample contamination. To genotype samples efficiently and economically, sequencing must be inexpensive and data processing simple. Here we present SNPmatch, a tool that identifies strains (or inbred lines, or accessions) by matching them to a SNP database. We tested the tool by performing low-coverage resequencing of over 2,000 strains from our lab seed stock collection. SNPmatch correctly genotyped samples from 1-fold coverage sequencing data, and could also identify the parents of F1 or F2 individuals. SNPmatch can be run either on the command line or through AraGeno (https://arageno.gmi.oeaw.ac.at), a web interface that permits sample genotyping from a user-uploaded VCF or BED file.