With this service you can check compatibility of adapters, i.e. find out whether there are pairs among entered adapters, whose indices differ by less than 3 bases (this is the check mode). In the addition mode you can find out what adapters are compatible with those you entered. In the input form adapters from Truseq v1/v2/LT and single-index NEB are to be written as ADnumber, Truseq HT as Dnumber, Truseq Small RNA as RPInumber, Nextera as Nnumber or Snumber, dual-index NEB as inumber. The list with all adapters which the service knows can be found here Alternatively, you can write not an adapter name, but an index sequence itself. Just keep in mind that the length of an index sequence you enter sould be the same as the length that you have selected above the entry field. An example of the entry: BC7 BC2 GGATAT AD1 D703 ATACGA D711 D704 AD22 The check mode can also be used for dual-index runs. You can write either an adapter name or the index sequence itself. In the check mode for dual-index runs, the service will consider two index pairs compatible if there are at least 3 differences between them, overall. Adapter names or index sequences should be separated by hyphens or tabs. An example of the entry for dual-index runs: i701-i504 i701-i502 i709-i502 AD12-TruUni_Hi4_Nex AD15-TruUni_Hi4_Nex ATGGATCT-TruUni_Hi4_Nex N703-S502 AGCATTTT-S504 N707-GGGTCGCC ATCGGTTT-GAAAGTCA For error reports and suggestions please write to shelkmike@gmail.com . The logo was made with the help of one of Duran pictures (vk.com/by_duran). The Russian version of ЧЕК can be found here.