barcodesDB • K-mer Lookup

K-mer Existence

Paste k-mers (one per line) or upload a text file. We support k=16, k=17, and k=18 (one length per request) and return composition stats.

Plain text; one k-mer per line.

Minimum Hamming distance

Optional. Reports whether the queried barcode is at least this many substitutions away from matched same-length sequences.

Optional sequence filters Off

Optional sequence-level filters can flag or exclude barcodes containing simple short motifs such as homopolymer runs, low-complexity repeats, common restriction enzyme sites, and selected functional-like motifs. These filters do not guarantee functional neutrality and are not organism-specific. For exact k-mer lookup, filters only annotate the queried sequence — they do not alter the present/absent result.

Motif mode

For exact lookup, "Exclude" annotates sequences that would be excluded from candidate outputs but does not hide the lookup result.

Filter homopolymers Max run length:

Filter low-complexity sequences Min Shannon entropy:

Filter dinucleotide repeats

Filter trinucleotide repeats

Filter tetranucleotide repeats

Filter custom sequence motif

Filter common restriction sites 50 sites

Check individual sites to filter. Unchecked means all sites are used when the parent checkbox is checked.

Flag short functional-like motifs 25 motifs

These are conservative sequence patterns, NOT organism-specific annotations. Check individual motifs to filter.