NEW in BLAST! We made smaller nucleotide databases to help you find the sequences you need faster and easier. You can now find these databases on the main nucleotide BLAST search page (Figure 1) and even download them (Databases: nt_euk, nt_prok, nt_viruses, nt_others). They are separated by organism type, such as eukaryotes, prokaryotes, viruses, and others (including synthetic sequences). 
Figure 1. The database selection section of the main nucleotide BLAST page with the ‘Experimental databases’ radio button selected. You can choose one or more of the organism database subsets for your search.
Features & Benefits
- Focus your search on relevant sequences
- Download these smaller databases faster
- Search for nucleotide sequences quickly
- Search two or more of these databases at the same time
Stay up to date
BLAST is a part of the NIH Comparative Genomics Resource (CGR). CGR facilitates reliable comparative genomics analyses for all eukaryotic organisms through an NCBI Toolkit and community collaboration.
Follow us on Twitter @NCBI and join our mailing list to keep up to date with BLAST and other CGR news.
We want to hear from you!
Thank you to those who tried out the test page and provided feedback.
If you haven’t already, try out our new databases and let us know what you think. If you have questions or would like to provide feedback, please reach out to us at info@ncbi.nlm.nih.gov.