COInr a comprehensive, non-redundant COI database from NCBI-nt and BOLD

COInr is a non-redundant, comprehensive database of COI sequences extracted from NCBI-nt and BOLD. It is not limited to a taxon, a gene region, or a taxonomic resolution. Sequences are dereplicated between databases and within taxa.

Each taxon has a unique taxonomic Identifier (taxID), fundamental to avoid ambiguous associations of homonyms and synonyms in the source database. TaxIDs form a coherent hierarchical system fully compatible with the NCBI taxIDs allowing creating their full or ranked linages.
 
COInr is a good starting point to create custom databases according to the users’ needs using mkCOInr scripts available at https://github.com/meglecz/mkCOInr  
It is possible to select/eliminate sequences for a list of taxa, select a specific gene region, select for minimum taxonomic resolution, add new custom sequences, and format the database for BLAST, QIIME, RDP classifiers.