We present a browser-based curation tool developed to support expert validation of taxonomic records derived from the Barcode of Life Data System (BOLD). This tool forms a critical component of a two-step approach designed within the EU Horizon Europe project Biodiversity Genomics Europe (BGE) to build a high-quality, curated DNA barcode reference library for European species. The upstream component—a bioinformatics pipeline described in a companion publication—automatically filters, cleans, and ranks BOLD records based on metadata completeness, sequence quality, and taxonomic consistency. However, certain complex cases, such as misidentifications, nomenclatorial problems (e.g. synonymy), BIN-sharing (multiple species sharing one BIN) or BIN-splitting (a single species associated with multiple BINs), cannot be fully resolved by automated methods and require expert judgment.

Our curation tool enables taxonomic experts to interactively inspect, validate, or exclude individual records, update species names, assign curation statuses, and provide curator notes. The tool supports real-time statistics for BIN conflicts and dynamically updates curation metrics as the expert interacts with the data. Its user interface is designed to simplify the review of large datasets while ensuring consistency, traceability, and minimal risk of structural errors common in spreadsheet-based curation workflows.

The curated output from this tool, combined with the automated pipeline, forms the foundation of a reference library suitable for accurate DNA-based species identification in biodiversity monitoring and ecological studies. By integrating expert knowledge into a standardized and scalable interface, the tool supports the creation of FAIR, version-controlled reference libraries essential in the era of accelerating biodiversity loss and declining taxonomic capacity.