UCSC Genome Browser

"The University of California Santa Cruz (UCSC) Genome Browser is an online resource for the genomics community providing data access and visualization, collaboration and support resources, and a suite of tools that are now standard in the field." Link

Link:  genome.ucsc.edu

Ensembl Genome Browser

"Ensembl is a genome browser for vertebrate genomes that supports research in comparative genomics, evolution, sequence variation and transcriptional regulation. Ensembl annotate genes, computes multiple alignments, predicts regulatory function and collects disease data. Ensembl tools include BLAST, BLAT, BioMart and the Variant Effect Predictor (VEP) for all supported species."

Link:  ensembl.org/index.html

NCBI Genome Data Viewer

"NCBI’s flagship genome browser, Genome Data Viewer (GDV) (https://www.ncbi.nlm.nih.gov/genome/gdv/), integrates the SV graphical display with a robust search/retrieval/analysis console. Users can view their own data next to NCBI tracks as references. "

Link:  ncbi.nlm.nih.gov/genome/gdv