Sprai (single-pass read accuracy improver) is a tool to correct sequencing errors in single-pass reads for de novo assembly. It is originally designed for correcting sequencing errors in single-molecule DNA sequencing reads, especially in Continuous Long Reads (CLRs) generated by PacBio RS sequencers. The goal of Sprai is not maximizing the accuracy of error-corrected reads; instead, Sprai aims at maximizing the continuity (i.e., N50 contig length) of assembled contigs after error correction.