Prinseq is a tool for quality control and preprocessing of genomic and metagenomic datasets. It provides summary statistics in tabular and graphical formats for FASTA or FASTQ files, and allows filtering, reformatting, and trimming of sequences to improve downstream analysis. The tool is available as a standalone application or through a user-friendly web interface. It can process compressed files and allows data sharing via unique identifiers. Prinseq evaluates sequence complexity using two methods: one based on the DUST algorithm and another using block-entropies. It also calculates dinucleotide odds ratios to detect contamination and tag sequence probabilities to identify adapter or barcode sequences. Sequence duplication is categorized into several types, and duplicates are identified through sorting and prefix/suffix matching. Prinseq offers features such as quality control, sequence filtering, trimming, formatting, and a web interface. It provides summary statistics including read length, GC content, quality scores, sequence complexity, and contamination. It also allows the identification of sequence duplicates and the calculation of assembly measures like N50 or N90. Prinseq can filter sequences based on length, quality, GC content, ambiguous bases, and sequence complexity. It allows trimming of sequences to specific lengths, removal of poly-A/T tails, and trimming by quality scores. It can also convert between FASTA and FASTQ formats. Prinseq is compared with other tools like SolexaQA, FastQC, and FASTX-Toolkit, which also provide quality control and preprocessing features. However, Prinseq offers a more comprehensive set of features and is user-friendly. It is suitable for both online and offline analysis and can be integrated into existing data processing pipelines. The tool is useful for checking the success of sequencing experiments and identifying contamination. It is a valuable resource for handling large datasets generated by next-generation sequencers.Prinseq is a tool for quality control and preprocessing of genomic and metagenomic datasets. It provides summary statistics in tabular and graphical formats for FASTA or FASTQ files, and allows filtering, reformatting, and trimming of sequences to improve downstream analysis. The tool is available as a standalone application or through a user-friendly web interface. It can process compressed files and allows data sharing via unique identifiers. Prinseq evaluates sequence complexity using two methods: one based on the DUST algorithm and another using block-entropies. It also calculates dinucleotide odds ratios to detect contamination and tag sequence probabilities to identify adapter or barcode sequences. Sequence duplication is categorized into several types, and duplicates are identified through sorting and prefix/suffix matching. Prinseq offers features such as quality control, sequence filtering, trimming, formatting, and a web interface. It provides summary statistics including read length, GC content, quality scores, sequence complexity, and contamination. It also allows the identification of sequence duplicates and the calculation of assembly measures like N50 or N90. Prinseq can filter sequences based on length, quality, GC content, ambiguous bases, and sequence complexity. It allows trimming of sequences to specific lengths, removal of poly-A/T tails, and trimming by quality scores. It can also convert between FASTA and FASTQ formats. Prinseq is compared with other tools like SolexaQA, FastQC, and FASTX-Toolkit, which also provide quality control and preprocessing features. However, Prinseq offers a more comprehensive set of features and is user-friendly. It is suitable for both online and offline analysis and can be integrated into existing data processing pipelines. The tool is useful for checking the success of sequencing experiments and identifying contamination. It is a valuable resource for handling large datasets generated by next-generation sequencers.