Random DNA Sequence Generator
Molecule
1–1000 bases
Every base is drawn with secure browser randomness (crypto.getRandomValues). Nothing is uploaded — the sequence, the FASTA text, and the download are all built on your device.
Random DNA and RNA sequences
Generate a random nucleotide sequence of any length from 1 to 1,000 bases. DNA draws from A, C, G, and T; flip the toggle to RNA to swap thymine (T) for uracil (U). Each position is an independent, uniform pick, so no base or motif is favoured — handy for primer and alignment test data, teaching examples, and placeholder sequences in bioinformatics coursework.
Copy or export as FASTA
Copy the raw bases, copy a ready-to-paste FASTA record (a >random_sequence_len header with the sequence wrapped at 60 columns), or download the same record as a .fasta file. Everything runs client-side with the Web Crypto API, so the sequence is unpredictable and never leaves your browser.