DNA / RNA Sequence Generator
Generate random DNA or RNA sequences with a target GC content, or convert an input strand — complement, reverse complement, transcribe (DNA→RNA) and reverse transcribe. Outputs plain text or FASTA with base-composition stats.
Input
Generation Settings
Target percentage of G and C bases in the generated sequence
Output Settings
Wrap output at this column (0 = no wrap)
Output
Statistics
| Property | Value |
|---|---|
| No data yet | |
Guides
The DNA / RNA Sequence Generator creates random nucleotide sequences with a target GC content and transforms strands you already have. It is a quick, browser-based bench tool for building test data, teaching molecular biology, priming bioinformatics pipelines, or sanity-checking a strand by hand — no installs, no accounts.
What it does
Pick an Operation and the form adapts:
- Generate Random DNA / RNA — produces one or many sequences of a chosen length. Set the GC Content % target and the generator lays down exactly that share of G/C bases before shuffling them into a random order (RNA uses U in place of T). Optionally sprinkle in IUPAC ambiguity codes (R, Y, S, W, K, M, N) to mimic degenerate primers or uncertain calls.
- Complement — pairs each base with its Watson–Crick partner (A↔T, G↔C; A↔U for RNA).
- Reverse Complement — the complement read 3′→5′, i.e. the opposite strand as it would actually be written.
- Transcribe (DNA → RNA) — swaps every T for U.
- Reverse Transcribe (RNA → DNA) — swaps every U for T.
Every run also reports base composition: sequence count, total length, GC content, AT/AU content, and a per-base tally.
How to use it
- Choose an operation. For the convert modes, paste a sequence into Input Sequence — FASTA header lines, whitespace, and digits are stripped automatically, and letters are upper-cased.
- For generate modes, set the length, GC target, and how many sequences you want.
- Choose Plain Text or FASTA output. FASTA adds a
>prefix_N length=…header per sequence; the Line Wrap setting folds long strands at a fixed column (60 is the FASTA convention; set 0 to disable). - Click Generate. Copy the result or download it as a
.fastafile.
FAQ
How is the GC content applied?
The generator places the exact number of G/C bases implied by your percentage, then Fisher–Yates shuffles the whole sequence so the GC bases are randomly distributed. Enabling IUPAC codes overwrites a few positions afterward, so the realized GC percentage in the stats table can drift slightly from the target — the stats always reflect the actual output.
What is the difference between complement and reverse complement?
The complement pairs each base in place. The reverse complement pairs each base and reverses the order, which is how the opposite strand is conventionally written (5′→3′). Reverse complement is what you usually want when designing a primer or looking at the antisense strand.
Does it validate that my input is real DNA or RNA?
It normalizes case and removes whitespace, digits, and FASTA headers, then maps each character through the complement/transcription tables. Unrecognized characters complement to N rather than failing, so you can paste messy data without an error.
Is there a size limit?
Generated sequences run up to 10,000 bp each, up to 50 at a time. Conversions have no fixed cap beyond your browser's memory.
Privacy
This tool runs entirely in your browser. Sequences you paste or generate are never uploaded — nothing leaves your device, which makes it safe for unpublished or proprietary sequence data.