Reverse Complement Reverse complement

Free DNA sequence tool

Reverse Complement DNA

Paste a sequence or FASTA record. Results update as you type, and nothing leaves your browser.

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Paste a DNA sequence or FASTA record to begin.

How It Works

  • Reverse complement swaps each base for its pair (A↔T, G↔C) and reverses the order, giving the opposite strand read 5′→3′.
  • Case is preserved, so aTg becomes cAt. N stays N.
  • Only G A T C N are kept. Spaces, numbers, gaps, IUPAC ambiguity codes and RNA U are removed, and a note explains what changed.
  • A FASTA header line (>title) is removed and shown in the results line. Convert one record at a time.
  • By default the result is one unwrapped line. Line width changes how it is shown, copied and downloaded. Base colouring only changes how it is shown.

Base colour key

A T G C N

Shown when “Colour bases” is on. The hues stay distinct for common types of colour blindness, and the letters are always visible too.

Output matches the Reverse Complement tool in the Sequence Manipulation Suite by Paul Stothard.