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Codon Optimizer
Paste an amino acid sequence and get back a DNA sequence tailored for human cells. Codons are picked using real frequency data from the Kazusa database, so every run gives you a slightly different — but always valid — result.
Input Sequence
Enter your amino acid sequence in FASTA format or as raw text. Valid characters: A, C, D, E, F, G, H, I, K, L, M, N, P, Q, R, S, T, V, W, Y, * (stop)
How It Works
Why not just pick the “best” codon every time? Because real cells don’t work that way. This tool uses weighted random selection based on how often each codon actually appears in human genes:
- Reduces repetitive stretches that can trip up DNA synthesis
- Produces more natural-looking sequences
- Trends toward typical human GC content (~52%)
- Each run gives you a different valid sequence — try it a few times!
Where does the data come from? Codon frequencies are from the Kazusa Codon Usage Database for Homo sapiens, based on the entire human genome.