What is the Codon Finder?
Find and analyze codons in RNA or DNA sequences. Search for a specific triplet like AUG, list all codons in reading frames 1–3, or highlight start and stop codons only. See positions, amino acids, codon types, and frequency counts. Supports FASTA input. Free, private, and instant in your browser.
How to use the Codon Finder
- Paste an RNA or DNA sequence (T is converted to U).
- Choose all codons, search for one codon, or start/stop only.
- Select reading frame 1, 2, 3, or all frames.
- For search mode, enter a 3-letter codon such as AUG or UGA.
- Review positions, amino acids, and codon frequency chips.
Common use cases
- Locating all AUG start codons in an mRNA sequence
- Finding stop codons before predicting an ORF
- Counting codon usage in a reading frame
Frequently asked questions
- What is a codon?
- A codon is a three-nucleotide unit in mRNA that codes for one amino acid or a stop signal during translation.
- What is the start codon?
- AUG codes for methionine and usually marks where translation begins.
- What are stop codons?
- UAA, UAG, and UGA signal termination. They do not code for an amino acid.
- What does raw substring match mean?
- When searching for a codon, in-frame hits follow the reading frame. Raw matches count every occurrence of the three-letter pattern anywhere in the sequence, including out-of-frame overlaps.
- Is my sequence uploaded?
- No. All analysis runs locally in your browser.
