> ## Documentation Index > Fetch the complete documentation index at: https://proto.evodesign.org/docs/llms.txt > Use this file to discover all available pages before exploring further. # Mutagenesis > Random sequence mutagenesis at nucleotide and protein levels Generate random sequence variants for directed-evolution libraries and robustness testing. These tools fill chosen positions with random residues drawn from configurable schemes, using standard nucleotide substitution rules for DNA and codon-based sampling for proteins. They provide a model-free baseline for exploring sequence space. * **Input:** a starting sequence and the positions to vary (or a target mutation rate). * **Output:** a library of randomized sequence variants drawn from the chosen substitution scheme.

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