The Exelixis Lab

Enabling Research in Evolutionary Biology

ExaML: Exascale Maximum Likelihood

About ExaML

Exascale Maximum Likelihood (ExaML) code for phylogenetic inference on supercomputers using MPI. This code implements the popular RAxML search algorithm for maximum likelihood based inference of phylogenetic trees. It uses a radically new MPI parallelization approach that yields improved parallel efficiency, in particular on partitioned multi-gene or whole-genome datasets. It is up to 3.2 times faster than RAxML-Light. As RAxML-Light, ExaML also implements checkpointing, SSE3, AVX vectorization and memory saving techniques. For further details please read the respective papers:

  • Paper describing the initial parallelization.
  • Paper describing the latest production level version of ExaML.

Citing ExaML

When using ExaML please cite it as follows:

Alexey M. Kozlov, Andre J. Aberer, Alexandros Stamatakis: "ExaML Version 3: A Tool for Phylogenomic Analyses on Supercomputers." In Bioinformatics 2015, doi: 10.1093/bioinformatics/btv184.

Latest code download

Get the most up-to-date ExaML version from github.


A user manual is provided with the source code repository.

User Support

Please send all your questions and feature request regarding ExaML to the RAxML google group. Before posting, keep in mind that a google group actually has a search function! Emails to Exelixis lab members regarding RAxML will not be answered. Messages posted via github will also not be answered.