Download

A single 64-bit Linux executable with no build step. Pick the build for your distribution, add the data folder, and you are running.

Version 5.3.9
Released 2026-09-16
Platform Linux x86-64
Language C++

Choose your build

All three are the same IChem 5.3.9, built on different distributions. They differ only in how new a system library they expect — if you are unsure, the Red Hat build is the most forgiving.

Debian
IChem_debian
5.5 MB · ELF 64-bit PIE

Built on Debian 12 (bookworm). Needs glibc 2.34 and GLIBCXX 3.4.29, so it runs on Debian 12 and newer. Too new for Debian 11 (bullseye).

Download for Debian
Ubuntu
IChem_ubuntu
5.5 MB · ELF 64-bit PIE

Built on Ubuntu. Needs glibc 2.34 and GLIBCXX 3.4.29, so it runs on Ubuntu 22.04 LTS and newer. Too new for 20.04 LTS, which ships glibc 2.31.

Download for Ubuntu
Red Hat
IChem_ubi
4.0 MB · ELF 64-bit

Built on the Red Hat Universal Base Image. Needs only glibc 2.14 and GLIBCXX 3.4.22, which makes it the most portable of the three: RHEL, Rocky, Alma and CentOS Stream 8 and 9, and most other distributions from 2017 onwards.

Download for Red Hat
Where these come from All three binaries are published on the project's GitHub releases page, built automatically from the tagged source. The buttons above link straight to them, so you always get the file GitHub serves rather than a copy of it. Whichever you take, remember to chmod +x it.

And you will also need

Required
Data folder
42.7 MB · tar.gz

The HET dictionary, pharmacophore rule tables and roughly 22 000 ligand templates that IChem reads at run time. Unpacks to lib/, which ICHEM_LIB must point at. Without it, pdbconv and the druggability model cannot run.

Download data folder
Optional
Tutorial dataset
2.1 MB · tar.gz

Every input file used in the tutorials, plus reference outputs to check your installation against. Unpacks to dataset/test/. You can also browse the files directly.

Download dataset
Source
Source code
C++20 · CMake

IChem is developed in the open. The repository holds the full source, the data folder, the regression test suite, and the changelog. Build it yourself for a platform none of the three binaries covers, or for the optional Python bindings.

View on GitHub

Which build do I need?

Every IChem build is dynamically linked against the system C and C++ runtimes, so the only question is whether yours is new enough. These are the versions each binary actually requires:

Buildglibclibstdc++Runs on
IChem_debian 2.34+ GLIBCXX 3.4.29 (GCC 11+) Debian 12 and newer
IChem_ubuntu 2.34+ GLIBCXX 3.4.29 (GCC 11+) Ubuntu 22.04 LTS and newer
IChem_ubi 2.14+ GLIBCXX 3.4.22 (GCC 6.1+) RHEL / Rocky / Alma 8 and 9, and most distributions from 2017 on

Check what your machine has before downloading: 

ldd --version | head -1
ldd (GNU libc) 2.34
strings /usr/lib64/libstdc++.so.6 | grep -o 'GLIBCXX_[0-9.]*' | sort -uV | tail -1
GLIBCXX_3.4.29

On Debian and Ubuntu the library sits in /usr/lib/x86_64-linux-gnu/ rather than /usr/lib64/. Architecture is x86-64 throughout; there is no 32-bit or ARM build. Budget about 320 MB of disk once the data folder is unpacked, or 330 MB with the tutorial dataset as well.

If none of them fit A binary that is too new for your system fails at startup with version `GLIBC_2.34' not found rather than misbehaving later, so the wrong choice is obvious and harmless. Try the Red Hat build first; if that also refuses, build from source — the repository uses CMake and C++20, and that is also the route to the Python module.

Verify your download

The release publishes a checksum file alongside the binaries. Worth a moment, since you are about to mark this file executable: 

curl -LO https://github.com/LIT-CCM-lab/IChem/releases/download/v5.3.9/SHA256SUMS.txt
sha256sum --ignore-missing -c SHA256SUMS.txt
IChem_ubi: OK

Or compare by eye against the published values:

FileSHA-256
IChem_debian 40db64cb6b9494cc2bb9d46ba1bb73f4133eb05f005f82d1887b23558db3a985
IChem_ubi 808134e55495c99ff2e2d87d7dccbcf626c8161ca22956172b78598a0bbfd755
IChem_ubuntu b4e986e2ee728e5d7486d9681502dc62a6c633992528ec770be347d7f6cff120

Install in four commands

# 1. put the files you downloaded in one place
mkdir -p ~/IChem && cd ~/IChem

# 2. give your build its working name and make it runnable
#    (swap IChem_ubi for IChem_debian or IChem_ubuntu)
mv IChem_ubi IChem && chmod +x IChem

# 3. unpack the data folder (creates ./lib)
tar xzf IChem_lib.tar.gz

# 4. point IChem at it
export ICHEM_LIB="$PWD/lib"
export PATH="$PWD:$PATH"

Check it worked: 

IChem | head -2
IChem Version : 5.3.9
Date : 2026-09-16

Put the two export lines in your shell start-up file so they persist. The installation guide covers the csh syntax, what each variable does, and how failures present themselves.

Verify your installation

The dataset ships reference outputs. Re-running a tutorial and diffing against them confirms the binary and the data folder agree with each other: 

cd "$ICHEM_DIR/dataset/test/REALIGN"
IChem --wMob realign GRIM_ints.mol2 4amj_INTS_M.mol2 4amj_lig.mol2 4amj_prot.mol2
diff <(grep -v "Modification time" rot_4amj_lig.mol2) \
     <(grep -v "Modification time" output/rot_4amj_lig.mol2) && echo OK
OK
Reference outputs and versions Some stored outputs were produced by earlier releases. realign, bsa, volsite and pdbconv reproduce them exactly; ints and grim do not, because 5.3.9 detects more hydrophobic contacts than the release those files came from. A difference there is expected, not a broken install.

Citing IChem

If IChem contributes to published work, please cite:

Da Silva, F., Desaphy, J. and Rognan, D. IChem: A Versatile Toolkit for Detecting, Comparing, and Predicting Protein–Ligand Interactions. ChemMedChem, 2018, 13, 507–510. DOI: 10.1002/cmdc.201700505

The Literature corner lists the papers behind each individual module.