Welcome to ChemEx

Quick Overview

ChemEx is a powerful tool for analyzing NMR experimental data to characterize chemical exchange processes. This guide will help you get started with ChemEx, from installation to initial usage. ChemEx is designed to support experiments like Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion and Chemical Exchange Saturation Transfer (CEST).

Prerequisites

ChemEx requires Python 3.13 or later. When a requested ChemEx release needs a newer Python, uv can use a compatible installed interpreter or download a managed one when automatic Python downloads are enabled (the default).

Installation

PyPI is the authoritative Python package distribution for ChemEx.

Recommended installation

uv installs ChemEx as an application in an isolated environment. On macOS, install uv with Homebrew:

brew install uv

On Linux or Windows, follow Astral's current uv installation instructions.

Then install ChemEx from PyPI and verify that it starts:

uv tool install chemex@latest
chemex --version

Requesting @latest prevents uv from selecting an older ChemEx release to match an outdated Python interpreter.

Try ChemEx without installing it

uvx chemex@latest --help

Updating ChemEx

Update an unpinned tool installation with:

uv tool upgrade chemex

Reproducible, version-pinned installation

To install a specific release:

uv tool install "chemex==2026.09.1"

Alternative: pip

If you need conventional Python tooling, use Python 3.13 or later to install ChemEx from PyPI inside a virtual environment:

python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
python -m pip install chemex

Conda packages

The historical conda-forge package is no longer maintained by the ChemEx project and may be outdated. Install the current PyPI release with uv or pip.

Next step

With ChemEx installed, run your first ChemEx analysis: a real two-field ¹⁵N CPMG chemical-exchange fit with generated parameters and dispersion plots.