1. Open a Terminal, and launch following command to install Python3 from Apple:

xcode-select --install

A new window will appear asking about install Developer Tools for macOS. Click on Install.

NOTE: If your macOS is too old and installing Python3 from Xcode is not possible, install it directly from Python3 Official Download

2. Next, update pip (Python package manager) and install ESPTool:

python3 -m pip install --upgrade pip
python3 -m pip install esptool

3. In order to launch esptool.py, exec directly with this:

python3 -m esptool

Alternatively, but not needed, you can add Python binaries directory to PATH:

~/Library/Python/3.9/bin

To update a current installation of ESPTool to last version:

python3 -m pip install --upgrade esptool

python3 -m pip list

python3 -m pip list --outdated

python3 -m pip install --upgrade pip

python3 -m pip --disable-pip-version-check list --outdated --format=json | python3 -c "import json, sys; print('\n'.join([x['name'] for x in json.load(sys.stdin)]))" | xargs -n1 python3 -m pip install --upgrade