(requirements-txt-file)= # `requirements.txt` file The `requirements.txt` file is a standard Python [requirements file](https://pip.pypa.io/en/stable/reference/pip_install/#requirements-file-format) used to declare and pin the version of any Python libraries required by a charm in production. This will be pre-populated with [`ops`](https://ops.readthedocs.io/en/latest/). Any dependencies specified here will be bundled with the charm when it is built with {ref}`charmcraft pack `.