The main functionality of cached-path is provided by the function cached_path().

from cached_path import cached_path

Basic usage

cached_path() has a single positional argument that is either the path to a local file or the URL of a remote resource.

For example, assuming the file README.md exists locally, the returned by is just the same path that was provided:

assert cached_path("README.md") == "README.md"

But for remote resources, the resource will be downloaded and cached to the cache directory:

path = cached_path("https://github.com/allenai/cached_path/blob/main/README.md")
assert os.path.exists(path)
assert os.path.split(path)[0] == os.path.expanduser("~/.cache/cached_path")


There are multiple ways to change the cache directory.

If you were to call this again after the ETag of the resource has changed, a new version will be cached:

path2 = cached_path("https://github.com/allenai/cached_path/blob/main/README.md")
assert path2 != path

Supported URL schemes

In addition to http and https, cached_path() supports several other schemes such as s3 (AWS S3), gs (Google Cloud Storage), and hf (HuggingFace Hub). For a full list of supported schemes and examples, check the API documentation.

You can also overwrite how any of these schemes are handled or add clients for new schemes with the add_scheme_client method.

Working with archives

cached_path() will safely extract archives (.tar.gz or .zip files) if you set the extract_archive argument to True:

cached_archive = cached_path(
assert os.path.isdir(cached_archive)

This works for both local and remote resources.

You can also automatically get the path to a certain file or directory within an archive by appending an exclamation mark “!” followed by the relative path to the file within the archive to the string given to cached_path():

path = cached_path(
assert os.path.isfile(path)

Overriding the default cache directory

There are several ways to override the default cache directory that cached_path() stores cached resource versions to:

  1. Set the environment variable CACHED_PATH_CACHE_ROOT.

  2. Call set_cache_dir().

  3. Set the cache_dir argument each time you call cached_path().