+The Crates lister list origins from `Crates.io`_, the Rust community’s crate registry.
+
+Origins are `packages`_ for the `Rust language`_ ecosystem.
+Package follow a `layout specifications`_ to be usable with the `Cargo`_ package manager and have a `Cargo.toml`_ file manifest which consists in metadata to describe and build a specific package version.
+
+As of August 2022 `Crates.io`_ list 89013 packages name for a total of 588215 released versions.
+
+Origins retrieving strategy
+---------------------------
+
+A json http api to list packages from crates.io but we choose a `different strategy`_ in order to reduce to its bare minimum the amount of http call and bandwidth.
+We clone a git repository which contains a tree of directories whose last child folder name corresponds to the package name and contains a Cargo.toml file with some json data to describe all existing versions of the package.
+It takes a few seconds to clone the repository and browse it to build a full index of existing package and related versions.
+The lister is incremental, so the first time it clones and browses the repository as previously described then stores the last seen commit id.
+Next time, it retrieves the list of new and changed files since last commit id and returns new or changed package with all of their related versions.
+
+Note that all Git related operations are done with `Dulwich`_, a Python implementation of the Git file formats and protocols.
+
+Page listing
+------------
+
+Each page is related to one package.
+Each line of a page corresponds to different versions of this package.
+
+The data schema for each line is:
+
+* **name**: Package name
+* **version**: Package version
+* **crate_file**: Package download url
+* **checksum**: Package download checksum
+* **yanked**: Whether the package is yanked or not
+* **last_update**: Iso8601 last update date computed upon git commit date of the related Cargo.toml file
+
+Origins from page
+-----------------
+
+The lister yields one origin per page.
+The origin url corresponds to the http api url for a package, for example "https://crates.io/api/v1/crates/{package}".
+
+Additionally we add some data set to "extra_loader_arguments":
+
+* **artifacts**: Represent data about the Crates to download, following :ref:`original-artifacts-json specification <extrinsic-metadata-specification#original-artifacts-json>`
+* **crates_metadata**: To store all other interesting attributes that do not belongs to artifacts. For now it mainly indicate when a version is `yanked`_.