py-code-org

Find which PyPI packages use a module, function or class, from the command line or from an AI coding tool. It reads the index behind py-code.org, which covers the latest release of more than 335,000 PyPI projects (every project released in the last year, plus the most downloaded ones) and records every name their code imports or reaches by attribute.

Use it before you rename or remove something in a library, to see who calls it and where.

$ uvx py-code-org who-uses httpx.AsyncClient --limit 3
26,709 packages use httpx.AsyncClient (index built 2026-11-13)

#  Package                  Version  Downloads/mo  Files  First use
1  google-genai             3.2.0          124.9M      8  google/genai/_api_client.py:735
2  google-cloud-aiplatform  2.9.0           70.8M      3  agentplatform/_genai/_runtimes_utils.py:1810
3  sentry-sdk               2.75.0          66.7M      1  sentry_sdk/integrations/httpx.py:28

Showing 3 of 26,709. --limit 0 shows the 2,000 most downloaded.

Narrower names: httpx.AsyncClient.send (179), httpx.AsyncClient.__init__ (57), ...

It has no dependencies and needs Python 3.9 or newer.

Install

pipx install py-code-org     # or: uv tool install py-code-org

Or run it without installing: uvx py-code-org who-uses requests.Session.

Commands

Options:

• who-uses --min-downloads N: only packages with at least N downloads in the last 30 days.
• who-uses --limit N, names --limit N: rows to show; 0 shows all.
• names --prefix numpy.linalg: only names that start with the prefix.
• --json on every lookup command prints JSON for scripts.

Names are case-sensitive and written as the code imports them: requests.Session, numpy.linalg.norm, PIL.Image. When a name is not found, the tool suggests the closest indexed spelling. The exit code is 0 when found, 1 when not found and 2 when the index could not be reached.

Use it from an AI coding tool (MCP)

The mcp command gives AI coding tools three read-only tools:

• who_uses(name, min_downloads, limit)
• project_imports(project)
• module_names(module, prefix, limit)

Claude Code:

claude mcp add py-code -- uvx py-code-org mcp

Cursor, Claude Desktop and other tools that read an mcpServers JSON file:

{
  "mcpServers": {
    "py-code": { "command": "uvx", "args": ["py-code-org", "mcp"] }
  }
}

Then ask, for example: "Which popular packages call requests.Session.merge_environment_settings?"

Where the data comes from

Every lookup is two small requests to the static JSON files at https://data.py-code.org/api: a manifest, then the shard that holds the name. Nothing is sent except the name you look up. The index is rebuilt monthly. Set PY_CODE_API to read a copy hosted elsewhere.

What it misses: older releases, dynamic imports (importlib.import_module, getattr), names passed through variables, and files that do not parse as current Python. For bulk queries, the full tables are on Hugging Face as Parquet: pypi-data/py-code.

The scanner that builds the index is in the same repository: pypi-data/py-code.

Licence

MIT.