CMS Data Python API Docs | dltHub

The CMS Data REST API provides access to the Centers for Medicare & Medicaid Services public data catalog for querying and downloading datasets in JSON or JSON

format. The REST API base URL is https://data.cms.gov/data-api/v1 and Public datasets are open and do not require authentication..

dlt is an open-source Python library that handles authentication, pagination, and schema evolution automatically. dlthub provides AI context files that enable code assistants to generate production-ready pipelines. Install with uv add "dlt[hub]" and start loading CMS Data data in under 10 minutes.

---

What data can I load from CMS Data?

Here are some of the endpoints you can load from CMS Data:

---

How do I authenticate with the CMS Data API?

Public data.cms.gov datasets do not require authentication or API keys.

No credentials required. The CMS Data API is public, so there is nothing to obtain and nothing to add to .dlt/secrets.toml — the pipeline above runs as written.

---

How do I set up and run the pipeline?

Set up a virtual environment and install dlt:

Copy
uv init
uv add "dlt[hub]"

1. Install the dlt AI harness:

Copy
uv run dlthub ai init --agent <your-agent> # <agent>: claude | cursor | codex

This installs project rules, a secrets management skill, appropriate ignore files, and configures the dlt MCP server for your agent. Learn more →

2. Install the rest-api-pipeline toolkit:

Copy
uv run dlthub ai toolkit install rest-api-pipeline

This loads the skills and context about dlt the agent uses to build the pipeline iteratively, efficiently, and safely. The agent uses MCP tools to inspect credentials — it never needs to read your secrets.toml directly. Learn more →

3. Start LLM-assisted coding:

Use /find-source to load data from the CMS Data API into DuckDB.

The rest-api-pipeline toolkit takes over from here — it reads relevant API documentation, presents you with options for which endpoints to load, and follows a structured workflow to scaffold, debug, and validate the pipeline step by step.

4. Run the pipeline:

Copy
uv run python cms_data_pipeline.py

If everything is configured correctly, you'll see output like this:

Copy
Pipeline cms_data_pipeline load step completed in 0.26 seconds
1 load package(s) were loaded to destination duckdb and into dataset cms_data_data
The duckdb destination used duckdb:/cms_data.duckdb location to store data
Load package 1749667187.541553 is LOADED and contains no failed jobs

Inspect your pipeline and data:

Copy
uv run dlthub show

This opens the Pipeline Dashboard where you can verify pipeline state, load metrics, schema (tables, columns, types), and query the loaded data directly.

---

Python pipeline example

This example loads /dataset/{uuid}/data and /dataset/{uuid}/data-viewer from the CMS Data API into DuckDB. It mirrors the endpoint and data selector configuration from the table above:

Copy
import dlt
from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources

@dlt.source
def cms_data_source():
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://data.cms.gov/data-api/v1",
        },
        "resources": [
            {"name": "dataset_data", "endpoint": {"path": "dataset/{uuid}/data"}},
            {"name": "data_catalog", "endpoint": {"path": "data.json", "data_selector": "resources"}}
        ],
    }
    yield from rest_api_resources(config)


def get_data() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="cms_data_pipeline",
        destination="duckdb",
        dataset_name="cms_data_data",
    )
    load_info = pipeline.run(cms_data_source())
    print(load_info)

To add more endpoints, append entries from the resource table to the "resources" list using the same name, path, and data_selector pattern.

---

How do I query the loaded data?

Once the pipeline runs, dlt creates one table per resource. You can query with Python or SQL.

Python (pandas DataFrame):

Copy
import dlt

data = dlt.pipeline("cms_data_pipeline").dataset()
sessions_df = data.dataset_data.df()
print(sessions_df.head())

SQL (DuckDB example):

Copy
SELECT * FROM cms_data_data.dataset_data LIMIT 10;

In a marimo or Jupyter notebook:

Copy
import dlt

data = dlt.pipeline("cms_data_pipeline").dataset()
data.dataset_data.df().head()

See how to explore your data in marimo Notebooks and how to query your data in Python with dataset.

---

What destinations can I load CMS Data data to?

dlt supports loading into any of these destinations — only the destination parameter changes:

Change the destination in dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. See the full destinations list.

---

Next steps

Continue your data engineering journey with the other toolkits of the dltHub AI harness:

• data-exploration — Build custom notebooks, charts, and dashboards for deeper analysis with marimo notebooks.
• dlthub-platform — Deploy, schedule, and monitor your pipeline in production.

Copy
uv run dlthub ai toolkit install data-exploration
uv run dlthub ai toolkit install dlthub-platform

• How to deploy a pipeline
• How to explore your data in marimo Notebooks
• How to query your data in Python with dataset
• Join the dlt community on Slack