Lob Python API Docs | dltHub

Lob is a cloud API platform for printing and mailing physical mail (postcards, letters, checks), address verification, bank account verification, and related direct-mail services. The REST API base URL is https://api.lob.com/v1 and all requests require HTTP Basic auth using your API key as the username (password blank).

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 pip install "dlt[workspace]" and start loading Lob data in under 10 minutes.

---

What data can I load from Lob?

Here are some of the endpoints you can load from Lob:

---

How do I authenticate with the Lob API?

Lob uses HTTP Basic authentication. Supply your API key as the username and leave the password empty; with curl you can pass -u <API_KEY>: . Requests not properly authenticated return 401.

1. Get your credentials

1. Sign in to Lob dashboard (https://dashboard.lob.com). 2) Go to Settings -> API Keys. 3) Copy the Test API key (prefixed test_...) for development or Live API key (live_...) for production. 4) Place the key in your dlt secrets toml as api_key = "..." and use it in the source.

2. Add them to .dlt/secrets.toml

Copy
[sources.lob_source]
api_key = "test_your_api_key_here"

dlt reads this automatically at runtime — never hardcode tokens in your pipeline script. For production environments, see setting up credentials with dlt for environment variable and vault-based options.

---

How do I set up and run the pipeline?

Set up a virtual environment and install dlt:

Copy
uv venv && source .venv/bin/activate
uv pip install "dlt[workspace]"

1. Install the dlt AI Workbench:

Copy
dlt 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
dlt ai toolkit rest-api-pipeline install

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 Lob 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
python lob_pipeline.py

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

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

Inspect your pipeline and data:

Copy
dlt pipeline lob_pipeline 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 addresses and postcards from the Lob 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 lob_source(api_key=dlt.secrets.value):
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://api.lob.com/v1",
            "auth": {
                "type": "http_basic",
                "api_key": api_key,
            },
        },
        "resources": [
            {"name": "addresses", "endpoint": {"path": "addresses", "data_selector": "data"}},
            {"name": "postcards", "endpoint": {"path": "postcards", "data_selector": "data"}}
        ],
    }
    yield from rest_api_resources(config)


def get_data() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="lob_pipeline",
        destination="duckdb",
        dataset_name="lob_data",
    )
    load_info = pipeline.run(lob_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("lob_pipeline").dataset()
sessions_df = data.addresses.df()
print(sessions_df.head())

SQL (DuckDB example):

Copy
SELECT * FROM lob_data.addresses LIMIT 10;

In a marimo or Jupyter notebook:

Copy
import dlt

data = dlt.pipeline("lob_pipeline").dataset()
data.addresses.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 Lob 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.

---

Troubleshooting

Authentication failures

Ensure you use HTTP Basic auth: the API key must be provided as the username and the password must be blank. A malformed or missing key returns HTTP 401 with an authentication error.

Rate limiting

Default rate limit: 150 requests per 5 seconds per endpoint (some endpoints higher). If you exceed the rate limit you will receive HTTP 429 with body: { "error": { "message": "Rate limit exceeded. Please wait 5 seconds and try your request again.", "code": "rate_limit_exceeded", "status_code": 429 } } and headers X-Rate-Limit-Limit, X-Rate-Limit-Remaining, X-Rate-Limit-Reset.

Pagination

List endpoints return a list object with top-level keys: object:"list", data: [ ... ], next_url, previous_url, count. Follow next_url to page through results. Use the provided after/limit query parameters as documented.

Common API errors

• 400/422 BAD_REQUEST/INVALID: malformed or invalid input; response includes error message with details.
• 401: UNAUTHORIZED when auth missing/invalid.
• 403: FEATURE_LIMIT_REACHED or test-to-live restrictions if billing/payment required.
• 404: NOT_FOUND for missing resources or UNRECOGNIZED_ENDPOINT for wrong path.
• 409/422: CONFLICT when operation would create a conflict.
• 429: rate_limit_exceeded (see Rate limiting).
• 5xx: INTERNAL_SERVER_ERROR/SERVICE_UNAVAILABLE on Lob side; retry recommended.

Ensure that the API key is valid to avoid 401 Unauthorized errors. Also, verify endpoint paths and parameters to avoid 404 Not Found errors.

---

Next steps

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

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

Copy
dlt ai toolkit data-exploration install
dlt ai toolkit dlthub-runtime install

• 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