Load Lemlist data to DuckDB

lemlist is a sales engagement and email outreach platform that provides a REST API for managing campaigns, leads, and outreach activities. Everything needed to build a working Lemlist → DuckDB pipeline is on this page: the API's base URL, authentication, endpoints, pagination and incremental field — plus a prompt that hands the whole job to your coding agent.

---

Build your Lemlist to DuckDB pipeline

Paste this prompt into Claude, Codex, or Cursor. The agent does the rest.

PromptCopy prompt
Run uvx dlthub-init@latest to build a pipeline from Lemlist to DuckDB and run it on dltHub

That scaffolds a dltHub workspace and installs the dltHub AI harness — the project rules, the secrets-management skill, and the dlt MCP server your agent needs to work safely. From there it reads the Lemlist API, proposes the endpoints to load, then writes, runs and validates the pipeline while you review rather than type. Credentials are inspected through MCP tools, so your agent never reads secrets.toml itself. How the LLM-native workflow works →

Prefer to write it yourself? Every fact the agent uses is below.

---

Lemlist API at a glance

These values come from the Lemlist API reference — the authoritative source if anything here looks out of date.

---

How do I authenticate with the Lemlist API?

Authentication is performed using HTTP Basic authentication. The request must include an 'Authorization' header with the value 'Basic {base64_encoded_string}', where the string is ':YOUR_API_KEY' (a colon followed by the API key).

1. Get your credentials

1. Log in to your lemlist account at https://app.lemlist.com.
2. Click your profile picture in the bottom left-hand corner and select Settings.
3. Navigate to the Integrations tab.
4. Locate the API section and click Generate a new API key.
5. Copy and store the key securely, as it will not be displayed again. Authentication uses HTTP Basic Auth: the username is empty, and the password is your API key. Base64-encode the string ':YOUR_API_KEY' (note the leading colon) and include it in your request as 'Authorization: Basic <base64_encoded_string>'.

2. Add them to .dlt/secrets.toml

Copy
[sources.lemlist_source]
api_key = "your_api_key_here"

dlt reads this file automatically at runtime. With the harness, the setup-secrets skill prompts you for the values and never handles the raw credential in chat. For production, see setting up credentials with dlt.

---

What Lemlist data can I load into DuckDB?

These are the Lemlist endpoints dlt can load into DuckDB:

---

How do I load only new Lemlist records?

The Lemlist API reference does not document a timestamp or sequence field for these endpoints, so there is nothing to advertise here as verified. Pick a field from the endpoints table above that increases with every write, then set it as the cursor_path.

Copy
{"name": "campaigns", "endpoint": {
    "path": "campaigns",
    # Replace with a field that increases on every write.
    "incremental": {"cursor_path": "REPLACE_ME", "initial_value": "2024-01-01T00:00:00Z"},
}}

On the first run dlt loads everything from initial_value; on every run after that it requests only what changed and appends with write_disposition="merge" if you set a primary key. See incremental loading.

---

What does the generated Lemlist pipeline look like?

A standard dlt REST API pipeline — the same code you would write by hand, loading /campaigns and /leads from the Lemlist API into DuckDB:

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

@dlt.source
def lemlist_source(api_key=dlt.secrets.value):
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://api.lemlist.com/api",
            "auth": {"type": "http_basic", "username": "REPLACE_ME", "password": api_key},
        },
        "resources": [
            {"name": "campaigns", "endpoint": {"path": "campaigns"}},
            {"name": "campaign_leads", "endpoint": {"path": "campaigns/{campaignId}/leads"}}
        ],
    }
    yield from rest_api_resources(config)


def load_lemlist_to_duckdb() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="lemlist_pipeline",
        destination="duckdb",
        dataset_name="lemlist_data",
    )
    load_info = pipeline.run(lemlist_source())
    print(load_info)


if __name__ == "__main__":
    load_lemlist_to_duckdb()

Run it with python lemlist_pipeline.py. The agent iterates on this until it loads cleanly — you review and approve, rather than write it from scratch.

---

How do I query Lemlist data in DuckDB?

dlt creates one table per resource. Query the loaded data with Python or SQL — or ask your agent to, through the MCP server's execute_sql_query tool.

Python (pandas DataFrame):

Copy
import dlt

data = dlt.pipeline("lemlist_pipeline").dataset()
df = data.campaigns.df()
print(df.head())

SQL:

Copy
SELECT * FROM lemlist_data.campaigns LIMIT 10;

See querying your data with dataset and exploring it in marimo notebooks.

---

How do I deploy the Lemlist to DuckDB pipeline in production?

The pipeline runs locally, which is ideal for prototyping and one-off analysis. When you need it on a schedule, monitored on every load, and shared with your team, deploy the same dlt code on the dltHub platform — no infrastructure to maintain. The prompt above already ends with "run it on dltHub", so your agent can take it there directly.

• Deploy & schedule — run the pipeline as a managed job with automatic retries.
• Monitor — observable job queues, alerting, and load metrics for every run.
• Transform — promote raw Lemlist loads into governed, documented models.
• Visualize & share — explore data in notebooks and publish live dashboards instead of static screenshots.

Book a demo →

---

What other destinations can I load Lemlist data to?

dlt loads into any of these — only the destination argument changes:

Set dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. On the dltHub platform the same pipeline runs against a managed Iceberg lakehouse. See the full destinations list.

---

Next steps

• Ready for production? Book a demo of the dltHub platform →
• dlt LLM-native workflow docs
• REST API source reference
• Join the dlt community on Slack