Webmerge Python API Docs | dltHub

Build a Webmerge-to-database pipeline in Python using dlt with AI Workbench support for Claude Code, Cursor, and Codex.

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Webmerge is a document automation platform that merges data into PDFs and other formats via a REST API. The REST API base URL is https://www.webmerge.me/api and All requests require HTTP Basic authentication with an API Key and Secret..

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 Webmerge data in under 10 minutes.


What data can I load from Webmerge?

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

ResourceEndpointMethodData selectorDescription
documents/documentsGETRetrieves a list of all documents in the account
document_detail/documents/GETRetrieves details of a specific document
document_fields/documents//fieldsGETRetrieves the list of fields for a specific document
routes/routesGETRetrieves a list of all routes (merged document templates)
route_detail/routes/GETRetrieves details of a specific route
route_fields/routes//fieldsGETRetrieves the fields defined for a specific route
document_file/documents//fileGETRetrieves the generated file (PDF) for a document
document_deliveries/documents//deliveriesGETRetrieves delivery history for a document

How do I authenticate with the Webmerge API?

Authentication uses HTTP Basic auth where the API Key is the username and the Secret is the password, passed in the Authorization header of each request.

1. Get your credentials

  1. Log in to your Webmerge account.
  2. Navigate to the Account page (usually under Settings).
  3. Locate the "API Keys" section.
  4. Click "Create New API Key".
  5. Copy the generated API Key and its associated Secret; store them securely.
  6. Use these credentials for HTTP Basic authentication as described in the auth_info.

2. Add them to .dlt/secrets.toml

[sources.webmerge_source] api_key = "your_api_key_here" api_secret = "your_api_secret_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:

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

1. Install the dlt AI Workbench:

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:

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 Webmerge 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:

python webmerge_pipeline.py

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

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

Inspect your pipeline and data:

dlt pipeline webmerge_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 documents and routes from the Webmerge API into DuckDB. It mirrors the endpoint and data selector configuration from the table above:

import dlt from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources @dlt.source def webmerge_source(api_key=dlt.secrets.value): config: RESTAPIConfig = { "client": { "base_url": "https://www.webmerge.me/api", "auth": { "type": "http_basic", "api_key": api_key, }, }, "resources": [ {"name": "documents", "endpoint": {"path": "documents"}}, {"name": "routes", "endpoint": {"path": "routes"}} ], } yield from rest_api_resources(config) def get_data() -> None: pipeline = dlt.pipeline( pipeline_name="webmerge_pipeline", destination="duckdb", dataset_name="webmerge_data", ) load_info = pipeline.run(webmerge_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):

import dlt data = dlt.pipeline("webmerge_pipeline").dataset() sessions_df = data.documents.df() print(sessions_df.head())

SQL (DuckDB example):

SELECT * FROM webmerge_data.documents LIMIT 10;

In a marimo or Jupyter notebook:

import dlt data = dlt.pipeline("webmerge_pipeline").dataset() data.documents.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 Webmerge data to?

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

DestinationExample value
DuckDB (local, default)"duckdb"
PostgreSQL"postgres"
BigQuery"bigquery"
Snowflake"snowflake"
Redshift"redshift"
Databricks"databricks"
Filesystem (S3, GCS, Azure)"filesystem"

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


Troubleshooting

Authentication errors

  • 401 Unauthorized – Occurs when the API Key or Secret is missing, malformed, or invalid. Ensure the credentials are correct and included using HTTP Basic authentication.

Rate limiting

  • Webmerge does not explicitly document rate limits, but if a 429 Too Many Requests response is received, back off for a short period before retrying.

Pagination

  • The current API responses return full result sets; no pagination parameters are documented. If large result sets become an issue, consider filtering via query parameters if they become available in future updates.

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

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