@langwatch/n8n-nodes-langwatch

This is an n8n community node. It lets you use LangWatch in your n8n workflows.

LangWatch is an LLM observability platform that provides tracing, evaluation, datasets, and prompt management.

n8n is a fair-code licensed workflow automation platform.

🚀 Recommended: Pair with Observability

For complete LangWatch integration, pair these nodes with @langwatch/n8n-observability to automatically trace your n8n workflows:

Quick setup for self-hosted n8n via npm:

npm install -g @langwatch/n8n-observability
export EXTERNAL_HOOK_FILES=$(node -e "console.log(require.resolve('@langwatch/n8n-observability/hooks'))")
export N8N_OTEL_SERVICE_NAME=my-n8n
n8n start

Table of Contents

• Installation
• Operations
• Credentials
• Development
• Resources

Installation

Self-hosted n8n

Follow the installation guide in the n8n community nodes documentation.

npm install @langwatch/n8n-nodes-langwatch

n8n Cloud

This is a verified community node. Search for LangWatch to use this node in n8n Cloud.

Operations

Dataset Batch Trigger

Emit one item per dataset row sequentially until done. Optionally initializes an experiment context for batch evaluations.

Key parameters:

• Dataset Slug or ID
• Experiment Configuration (enable, ID/Slug, Name, Workflow ID)
• Row Processing Options: startRow, endRow, stepSize, limitRows/maxRows, shuffleRows/seed
• Emit Interval (ms)

Output fields:

• entry (your dataset row payload)
• row_number, row_id, datasetId, projectId, timestamps
• _progress { current, total, percentage, remaining }
• _langwatch.dataset { id, rowId, rowNumber }
• _langwatch.experiment and _langwatch.batch when experiment is enabled

Dataset Row Trigger

Fetch a single dataset row per execution while maintaining an internal cursor. Great for stepwise or scheduled processing.

Key parameters:

• Dataset Slug or ID
• Row Processing Options: startRow, endRow, stepSize, limitRows/maxRows
• Reset Progress, Shuffle Rows, Shuffle Seed

Evaluation

Run evaluators and/or record results with multiple operation modes.

Operations:

• Auto (Recommended) - automatically selects behavior based on inputs
• Check If Evaluating - determines if running in evaluation context
• Record Result - log a pre-computed evaluation result
• Run and Record - execute an evaluator and log results
• Set Outputs (Dataset) - write entries back to a dataset

Key parameters:

• Run ID (optional override; otherwise inferred from _langwatch.batch.runId)
• Evaluator selection (manual or dropdown)
• Name, Evaluation Data, Evaluator Settings
• Guardrail flags: asGuardrail, failOnFail
• Dataset write: datasetSlug, format (standard/custom), mapping fields

Prompt

Retrieve and optionally compile a prompt from LangWatch Prompt Manager.

Key parameters:

• Prompt selection: Manual (handle/ID) or Dropdown
• Version selection: Latest or Specific version
• Compile Prompt: Off/On
• Variable Source: Manual, From Input Data, or Mixed
• Strict Compilation: fail if required variables are missing

Variables:

• Manual variables: list of name/value pairs (supports n8n expressions)
• Input data variables: map template variable → input data path

Credentials

To use this node, you need to authenticate with LangWatch. You'll need:

1. A LangWatch account at app.langwatch.ai
2. API credentials from your LangWatch project settings: hostname and API key

How to create:

1. In n8n, open Settings → Credentials → New
2. Pick "LangWatch API"
3. Fill endpoint and API key → Save → Test

Development

Prerequisites

You need the following installed on your development machine:

• git
• Node.js and npm. Minimum version Node 20. You can find instructions on how to install both using nvm (Node Version Manager) for Linux, Mac, and WSL here. For Windows users, refer to Microsoft's guide to Install NodeJS on Windows.
• Install n8n with:

  npm install n8n -g

• Recommended: follow n8n's guide to set up your development environment.

Build new version

npm run build
npm link

Test in local n8n

cd ~/.n8n/custom
npm link n8n-nodes-langwatch

Resources

• n8n community nodes documentation
• LangWatch documentation
• LangWatch n8n integration
• LangWatch Datasets
• LangWatch Prompts
• LangWatch n8n Observability - for workflow instrumentation

License

MIT