MotherDuck

MotherDuck is a managed, serverless cloud data warehouse built on top of DuckDB, offering fast, in-process SQL analytics without the need to manage any infrastructure.

What Weld supports

Weld integrates with MotherDuck in three ways:

• ELT destination — sync data from any of your Weld sources into MotherDuck. Weld supports append, merge and full-copy load strategies, and will automatically create and evolve destination tables (including adding new columns) as your source schemas change.
• Reverse-ETL / Activate source — use tables and views in MotherDuck as the source for Reverse-ETL syncs, so you can push data from MotherDuck out to your business tools.
• Data Warehouse querying — run ad-hoc SQL against MotherDuck from Weld's query builder and use it to power custom reports.

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🔧 Setup Guide

Weld connects to MotherDuck using a Service Token, which is a token you generate from the MotherDuck UI. A token is required — Weld runs headless in the background and cannot complete an interactive browser/SSO login, so connections without a token cannot be created.

1. Log in to your MotherDuck account.

2. Go to Settings → Tokens and create a new Service Token.

A Service Token is recommended over a personal access token, since it isn't tied to a specific user and won't expire when a team member leaves.

3. Copy the generated token — you'll need it in the next step.

4. In Weld, when adding a new MotherDuck connection, provide:

• Service Token — the token generated in step 2. Required.
• Database — the name of the MotherDuck database (catalog) to connect to. Optional — if left empty, Weld will connect to your default database.

5. Press Connect. Weld will validate the token by running a test query against MotherDuck.

Once connected, you can start syncing data into MotherDuck, use it as a source for Activate, or query it directly from Weld's query builder.