Mailchimp Bulk List Merger

WHAT IT DOES

Mailchimp Bulk List Merger solves a common email marketing challenge: consolidating multiple Mailchimp audiences is tedious when done manually. Mailchimp provides no native way to merge lists, requiring you to export and import subscribers or use third-party tools. This tool reads your current Mailchimp audience list page, detects all visible audiences/lists, and displays them in a scrollable checklist with list names, subscriber counts, creation dates, and statuses. You select multiple source lists and choose a single target list to merge them into. The tool then processes each selected source list sequentially through Mailchimp's API, moving all subscribers to the target list and optionally archiving or deleting the empty source lists. A preview shows your selection before merging, and progress tracking shows each list as it's processed. You can choose to keep source lists as archived lists instead of deleting them permanently.

WHERE IT RUNS

This extension panel runs directly inside your browser as an overlay on any Mailchimp audience list page. It works on the audience management page where all your lists are displayed. The tool detects lists from the page's DOM and uses Mailchimp's official API (via GM_xmlhttpRequest) for merge operations. It requires no additional API keys beyond your existing authenticated session — the tool extracts your API key from the page.

HOW TO USE

After installing the BotGentz extension and activating Mailchimp Bulk List Merger, navigate to your Mailchimp audience list page. Click the extension icon in your browser toolbar to open the panel. The tool automatically detects all lists displayed on the current page. Each list appears with its name, subscriber count, and status alongside a checkbox. The target list is marked with a green "TARGET" label and its checkbox is disabled to prevent self-selection. Select the source lists you want to merge. Choose a target list from the dropdown. Toggle "Archive source lists" to keep them as archived lists instead of deleting them permanently. The preview section shows how many lists are selected and the target. Finally, click "Merge Lists." Two confirmation dialogs appear to prevent accidental merges. The tool processes each list with a 600ms delay, showing progress as each list is merged.

TECHNICAL OPERATION — Mailchimp API List Merging with Subscriber Transfer

This tool uses Mailchimp's API (version 3.0) to perform list merges reliably. It first extracts the user's API key and data center from the page (using regex to find `api_key` in scripts or meta tags), then constructs a POST request to `/lists/{sourceId}/merge?target_list_id={targetId}` for each source list. This endpoint moves all subscribers from the source list to the target list in a single operation. When the "Archive source lists" toggle is enabled, the tool sends a PATCH request to `/lists/{sourceId}` with a payload of `{ status: "archived" }`, preserving the list as archived. If disabled, the source lists are deleted permanently after the merge completes. The API approach is more reliable than DOM-based simulation because it works independently of Mailchimp's UI structure, supports proper error handling with HTTP status codes, and can handle large lists efficiently. A 600ms delay between merges prevents API rate limiting.

THE PANEL

The extension panel is fully draggable and remembers its position per site session. It snaps to the nearest edge of the browser viewport when dragged within 50 pixels of any side. You can collapse the panel to a compact title bar using the minimize button, preserving your selection state. The panel resizes vertically by dragging the bottom edge. Press the Escape key to close the panel instantly without losing your list selection. The preview updates in real-time as you select lists or change the target.

PLEASE NOTE

This tool requires the free BotGentz extension to function. The script uses Mailchimp's API and requires your session to be authenticated. It does not store, transmit, or log any list data, subscriber information, or user activity. All API requests are made locally from your browser session. The tool relies on extracting your API key from the page, which may expire if your session times out. Mailchimp may update its DOM structure over time, which could affect list detection; we monitor and release compatibility updates as needed. Merging lists moves all subscribers to the target and is permanent — source lists are deleted unless the "Archive source lists" toggle is enabled. Review the preview and confirmation dialogs carefully before confirming. Export formats include CSV and JSON for maximum compatibility with analysis tools.