Migrate from Aweber to Mailchimp

Audit AWeber account structure and export schema

FlitStack connects to your AWeber account via OAuth and inventories all lists, custom field definitions, tags, campaigns, and autoresponder configurations. We generate a pre-migration audit report listing record counts per list, custom field types, active automation count, and any subscribers with incomplete profile data. This report establishes the baseline for migration scope and timeline. If your AWeber account uses multiple lists with shared subscribers, we flag duplicates before creating the Mailchimp audience mapping plan.

Create Mailchimp audiences and configure merge field schema

Before subscriber data moves, FlitStack provisions Mailchimp audiences matching your AWeber list structure. For each audience, we create merge fields corresponding to AWeber custom fields — applying the correct Mailchimp type (text, number, date, dropdown, etc.) based on pre-migration validation. We also configure audience-level settings (from name, reply-to, permission reminder) from AWeber's list settings. If any merge field types require adjustment based on actual data values, we document those changes for your Mailchimp admin to approve before proceeding.

Extract subscribers via AWeber API with rate-limit management

Subscriber extraction runs against AWeber's REST API using paginated requests (max 100 subscribers per page). FlitStack implements a request queue with 500ms minimum spacing to stay within AWeber's 120 req/min ceiling. For accounts with active integrations, extraction runs during off-peak hours to minimize interference. Tags, custom field values, and activity history (opens, clicks) are retrieved in parallel requests per subscriber. All extraction runs generate an audit log with timestamps for every API call and response status.

Transform and load subscriber data into Mailchimp audiences

Subscriber records load into Mailchimp via the Marketing API's batch upsert endpoint (up to 500 records per batch). Status values, tag assignments, and merge field data map according to the field mapping table established in Step 2. AWeber's 'complained' status routes to Mailchimp archived with a Source_Status__c custom field flag. Duplicate detection matches subscribers by email address across audiences. After loading, FlitStack generates a reconciliation report comparing subscriber counts, status distribution, and custom field fill rates between AWeber source and Mailchimp destination.

Export automation logic and deliver rebuild reference

For each AWeber autoresponder sequence, FlitStack generates a structured CSV containing: trigger event, trigger delay, message subject, message content preview, and conditional branch logic. This document serves as a blueprint for rebuilding each sequence in Mailchimp's Customer Journey builder. We deliver the CSV alongside a written summary of each journey's business logic so your Mailchimp admin can recreate the automation without reverse-engineering from AWeber's campaign data. Landing page and sign-up form configurations are documented separately for manual rebuild.

Run delta pickup and validate final reconciliation

After the primary migration run, a delta-pickup window (typically 24–48 hours) captures any new subscribers, unsubscribes, or profile updates that occurred in AWeber during the cutover period. FlitStack applies these changes to Mailchimp via the same API-driven process. A final reconciliation report compares AWeber's live subscriber count and status distribution against Mailchimp's imported totals. If discrepancies exceed the agreed tolerance threshold (default: 0.1% of total records), FlitStack runs a targeted re-sync for affected segments. One-click rollback to the pre-migration state remains available for 72 hours after go-live.