Frontend
Using https://reactflow.dev/ to create the editor page.
Backend

Database

Database
- Their DB uses
TypeORM.
- Workflow Table schema - https://github.com/n8n-io/n8n/blob/3908f740ffcecd70d7899a566860a5626303c8d4/packages/%40n8n/db/src/entities/workflow-entity.ts
- Users table - https://github.com/n8n-io/n8n/blob/3908f740ffcecd70d7899a566860a5626303c8d4/packages/%40n8n/db/src/entities/user.ts
- Credentials table - https://github.com/n8n-io/n8n/blob/3908f740ffcecd70d7899a566860a5626303c8d4/packages/%40n8n/db/src/entities/credentials-entity.ts
Routes
- Webhook handler - https://github.com/n8n-io/n8n/blob/3908f740ffcecd70d7899a566860a5626303c8d4/packages/cli/src/webhooks/webhook-request-handler.ts
- Webhook handler 2 - https://github.com/n8n-io/n8n/blob/3908f740ffcecd70d7899a566860a5626303c8d4/packages/cli/src/webhooks/webhook-request-handler.ts