Sendcloud

Sendcloud's API is well-designed for shipping automation, following RESTful principles with comprehensive documentation.

API key authentication is simple, with good rate limiting (15 requests/second) and error handling. The API covers multi-carrier shipping, label generation, tracking, and returns management extensively.

Webhooks enable real-time updates, and bulk operations are well-supported. However, it requires a Sendcloud subscription and understanding of shipping workflows. It's excellent for e-commerce businesses needing shipping automation, particularly strong in European markets with 160+ carrier integrations.