Evaluate SLA performance, transit time matrices, and true landed-cost models. Confirm WMS/API integrations for storefronts and carriers, inspect facility throughput (dock doors, conveyors), and request sample pick/pack pricing. Consider network density and local carrier contracts to optimize regional delivery lanes. You can also compare cost-per-order across volume bands to predict scaling impacts.

Prioritize secure pallet racking, ample dock doors, flexible staging for full-truck and LTL loads, and cross-dock capabilities. Verify yard capacity for trailers, inbound staging workflows, barcode scanning, ASN handling, and certified inventory controls to meet B2B compliance and EDI requirements.

Labor availability, local wage rates, and seasonal demand influence pick/pack throughput and overtime exposure. Expect 3PLs to price peak-season labor into holiday rates or surge fees. Ask providers about temporary staffing partnerships, productivity targets, and historical uptime during peak windows to gauge risk.

3PLs should provide multi-carrier parcel contracts, LTL and FTL options, and regional courier integrations for last‑mile coverage. Look for direct connections to national LTL networks and negotiated parcel rates, plus visibility into carrier APIs and automated label generation to streamline routing and returns.