Carrier Service Migration Crisis: How Teams Navigate Shopify's GraphQL Deadline While Managing E-commerce Platform Replatforming

By February 1, 2025, all public apps using deprecated product and variant REST API endpoints must migrate to GraphQL, with custom apps following by April 1, 2025. But here's the catch that makes this deadline particularly brutal: B2B e-commerce migration spending is projected to hit $36 trillion by 2026, as businesses simultaneously wrestle with platform replatforming projects alongside API changes.

The collision of these two migrations creates a perfect storm for carrier service integrations. Shopify's CarrierService resource provides real-time shipping rates to merchants, and using it requires adding carrier services to shops that provide applicable shipping rates at checkout. When teams attempt both API and platform migrations simultaneously, these critical integrations often become the first casualties.

Sound familiar? You're not alone if your team is juggling Shopify's GraphQL migration while planning a move to BigCommerce, Adobe Commerce, or a headless architecture.

Shopify CarrierService API Migration Crunch

The REST Admin API became legacy as of October 1, 2024, with all new public apps required to use GraphQL exclusively after April 1, 2025. For carrier integrations specifically, this impacts any service using the CarrierService resource to provide dynamic shipping rates.

The technical challenges run deeper than simple endpoint swaps. When Shopify requests shipping rates via callback URLs, response objects must contain specific JSON array formats with required fields for proper integration functionality. GraphQL introduces different data structures, authentication patterns, and error handling that can break existing webhook implementations.

Testing remains the biggest constraint. Some platforms like Cloudhooks moved their internal deadline to January 20, 2025—ahead of Shopify's February requirement—to allow buffer time for testing and validation. Most teams discover integration issues only during live checkout flows, where backup rate failures directly impact customer experience.

Here's what teams miss: Carrier services require Advanced Shopify plans or higher, Shopify plans with yearly billing, or a $20 monthly add-on fee. Platform changes can accidentally disable carrier service access, breaking integrations without obvious error messages.

Platform Migration Multiplies Integration Complexity

While Shopify GraphQL migration dominates headlines, 68% of B2B buyers shifted to online channels in 2024, with 61% of businesses migrating to SaaS-based e-commerce platforms. These concurrent migrations create cascading integration failures that extend far beyond individual API changes.

Common migration triggers include performance bottlenecks, cost optimization pressures, and capability gaps in existing platforms. B2B ecommerce replatforming has become a planning priority as buyers now use an average of 10 interaction channels, requiring consistent pricing, inventory, and experiences across every touchpoint.

Carrier integrations break during platform switches because each e-commerce system implements shipping APIs differently. BigCommerce uses different webhook structures than Shopify. WooCommerce requires distinct authentication methods. Adobe Commerce handles rate calculations through separate modules entirely.

The timing compounds complexity exponentially. Teams discover that their carefully planned Shopify-to-BigCommerce migration timeline now includes emergency GraphQL conversion work. Carrier rate providers like Cargoson, ShipStation, and EasyPost suddenly require dual integration maintenance during transition periods—something most project budgets never accounted for.

Integration Architecture That Survives Migrations

Smart teams build carrier integrations with an abstraction layer that isolates shipping logic from platform-specific APIs. Instead of directly calling Shopify's CarrierService endpoints, create middleware that translates platform requests into standardized formats.

Webhook reliability becomes critical during dual-platform operations. Configure separate webhook endpoints for each platform during transition periods, then implement request deduplication logic to prevent duplicate rate calculations. Monitor webhook delivery failures aggressively—most platforms retry failed webhooks differently, which can overwhelm carrier APIs during cutover windows.

Documentation proves essential for rollback scenarios. Maintain parallel configurations for both platforms with detailed environment variables, authentication credentials, and endpoint mappings. Teams using solutions like Cargoson report smoother transitions because unified APIs reduce the number of individual carrier integrations requiring migration.

Rate limiting strategies need adjustment during migrations. Running parallel integrations doubles API call volumes to carrier services. Real-time shipping rate calculations consider destination addresses, package weights, dimensions, and other details to generate precise quotes, but dual-platform scenarios can trigger rate limits that cause checkout failures.

Migration Execution Framework

Start with comprehensive carrier integration audits before beginning any migration. Document every active carrier service, webhook endpoint, authentication method, and dependency. Most teams discover forgotten integrations during this phase—legacy carrier services still processing a handful of monthly transactions but critical for specific customer segments.

Implement phased migration approaches with careful validation gates. If carrier APIs don't respond or generate errors, Shopify uses backup rates based on cart weight, and new service codes must be selected in shipping profiles every time changes are made. Test backup rate scenarios extensively because customers will encounter them during migration windows.

Manage authentication transitions carefully during platform switches. GraphQL requires different scoping than REST APIs. New platforms need separate API credentials entirely. Maintain both credential sets during transition periods, and implement monitoring that alerts on authentication failures across both systems.

Plan for extended dual-platform operation periods. 47% of companies face integration difficulties during migrations, with 39% struggling with legacy system compatibility and 33% reporting data migration challenges. Budget for longer overlap periods than initial estimates suggest.

Cost and Risk Management

Budget planning must account for dual-platform operation costs. Running parallel integrations typically doubles infrastructure expenses, API usage fees, and monitoring costs. Companies like Lull achieved 25% cost reductions post-migration through reduced infrastructure and payment processing fees, but transition periods require higher short-term spending.

SLA maintenance becomes challenging during migration windows. Establish clear expectations with customers about potential shipping calculation delays. Most carrier integrations experience 2-5 second response time degradation during dual-platform periods due to additional validation steps and fallback logic.

Team resource allocation needs careful planning. GraphQL requires different approaches than REST, with some operations needing restructuring and multiple steps to achieve equivalent results. Plan for learning curves that extend migration timelines beyond technical work estimates.

Communication strategies should prepare customers for service variations during cutover periods. Most successful migrations include advance notification about backup rate usage, potential checkout delays, and customer service contact information for shipping-related questions during transition windows.

Lessons from Early Migration Veterans

Teams that completed successful dual migrations consistently emphasize testing thoroughness over speed. Mock checkout scenarios using real product catalogs, actual customer addresses, and peak traffic volumes. Synthetic testing misses edge cases that appear only under production conditions.

Common failure patterns include webhook timeout cascades, authentication token refresh failures, and rate calculation discrepancies between platforms. Early adopters recommend maintaining detailed logs of all carrier API interactions during migration periods to diagnose issues quickly.

Timeline expectations consistently prove optimistic. Most teams initially estimate 2-3 month migration windows but require 4-6 months when accounting for GraphQL conversion work, testing phases, and inevitable integration debugging. Factor these realistic timelines into project planning from the beginning.

Long-term architectural decisions that pay dividends include investing in unified carrier integration platforms like Cargoson that handle multiple carrier APIs through single endpoints, implementing comprehensive monitoring from day one, and maintaining staging environments that accurately mirror production complexity.

The carrier service migration crisis isn't just about API changes—it's about building resilient integration architectures that survive the next inevitable platform evolution. Teams that invest in abstraction layers, comprehensive testing, and unified integration platforms emerge stronger from these challenging migration periods.