Customer Onboarding (FIX) Change Consultant6-Month Contract | Up to £500/day | Inside IR35 Hybrid London (2-3 days per week)OverviewOur client, a leading electronic trading business is delivering a number of complex change programmes impacting customer connectivity, onboarding and infrastructure. These initiatives involve transitioning institutional connectivity from Legacy to new within a live, regulated trading ecosystem.This role sits within the Customer Onboarding (FIX), supporting a highly experienced and knowledgeable team that is managing an increased workload as a result of the change programme of work. Additional delivery capacity is required to ensure customer migrations and onboarding activity continue to be executed in a controlled and structured manner.This is a hands-on, delivery-focused position supporting structured customer migrations, certification activity and onboarding change, ensuring controlled transitions with minimal disruption.The role combines technical FIX knowledge with strong stakeholder management, structured problem-solving and significant documentation ownership.Role Responsibilities Lead Customer Onboarding (FIX) session setup for migrating and new connectionsManage end-to-end connectivity testing, certification and validationExecute structured migration and onboarding workpacksCoordinate controlled customer cutovers and transition planningIdentify and resolve onboarding or connectivity issues proactivelyDraft, update and maintain onboarding