Ismael N. (Numi) Castillo

About Me

Fractional CTO | Technology Strategy and Transformation Leader

I partner with founders, chief executives, and boards who recognize that technology decisions carry the same weight as capital allocation. Across my career, I've worked with startups, mid-size companies, guided regulated banks, global energy companies, and high-growth SaaS firms through inflection points where platform resilience, security architecture, and market velocity determined their survival. From architecting multi-year ERP transformations with The Hackett Group to modernizing cloud and DevSecOps technology workforce for Fortune 100 clients at SkillStorm, I transform strategic vision into scalable architectures and enduring governance frameworks.

As Chief Technology Officer at Credit One Bank, I implemented zero-trust security models and reengineered service delivery, achieving over $16M in annual cost reductions. At Citi, I led the adoption of hybrid cloud across Latin America and Mexico, optimizing technology operations that delivered millions in savings while enabling market expansion. My technical foundation was established at IBM, where I earned benchmark leadership for pSeries solutions, received four U.S. patents, and drove strategic alliance growth exceeding $1 million year-over-year in contract value.

These experiences shaped a leadership approach that bridges board-level strategy with engineering execution, ensuring every architectural decision advances enterprise value.

Core capabilities

Strategic Technology Leadership – I own P&L responsibility for technology investments, balancing growth ambitions with operational realities and regulatory requirements.

Enterprise Architecture as Business Strategy – Cloud, infrastructure, and application decisions are architected around compliance frameworks, cost optimization, and revenue enablement, not technical elegance alone.

Scalable Governance Models – My leadership framework emphasizes people development, process optimization, and knowledge transfer that sustains transformation beyond engagement timelines.

Executive Team Development – I build technology leadership capacity within organizations, fostering cross-functional collaboration and embedding practices that compound over time.

Personal Background

Born in the Dominican Republic, I bring bilingual fluency (English/Spanish) and a cross-cultural perspective to global technology initiatives. Based in Orlando with my wife, I actively mentor emerging technology leaders and engage with our diverse professional community.

Select Work Experience

  • Technology and Transformation Strategic Advisor

    As Technology and Transformation Strategy Advisor, I guide comprehensive digital transformation strategies directly with C-suite leaders for Meet Business Group. My responsibilities encompass creating robust governance frameworks for significant technology investments, assessing and developing training programs for technology executives, and critically evaluating emerging technologies such as AI, cloud computing, and advanced data analytics to inform strategic direction.

  • Sr. Director, Technology Strategy and Transformation Consultant

    As Senior Director, I led a strategic enterprise-wide technology transformation program (ERP) for a large global manufacturing client, serving as Head of Business Transformation and Enablement program manager. My core focus was on driving business enablement and operational scalability through their ERP implementation. In this role, I directed the strategic design and execution of a comprehensive enterprise-wide technology implementation roadmap, encompassing readiness assessments and a robust business and stakeholder alignment strategy

    Key Highlights:

    • Facilitated executive and Voice of Customer (VoC) workshops to define strategic technology KPIs and establish a robust performance measurement framework, ensuring long-term adoption and optimization directly linked to measurable business value.

    • Designed comprehensive program governance and risk management models to strategically guide phased rollout and manage complexity across this large-scale digital transformation.

    • Delivered an integrated technology deployment strategy, aligning diverse cross-functional stakeholders from IT, operations, and finance.

  • SVP, Client Partner

    In this role, I led multi-vertical technology consulting engagements, serving as a strategic advisor and program lead for enterprise clients, particularly within the energy, financial, and healthcare sectors. I drove the execution of high-visibility technology workforce strategy initiatives, strategically aligning cross-functional engineering, compliance, and business teams to achieve critical platform modernization, DevSecOps adoption, and risk reduction goals. I also oversaw a team of 60+ engineers, managing the full lifecycle of complex technical engagements from solution design to delivery.

    Achievements:

    • Built and scaled a thriving Cloud, DevSecOps, and SRE engagement practice specifically for the Financial and Energy sector verticals.

    • Secured and cultivated pivotal business relationships within the oil and gas sectors, directly driving a substantial 23% business growth.

    • Achieved a 28% increase in revenue (2023) within the financial industry through strategic program leadership

  • Manager of Strategic Alliance Partners

    As Senior Business Development Manager, I drove exceptional revenue growth and market expansion through strategic technology alliance partnerships and innovative go-to-market (GTM) strategies. I collaborated with product and engineering teams to guide technology roadmap alignment across joint initiatives, delivering scalable GTM frameworks for security and data compliance products. I also established robust program governance standards to manage execution across complex technology alliance workstreams.

    Key Contributions:

    • Secured multi-million dollars in total contract value (TCV) with strategic partners, directly leading to significant new customer acquisition and expansion of existing accounts.

    • Expanded market reach and competitiveness by fostering strategic alliances with leading hardware (e.g., NetApp, Nutanix) and security vendors (e.g., Palo Alto, CrowdStrike).

    • Cultivated and optimized integrated channel marketing (ICM) partnerships to generate substantial new revenue opportunities and accelerate top-of-funnel activities.

    • Maximized partnership performance and provided actionable market intelligence through the development and utilization of Salesforce and Tableau dashboards.

    • Empowered security alliance partners with a tailored GTM playbook, ensuring product integration and market relevance, ultimately exceeding MBO quotas quarter by quarter.

  • Chief Technology Officer

    As SVP, Chief Technology Officer, I directed and served as executive sponsor for large-scale enterprise-wide IT transformation programs, driving strategic initiatives across infrastructure modernization, DevSecOps adoption, ITSM, and cutting-edge Zero Trust security architectures. I also spearheaded the cultural adoption of DevOps principles and designed a comprehensive Zero Trust architecture, which significantly reduced vulnerabilities and ensured stringent regulatory compliance.

    Impact at a Glance

    • 70 % fewer Sev-1 incidents after rolling out automated CI/CD pipelines and shift-left quality gates.

    • Zero Trust security blueprint implemented bank-wide, meeting stringent regulatory requirements and closing critical vulnerability gaps.

    • Remote-first workforce enablement through a modern EUC strategy and desktop virtualization, boosting productivity during the pandemic.

    • Next-generation data center architected for 24×7 resilience across 100+ core banking systems.

    • ServiceNow-driven ITSM replaced the legacy NOC, elevating service transparency and customer experience with new Production Management directive.

    • $13 M+ annual run-rate savings (10 % YoY) achieved via infrastructure consolidation and vendor rationalization.

    This integrated transformation positioned Credit One Bank for scalable digital growth while materially reducing operational risk and cost.

  • Senior Vice President, Technology Platform Architecture & Service Delivery – Global Consumer Bank
    As Citi’s senior technology leader for Latin America and Mexico, I orchestrated mission-critical service delivery, enterprise platform architecture, and large-scale transformation programs that underpinned retail-banking growth. Partnering with global MD-level executives, I drove hybrid-cloud adoption, modernized distributed platforms supporting more than 2,000 consumer-banking applications, and embedded resilient service-management practices that elevated availability and customer experience across the region.

    Signature Achievements

    • Stabilized production at scale. Cut critical-incident volume by 90 % from 2015 onward by instituting rigorous fault-domain analysis, production-readiness reviews, and 24×7 service-health dashboards.

    • Unlocked recurring savings. Led cross-domain cost-efficiency initiatives that delivered $14 M+ in annual run-rate savings, funding further digital-banking innovation.

    • Accelerated time-to-market. Standardized platform patterns and automation frameworks that improved release velocity for new features by 60 %, enabling faster response to evolving regulatory and customer demands.

    • Advanced Citi’s Hybrid-Cloud Strategy. Architected scalable, cost-effective landing zones and governance models that became reference designs for global consumer-banking workloads.

  • Senior Technical Consultant & Alliance Leader

    During a decade of progressive leadership at IBM, I advanced from engineering roles within Lotus Software to driving performance engineering for the Power Systems cloud stack and managing global software-vendor alliances. Partnering with cross-functional product, development, and sales teams, I optimized virtualization platforms, created go-to-market frameworks for strategic partnerships, and championed open-source and hybrid-cloud adoption across the portfolio. This blend of deep technical insight and market-facing execution consistently improved product competitiveness and unlocked new revenue streams for IBM’s hardware, software, and services divisions.

    Signature Achievements

    • Optimized PowerVM for cloud scale. Led performance analysis and capacity-planning programs that boosted virtualization throughput by up to 30 percent and deferred millions in capital spend for flagship customers.

    • Accelerated release velocity. Built an automated test harness and competitive-benchmark framework that cut time-to-market for the Power Systems cloud stack by 25 percent while maintaining enterprise-grade quality.

    • Generated joint pipeline through the Oracle–IBM Alliance. Negotiated co-selling playbooks, technical-integration roadmaps, and field-enablement assets that increased solution attach rates across databases, middleware, and infrastructure offerings.

    • Increased ISVs onboarding to the IBM Power Systems Marketplace. Designed self-service reference architectures, readiness workshops, and enablement collateral that reduced partner activation from months to weeks.

    • Advanced IBM’s open-source leadership. Championed early adoption of OpenStack on Power and x86 platforms, producing benchmark data that informed R&D investment and positioned IBM as a credible hybrid-cloud partner.

    • Innovation. Filed four U.S. patents related to AIX, user experience and other non-technical topics reinforcing IBM’s culture of innovation and technical thought leadership.

  • Consultant, Dominican Republic Customs Modernization Program

    Contracted by UNDP to modernize the Dominican Republic’s customs-clearance ecosystem, I served as the principal technology adviser to senior government stakeholders, translating DR’s Customs Organization processes, tariffs, and import/export laws into a phased digital-transformation roadmap. My remit encompassed current-state assessment, requirements engineering, vendor evaluation, and change management planning for a country-wide single-window platform that would ultimately enhance trade transparency and revenue collection.

    Signature Achievements

    • Mapped and re-engineered 40+ import/export workflows to align with revised Dominican Republic Customs guidelines, eliminating redundant manual checkpoints and paving the way for full process automation.

    • Drafted functional and technical specifications for an electronic cargo-tracking and risk-management system, providing a blueprint that development partners used to fast-track prototyping and funding approval.

    • Facilitated inter-agency consensus (Customs, Agriculture, Health, Ports Authority) through a series of bilingual design-thinking workshops that clarified ownership, data-sharing protocols, and service-level expectations.

    • Authored the implementation governance model and KPI framework, equipping the Directorate General of Customs with measurable targets for clearance time, compliance rates, and revenue uplift post-launch.

Let’s discuss your toughest Business and Technology challenges—schedule a confidential consult now