Fractional CTO for Series B
Series B companies are proven market leaders focused on dominating their category and expanding into adjacent markets. With significant capital and market validation, the technical challenge shifts fr...
Typical Funding
$15M - $50M
Team Size
50-150 people
Revenue
$10M - $30M ARR
Runway
36-48 months
Understanding Series B
Series B companies are proven market leaders focused on dominating their category and expanding into adjacent markets. With significant capital and market validation, the technical challenge shifts from proving product-market fit to building a multi-product platform that can support diverse customer needs across geographies. Engineering organizations are scaling from 30-50 to 100+ engineers, requiring sophisticated management structures, platform capabilities, and operational excellence. This stage is about building sustainable competitive advantages through technology while maintaining the innovation velocity that got you here.
Key Priorities at This Stage
- Scale engineering to 100+ people with multiple layers of management
- Build platform architecture supporting multiple products and verticals
- Expand globally: multi-region infrastructure, internationalization, data residency
- Establish engineering excellence: architecture review, technical strategy, innovation
- Build specialized functions: ML/AI, data science, security, platform engineering
- Implement advanced engineering practices: A/B testing, feature flags, experimentation
- Create developer platform enabling internal teams to ship independently
- Optimize infrastructure costs while scaling (FinOps discipline)
- Build strategic partnerships and integration ecosystem
- Prepare for Series C or potential IPO technical requirements
Why You Need a Fractional CTO
- Strategic guidance from CTOs who've scaled companies to IPO and beyond
- Proven platform architecture patterns from category-leading companies
- Network of executive engineering talent (VPs, Directors, Distinguished Engineers)
- Objective assessment of engineering org and leadership team effectiveness
- Board-level technical advisor with credibility among growth investors
Common Challenges at Series B
Coordination overhead with 100+ engineers slowing down product development
Platform can't support diverse product needs across customer segments
Technical strategy disconnected from business strategy and market opportunities
Senior engineering talent leaving for more innovative or higher-paying companies
Infrastructure costs growing faster than revenue (cloud spend optimization needed)
Global expansion requiring multi-region infrastructure and data localization
Legacy technical debt from earlier stages limiting innovation speed
Need for specialized technical capabilities (ML, security, platform) beyond core product
Engineering culture dilution as organization scales and becomes more corporate
Competition for engineering talent intensifying with multiple unicorns hiring
Budget Guidance for Series B
Fractional C T O
$10,000-$15,000/month (strategic advisor role, board observer, coaching CTO/VPs)
Engineering
$10M-$25M/year (80-150 engineers, 8-15 managers, 3-5 directors, 1-2 VPs)
Infrastructure
$30,000-$100,000/month (multi-region cloud, data platform, ML infrastructure)
Tooling
$10,000-$25,000/month (enterprise dev tools, security, compliance, analytics)
Recruiting
$500K-$1.5M/year (recruiting team, employer brand, university programs)
Training
$200K-$500K/year (leadership development, technical conferences, certifications)
R&d
$500K-$2M/year (innovation projects, technical explorations, prototypes)
Total Monthly Tech Burn
$1.1M-$2.5M/month
Success Story
Series B enterprise platform, 120 people, $45M raised, $18M ARR, expanding to multiple product lines and international markets
Challenge
CTO (promoted from VP Eng) struggling with strategic challenges while managing day-to-day. Engineering org of 65 can't support 3 different product lines efficiently. Each team building redundant capabilities. Infrastructure costs at $85K/month growing faster than revenue. Enterprise customers in EU requiring data residency. Board pushing for $50M ARR in 18 months requiring 2x engineering productivity.
Solution
Fractional CTO engaged as strategic advisor to CTO and board technical observer. Key initiatives over 24 months: 1) Defined platform strategy extracting common capabilities (auth, billing, notifications, integrations), 2) Created platform engineering team building internal developer platform, 3) Restructured org into product divisions with shared platform services, 4) Led FinOps initiative reducing infrastructure costs 40% while improving performance, 5) Designed multi-region architecture for EU/US data residency, 6) Coached CTO on strategic thinking and executive presence, 7) Recruited 3 senior directors to build leadership bench, 8) Established architecture review board and technical strategy process, 9) Built ML platform supporting AI features across products.
Result
Scaled from $18M to $62M ARR in 24 months with engineering org of 135 (vs. planned 180 - higher productivity). Platform reduced time-to-market for new products from 9 months to 6 weeks. Infrastructure costs decreased from $85K to $72K/month despite 3.5x growth (improved unit economics). Successfully launched in EU with compliant data residency. Three product lines on shared platform with consistent capabilities. CTO promoted to Chief Product & Technology Officer. Engineering NPS improved from 6.8 to 8.4. Raised $80M Series C at $850M valuation with strong technical diligence.
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