What are the best API-first companies?

This blog post has been written by the person who has mapped the API-first market in a clean and beautiful presentation

The API-first economy has matured into a $14 billion funding powerhouse with 74% of organizations now adopting API-first approaches.

Geographic concentration remains stark, with 65% of API startup funding flowing to US-based companies, while emerging hubs like Singapore show exceptional 44.9% growth rates. The sector demonstrates remarkable resilience during challenging market conditions, driven by increasing demand for AI-powered APIs and machine learning model access.

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Which API-first companies are considered the top performers globally in 2025?

Stripe dominates the API-first landscape with a $91.5 billion valuation, processing $1.4 trillion in transactions during 2024.

Kong achieved a significant milestone with a $175 million Series E funding round at a $2 billion valuation, led by Tiger Global and Balderton Capital. The company's API management platform now incorporates AI-infused capabilities and advanced security gateways. Twilio remains a pioneer in the communications API space, having established the API-as-a-product model that influences the entire industry.

Postman commands 60% market share in API development environments with $433 million in total funding. The company continues to strengthen its position as the go-to platform for API testing and documentation. Upvest raised €100 million in Series C funding and processes over 1 million trades weekly through their investment infrastructure APIs. Alpaca secured $52 million in Series C funding and enables 5 million+ investment accounts through brokerage APIs.

Emerging leaders include Stainless, which raised $25 million in Series A funding led by Jennifer Li at a16z, focusing on SDK generation and API tooling for top AI model providers including OpenAI, Anthropic, and Meta. KPay achieved a record-breaking $55 million Series A in Singapore, serving 45,000+ merchants across Asia with financial management APIs.

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Which API-first startups have attracted the most investment funding in 2024 and 2025 so far, and what amounts did they raise?

API-first companies collectively raised over $14 billion across 60+ major deals in 2024-2025, with the sector maintaining resilience during challenging market conditions.

Kong's $175 million Series E at a $2 billion valuation represents the largest single funding round among API-first companies in this period. Upvest secured €100 million in Series C funding, positioning itself as a leader in investment infrastructure APIs. KPay's $55 million Series A marked the largest Series A funding round for API companies in Southeast Asia.

The AI API market captured 18% of global venture capital funding in 2024, representing a 260% increase from the previous year. Stainless raised $25 million in Series A funding, while Alpaca secured $52 million in Series C funding. These funding rounds demonstrate investor confidence in API-first business models, particularly those serving developer communities and enabling AI integration.

Fintech APIs dominate investment with 35-40% of total funding, followed by healthcare APIs gaining momentum driven by regulatory mandates. AI/ML APIs captured significant attention with their 18% share of global venture capital funding, driven by increasing demand for AI-powered APIs and machine learning model access.

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Who are the most active or notable investors backing API-first companies, and what conditions or terms have they typically offered?

Accel leads API-first investments with 123 investments in API companies, including notable portfolio companies like Algolia and Monzo.

Andreessen Horowitz (a16z) made 122 investments in API companies and led Stainless' Series A round. Tiger Global demonstrated strong conviction by leading Kong's $175 million Series E round. Sequoia Capital remains active across various stages of API-first investments, while Index Ventures has made significant investments including Algolia.

Series A rounds typically range from $2-15 million for 15-30% equity, with valuations varying based on developer adoption metrics and proven business models. Later-stage rounds show premiums for companies with strong developer communities and validated revenue models. Geographic funding disparities persist, with US funding rounds typically 2-3 times larger than European equivalents for comparable companies.

Investment terms increasingly focus on developer adoption metrics, API call volumes, and revenue per developer as key performance indicators. Investors prioritize companies with strong developer experience, comprehensive documentation, and clear paths to monetization through API usage-based pricing models.

Which regions or countries are leading in API-first innovation and startup formation?

The United States maintains dominance with 76.7% of North American market share and $107 billion market value, benefiting from the strongest venture funding ecosystem.

Which API-first startups have received awards or other formal recognition for their innovation, growth, or impact?

API World 2025 Awards represent the definitive recognition in the API industry, with 20 categories celebrating innovation and adoption across the ecosystem.

SmartBear API Hub won the 2025 IoT Innovation Award for Enterprise Solution of the Year, marking five consecutive years of industry recognition. Bahwan CyberTek received the India Technology Excellence Award 2024 in the API-Banking category for their innovative Open API Solution. F5 was named a finalist for Best API Security in the 2025 SC Awards, highlighting continued innovation in API security.

Beyond formal awards, several API-first companies have gained recognition through strategic partnerships and market leadership positions. These recognitions often translate into increased investor interest and higher valuations, as industry awards serve as third-party validation of technical excellence and market adoption.

Recognition patterns show that security-focused API companies receive particular attention from industry awards, reflecting the growing importance of API security in enterprise adoption decisions.

Are there any API-first startups that have formed strategic partnerships or are backed by major tech giants or industry incumbents?

Major tech giants increasingly prefer strategic partnerships over acquisitions, allowing them to access cutting-edge API technology while providing startups with capital and infrastructure support.

Microsoft partnered with Inflection AI for $650 million, integrating conversational AI technologies into their ecosystem. Amazon made strategic agreements with Adept and Covariant for AI agent development, focusing on API-driven automation capabilities. Google continues partnerships with Character.ai and other AI-powered API providers to enhance their cloud offerings.

These partnerships demonstrate a shift toward strategic collaboration rather than outright acquisition, enabling tech giants to access innovative API technologies without full integration challenges. Startups benefit from enterprise distribution channels, technical infrastructure, and validation from established market leaders.

Strategic partnerships often include preferred integration status, co-marketing opportunities, and access to enterprise sales channels, providing API startups with accelerated market penetration and credibility among large enterprise customers.

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What technological breakthroughs or R&D achievements have API-first companies made so far in 2025?

AI-driven API development represents the most significant technological breakthrough, with more than 30% of API demand increase coming from AI and tools using large language models (LLMs) by 2026.

Security enhancements have become paramount, with zero-trust models and advanced authentication becoming standard across the industry. API security now takes priority over performance and scalability for 76% of CTOs, leading to innovations in real-time threat detection and behavioral analytics integration.

Serverless-first architecture has emerged as the dominant pattern, with 74% of companies now adopting API-first approaches and serverless architecture. The serverless computing market is projected to reach $44.7 billion by 2029, driven by API-first development patterns. AI-powered API management tools now provide predictive analytics and automated optimization capabilities.

Composition APIs are gaining prominence for flexible service integration, while GraphQL and Async APIs offer greater flexibility and real-time capabilities. Edge computing APIs support low-latency, decentralized architectures, enabling new use cases in IoT and mobile applications.

What promising R&D initiatives or breakthroughs are expected from API-first companies in 2026?

Gartner predicts that more than 80% of enterprises will use generative AI APIs or deploy GenAI-enabled applications in production by 2026.

API-first development will become essential for businesses operating in dynamic markets, with serverless-first development dominating API architecture patterns. Independent software vendors are expected to embed GenAI capabilities in 80% of their enterprise applications by 2026, driving massive demand for AI-powered APIs.

Emerging technologies include advanced composition APIs for flexible service integration, enhanced GraphQL implementations, and sophisticated Async APIs for real-time capabilities. Edge computing APIs will support ultra-low-latency applications, while quantum computing APIs may begin emerging for specialized computational tasks.

Security innovations will focus on automated threat response, advanced behavioral analytics, and zero-trust architectures specifically designed for API ecosystems. API governance and lifecycle management tools will incorporate AI-driven optimization and predictive maintenance capabilities.

Which API-first companies show other notable traits such as unique business models, rapid scaling, or strong community ecosystems?

Stripe pioneered the developer-first business model with comprehensive documentation, extensive language support, and transparent pricing that scales with transaction volume.

Postman built the largest API developer community with over 25 million users, creating network effects through shared collections, collaborative workspaces, and community-driven API discovery. Twilio established the API-as-a-product model, famously reducing complex telephony infrastructure to five simple API calls.

Kong demonstrates rapid enterprise scaling with its API management platform serving Fortune 500 companies while maintaining developer-friendly approaches. Stainless focuses on developer experience optimization, automatically generating SDKs and documentation for AI model providers.

Unique business model innovations include usage-based pricing aligned with customer success, freemium tiers that convert developers into enterprise advocates, and marketplace models connecting API providers with consumers. Strong community ecosystems typically feature comprehensive documentation, active developer forums, extensive integration libraries, and regular developer events.

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How much capital in total was invested or raised in the API-first sector globally during 2024 and so far in 2025?

API-first companies collectively raised over $14 billion across 60+ major deals during 2024-2025, demonstrating sector resilience during challenging market conditions.

The AI API market captured 18% of global venture capital funding in 2024, representing a 260% increase from the previous year. Fintech APIs dominated investment allocation with 35-40% of total funding, while healthcare APIs gained momentum driven by regulatory mandates and digital transformation initiatives.

Geographic distribution shows 65% of funding flowing to US-based companies, 20% to European companies, and 15% to Asia-Pacific companies. Despite the geographic concentration, emerging markets like Singapore demonstrate exceptional growth rates of 44.9%, indicating shifting investment patterns.

Investment concentration remains significant, with companies that raised more than $50 million representing the majority of total sector funding. This concentration reflects investor preference for proven business models and established developer adoption metrics.

What investment trends and fundraising volumes should we expect for API-first companies in 2026?

The total API economy is projected to reach $300 billion by 2026, with the API management market expected to grow at 25% CAGR to $32.77 billion by 2032.

AI-powered API platforms will continue attracting premium valuations, driven by 30% increase in API demand from AI and LLM tools by 2026. Vertical-specific API solutions in fintech, healthcare, and e-commerce will command higher multiples due to regulatory compliance requirements and specialized domain expertise.

Geographic investment patterns will likely shift toward Asia-Pacific markets, with Singapore leading regional expansion initiatives. European companies with strong technical teams and lower valuations may attract increased US investor attention for geographic arbitrage opportunities.

Consolidation trends suggest well-capitalized companies will command premium valuations, while struggling companies face difficulty raising follow-on funding. Enhanced security and governance capabilities will become critical differentiators for investment decisions. The serverless computing market projected to reach $44.7 billion by 2029 will drive infrastructure-related API investments.

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Who are the standout founders or teams behind the most successful API-first companies and what distinguishes them?

Jeff Lawson of Twilio pioneered the API-as-a-product model, famously stating "We have taken the entire messy and complex world of telephony and reduced it to five API calls."

Alex Rattray, founder of Stainless, brings deep API expertise as a former Stripe executive who led API documentation and SDK tooling initiatives. His background informed Stainless' approach to solving developer experience challenges in API integration. Jacques Declas, co-founder and CEO of 42Crunch, combines over 20 years of enterprise software experience with specialized API security expertise from roles at Forum Systems, Vordel, and Intel.

Successful API-first founders typically demonstrate deep technical expertise in API development and integration, combined with strong developer empathy and understanding of B2D (business-to-developer) sales dynamics. They possess the ability to scale technical teams while maintaining product quality and have experience with platform-based business models.

Common backgrounds include former engineering roles at major tech companies like Google, Stripe, and Microsoft, enterprise software and integration experience, previous startup experience in developer tools or infrastructure, and strong technical communication skills. These founders understand that API success depends on developer adoption, comprehensive documentation, and seamless integration experiences.

Conclusion

Sources

1. API Economy Funding Analysis
2. Renew Capital - Startup Leadership
3. API Economy Market Size
4. Dev.to - API Design First Companies
5. API Economy Investors
6. Stainless Series A Announcement
7. TeaserClub - API Investors
8. SeedTable - API Product Investors
9. Cognitive Market Research - API Market
10. API World Awards
11. SmartBear IoT Award
12. Bahwan CyberTek Award
13. F5 API Security Award
14. Tech Giants Strategic Partnerships
15. Gartner API Demand Predictions
16. API7 - API Management Trends
17. LinkedIn - CTO Investment Trends
18. AnyAPI - Serverless Development Trends
19. API Ninjas - 2025 Trends
20. 42Crunch Leadership
21. TechJury - API Market Size