Best API platform investors and their 2025 portfolio deals

APIs don't get media hype like consumer apps. But every software company runs on them. And VCs know it.

The API infrastructure market hit $9.8 billion in total funding as of 2025, with companies like Stripe hitting $91.5 billion valuations and Postman reaching unicorn status at $5.6 billion. These aren't just tools for developers anymore - they're the backbone of how modern software connects.

If you're building API infrastructure, integration platforms, or developer tools, you need to know which investors actually write checks for this space. Most won't fund infrastructure until you hit specific revenue milestones. Some only care about API management. Others want the full stack.

Quick list

Picking the right API investor

Experience: Find investors who've backed companies through scaling infrastructure at high request volumes. Most VCs don't understand the difference between 1,000 API calls and 1 billion. Ask their portfolio companies about actual help during scaling challenges like rate limiting, latency spikes, or managing breaking changes across versions.

Network: Check if they can intro you to potential integration partners and enterprise customers who need API solutions. That matters more than brand names. API companies grow through distribution partnerships, not consumer marketing.

Alignment: Make sure they've funded similar business models before. Developer tool investors often don't understand enterprise sales cycles. Enterprise investors won't get usage-based pricing models. Seed investors focused on B2C won't understand API-first go-to-market. Use PPT protection when sharing sensitive data.

Track record: Look at whether their portfolio companies raised follow-on rounds. Dead portfolio companies are a red flag. Check acquisition outcomes too - did APIs get shut down post-acquisition or integrated well? Track investor focus via deck activity.

Communication: Use Ellty to share your deck with trackable links. You'll see who actually opens your financial projections and which investors skip your API architecture slides.

Value-add: Generic "we have a great network" answers are useless. Ask what specific help they provided when their portfolio hit 10M daily requests or needed to migrate to a new architecture. Most can't answer.

How to approach API investors

Identify potential investors: Research recent deals on Pitchbook or Crunchbase filtering for API, developer tools, and infrastructure keywords. Seed funds won't lead your Series B, no matter how good your deck is. Check if they've invested in competing API categories - some VCs avoid conflicts, others want multiple bets.

Craft a compelling pitch: Show API request growth rates and revenue per API call in your pitch. Most investors are tired of "we're like Stripe but for X" without actual usage metrics. Lead with retention rates - API companies with 120%+ net retention get meetings fast.

Share your pitch deck: Upload to Ellty and send trackable links. Monitor which pages investors spend time on - if they skip your unit economics, that's useful information. When they spend 5+ minutes on your API architecture slides, you know they get it.

Utilize your network: Message portfolio founders on LinkedIn and ask about response times and actual value-add. Most will be honest. Don't ask for intros until you've done your homework on the investor's thesis.

Attend networking events: TechCrunch Disrupt and API World are where deals actually happen. Skip the small local events. Y Combinator Demo Days if you're in the batch. Most meaningful conversations happen in hallways, not during panels.

Engage on online platforms: Connect with partners on LinkedIn after you've been introduced. Cold DMs rarely work. Comment thoughtfully on their posts about API trends - but only if you actually have something to add. Avoid common GDPR mistakes when sending materials.

Organize due diligence: Set up an Ellty data room with your financial model, cap table, and API documentation before they ask. It speeds up the process. Include actual API specs, not just business docs.

Set up introductory meetings: Lead with your API call growth and gross margins. Don't waste 20 minutes on market size slides they've seen 100 times. Get to unit economics by slide 3. Show them actual API request patterns, not hypothetical TAM.

Why API infrastructure matters now

The API economy is growing faster than most realize. Hyperscalers spent roughly $350 billion in 2025 on AI-driven data centers and infrastructure. Every dollar spent on infrastructure needs API management, integration, and tooling.

API-first companies are pulling in record funding. Kong raised $175M at Series E in November 2024. Postman doubled its valuation from $2B to $5.6B in one year. These aren't outliers - they're signals that infrastructure investors finally understand APIs aren't just nice-to-have middleware.

The shift to AI agents accelerates API demand. As companies build AI-native applications, every model needs API access to external data and services. Postman's 2025 State of API report shows 93% of developers still use REST, but webhooks (50%), WebSockets (35%), and GraphQL (33%) are growing fast for real-time AI use cases.

18 best API infrastructure investors

1. Insight Partners

Insight Partners leads growth-stage infrastructure investments and has the track record to prove it. They led Postman's $225M Series D and understand how API platforms scale to billions of requests.

• Recent Deals: Postman $225M Series D (Aug 2021), Multiple cybersecurity and infrastructure rounds in 2024-2025
• LinkedIn: Insight Partners
• Sector Focus: SaaS, developer tools, API platforms, enterprise software, cybersecurity
• Stage Focus: Series C, Series D, growth equity
• Location: New York City, United States
• Website: insightpartners.com

2. Sequoia Capital

Sequoia doesn't miss on infrastructure. They backed Stripe from seed through to its current $91.5B valuation, understanding API platforms better than most.

• Recent Deals: Stripe multiple rounds through 2025 ($91.5B valuation Feb 2025), Semgrep $100M Series D, Numerous AI and infrastructure deals
• LinkedIn: Sequoia Capital
• Sector Focus: Infrastructure, developer tools, fintech, enterprise software, AI
• Stage Focus: Seed, Series A, Series B, growth
• Location: Menlo Park, United States
• Website: sequoiacap.com

3. Andreessen Horowitz (a16z)

a16z gets developer-first companies. They led RapidAPI's early rounds and participate in infrastructure deals that others miss.

• Recent Deals: RapidAPI $3.5M seed (2016) and $60M Series C (2021), Multiple crypto infrastructure investments, AI security startups
• LinkedIn: Andreessen Horowitz
• Sector Focus: Infrastructure, developer platforms, crypto, AI, enterprise SaaS
• Stage Focus: Seed, Series A, Series B, Series C
• Location: Menlo Park, United States
• Website: a16z.com

4. Index Ventures

Index backs API infrastructure at scale. Their investment in Kong's $175M Series E shows they understand gateway technology and API management.

• Recent Deals: Kong $175M Series E (Nov 2024), Wonderful $100M Series A (Nov 2025), Multiple infrastructure deals
• LinkedIn: Index Ventures
• Sector Focus: Infrastructure, API management, developer tools, enterprise software
• Stage Focus: Series B, Series C, Series D, Series E
• Location: London, United Kingdom / San Francisco, United States
• Website: indexventures.com

5. Bessemer Venture Partners

Bessemer has one of the largest cloud portfolios in VC. They backed Twilio through IPO and understand how developer platforms scale.

• Recent Deals: StayTerra funding (Jul 2025), Doppel $70M Series C (Nov 2025), Extensive cloud infrastructure portfolio
• LinkedIn: Bessemer Venture Partners
• Sector Focus: Cloud infrastructure, developer platforms, API tools, enterprise SaaS
• Stage Focus: Series A, Series B, Series C, growth
• Location: Redwood City, United States
• Website: bvp.com

6. Tiger Global Management

Tiger Global writes big checks fast. They participated in Stripe rounds and back API platforms that show strong unit economics.

• Recent Deals: Stripe multiple rounds, Celestial AI $250M Series C1, Urban Company pre-IPO rounds
• LinkedIn: Tiger Global Management
• Sector Focus: Infrastructure, fintech, enterprise software, API platforms
• Stage Focus: Series B, Series C, Series D, late-stage
• Location: New York City, United States
• Website: tigerglobal.com

7. Accel

Accel invested in Stripe's seed round and stayed through the growth stages. They get in early on infrastructure that matters.

• Recent Deals: Stripe seed round (2011), Vercel $9.3B valuation Series F (Sep 2025), PermitFlow $54M Series B (Dec 2025)
• LinkedIn: Accel
• Sector Focus: Infrastructure, developer tools, enterprise software, API platforms
• Stage Focus: Seed, Series A, Series B, Series C
• Location: Palo Alto, United States
• Website: accel.com

8. CRV

CRV backed Postman early at Series B and continued through Series D. They understand API collaboration platforms and developer workflows.

• Recent Deals: Postman Series B (Jun 2019) through Series D (Aug 2021), Developer tools portfolio
• LinkedIn: CRV
• Sector Focus: Developer tools, API platforms, infrastructure, enterprise software
• Stage Focus: Series A, Series B, Series C
• Location: Palo Alto, United States
• Website: crv.com

9. Notable Capital (formerly GGV Capital)

Notable Capital created the API-First Index tracking 150+ API companies. They understand the space deeply and back winners like Agora and Stream.

• Recent Deals: API-First Index portfolio tracking (51 companies including Stripe, Alchemy), LocalStack $25M Series A (Nov 2024)
• LinkedIn: Notable Capital
• Sector Focus: API-first companies, developer platforms, infrastructure, enterprise applications
• Stage Focus: Seed, Series A, Series B, Series C
• Location: Menlo Park, United States / Singapore
• Website: notablecapital.com

10. Lightspeed Venture Partners

Lightspeed has co-invested in multiple API infrastructure rounds. They led Anthropic's $3.5B Series E and understand infrastructure at scale.

• Recent Deals: Anthropic $3.5B Series E (2025), Multiple API and infrastructure co-investments, MuleSoft early rounds
• LinkedIn: Lightspeed Venture Partners
• Sector Focus: Infrastructure, API platforms, enterprise software, AI
• Stage Focus: Series A, Series B, Series C, growth
• Location: Menlo Park, United States
• Website: lsvp.com

11. Bond Capital

Bond joined Postman's Series D and focuses on infrastructure companies with proven unit economics. They move fast on deals they like.

• Recent Deals: Postman $225M Series D (Aug 2021), Infrastructure and developer tools portfolio
• LinkedIn: Bond Capital
• Sector Focus: Infrastructure, developer platforms, enterprise software
• Stage Focus: Series C, Series D, late-stage
• Location: San Francisco, United States
• Website: bond.com

12. Battery Ventures

Battery Ventures backs API infrastructure and developer tools. They joined Postman's Series D and have a strong enterprise software track record.

• Recent Deals: Postman Series D (Aug 2021), Enterprise infrastructure portfolio
• LinkedIn: Battery Ventures
• Sector Focus: Infrastructure, API platforms, enterprise software, developer tools
• Stage Focus: Series B, Series C, Series D, growth
• Location: Boston, United States
• Website: battery.com

13. Coatue

Coatue participated in Postman's $225M round and backs infrastructure at scale. They write large checks for proven platforms.

• Recent Deals: Postman Series D (Aug 2021), OpenAI $40B round (2025), Multiple infrastructure deals
• LinkedIn: Coatue
• Sector Focus: Infrastructure, enterprise software, fintech, AI
• Stage Focus: Series C, Series D, late-stage, growth
• Location: New York City, United States
• Website: coatue.com

14. General Catalyst

General Catalyst backed Stripe early and continues investing in developer infrastructure. They understand API-first business models.

• Recent Deals: Stripe early rounds, Vercel Series F (Sep 2025), Infrastructure portfolio
• LinkedIn: General Catalyst
• Sector Focus: Infrastructure, developer tools, API platforms, enterprise software
• Stage Focus: Seed, Series A, Series B, Series C
• Location: Cambridge, United States
• Website: generalcatalyst.com

15. Nexus Venture Partners

Nexus backed Postman from Series B through Series D. They focus on developer tools and infrastructure with Indian founders.

• Recent Deals: Postman Series B through Series D (2019-2021), Developer infrastructure portfolio
• LinkedIn: Nexus Venture Partners
• Sector Focus: Developer tools, API platforms, enterprise software, infrastructure
• Stage Focus: Series A, Series B, Series C
• Location: Menlo Park, United States / Bengaluru, India
• Website: nexusvp.com

16. Kleiner Perkins

Kleiner Perkins invested in Stripe Series C and backs infrastructure companies with strong technical teams. They understand deep tech.

• Recent Deals: Stripe Series C (Jul 2015), Chainguard $612M total funding (2025), Infrastructure portfolio
• LinkedIn: Kleiner Perkins
• Sector Focus: Infrastructure, developer tools, enterprise software, deep tech
• Stage Focus: Series B, Series C, Series D
• Location: Menlo Park, United States
• Website: kleinerperkins.com

17. Y Combinator

YC backed Stripe in 2010 and Super API in 2023. They fund developer tools at seed stage and have the batch network to help scale.

• Recent Deals: Stripe seed (2010), Super API $500K seed (2023), Thousands of developer tools in batches
• LinkedIn: Y Combinator
• Sector Focus: Developer tools, API platforms, infrastructure, all categories
• Stage Focus: Seed
• Location: Mountain View, United States
• Website: ycombinator.com

18. Founders Fund

Founders Fund invested in multiple Stripe rounds. Peter Thiel's firm backs infrastructure that others think is too technical or too early.

• Recent Deals: Stripe multiple rounds through 2025, OpenAI $40B round (2025), Infrastructure portfolio
• LinkedIn: Founders Fund
• Sector Focus: Infrastructure, deep tech, API platforms, developer tools
• Stage Focus: Seed, Series A, Series B, Series C, growth
• Location: San Francisco, United States
• Website: foundersfund.com

How Ellty helps API startups track investor engagement

These 18 investors closed deals from 2023 to November 2025. Before you start reaching out, set up proper tracking.

Upload your deck to Ellty and create a unique link for each investor. You'll see exactly which slides they view and how long they spend on your financials. Most founders are surprised to learn investors skip their market size slides but spend 5+ minutes on unit economics. When investors look at your API request graphs three times, you know they're serious.

When investors ask for more materials, share an Ellty data room instead of messy email threads. Your cap table, financial model, and API documentation in one secure place with view analytics. You'll know who's actually reading your technical architecture docs versus who just clicked once.

Common questions

How do I know if an investor is still active?

Check their recent deals on Crunchbase or Pitchbook from the last 6 months. If they haven't closed anything in a year, they're probably between funds. Look at their portfolio page - active investors update it regularly.

Should I cold email investors or get introductions?

Warm intros work better, but they're not required for API infrastructure. If you have strong metrics (100K+ API calls daily, 120%+ net retention), cold emails to the right investor work. Skip the generic ones.

What's the difference between seed and Series A API investors?

Seed investors bet on team and vision. They'll fund you at 1000 API calls per day. Series A investors need usage proof - typically 1M+ monthly requests and paying customers. Some seed firms do Series A, but check their actual check sizes.

How many investors should I reach out to?

20-30 targeted investors who've actually funded API infrastructure. Don't spray and pray. Use Ellty to track which investors engage with your deck. Follow up with the ones who spend time on your metrics.

When should I set up a data room?

Before your first investor meeting. Seriously. When they ask for financials, cap table, or API docs, you want to share instantly. Ellty data rooms let you add docs as conversations progress. Start with basics, add technical details when they ask.

Do investors actually care about pitch deck analytics?

Yes, when it speeds up their process. Investors who see you're tracking engagement know you understand metrics. Plus, you'll know which slides confuse them - if every investor skips your architecture slide, it's probably not clear enough.