Morning VC Brief丨2025.10.31

Week44 Highlights丨Mercor, Whatnot, Fireworks AI, Mem0, Sumble, Crustdata, Sublime, Vesence

Author

eric gu
October 31, 2025

Morning VC Brief is an expert daily curation of tech and venture news. Feel free to forward; the sign-up is here

Table of Contents

01. Venture News

1/ AI Talent Marketplace Mercor Raised $350M Series C at $10B

  • Product: Platform connecting human experts with AI labs and enterprises to train frontier AI models through knowledge sharing and workflow codification

  • Highlight: 5x valuation increase from Series B; vast expert network training AI models in specialized domains (medical, financial, legal)

  • Investors: Felicis (Lead), Benchmark, General Catalyst, Robinhood Ventures

  • Source

2/ Live Shopping Platform Whatnot Raised $225M Series F at $11.5B

  • Product: Live streaming e-commerce marketplace connecting buyers and sellers across the US, UK, and Europe for collectibles and various categories

  • Highlight: 2025 GMV already surpassed $6 billion, more than double all of 2024

  • Investor: DST Global and CapitalG (Co-lead), Sequoia Capital, Alkeon Capital

  • Source

3/ AI Inference Platform Fireworks AI Raised $250M Series C at $4B

  • Product: AI inference cloud enabling enterprises to build, tune, and scale highly optimized generative AI applications using open-source models

  • Highlight: processes over 10 trillion tokens daily for 10,000+ customers in 2025; inference speeds up to 12x faster than vLLM and 40x faster than GPT-4

  • Investor: Lightspeed Venture Partners, Index Ventures, Evantic (Co-lead), Sequoia Capital

  • Source

4/ AI Memory Layer Platform Mem0 Raised $24M Series A

  • Product: Open-source API and memory framework enabling AI systems to remember past interactions across apps and agents, compatible with OpenAI, Anthropic, and open-source LLMs

  • Highlights: 41,000+ GitHub stars; 13M+ Python package downloads; API calls grew from 35M in Q1 to 186M in Q3 2025 (30% MoM growth); 80,000+ developer signups

  • Investor: Basis Set Ventures (Lead), Peak XV Partners, GitHub Fund, Y Combinator, Kindred Ventures

  • Source

5/ AI-Powered Sales Intelligence Platform Sumble Raised $38.5M in Seed and Series A

  • Product: Sales intelligence platform using AI-powered knowledge graph to surface contextual company data including technographic information, organizational charts, tech adoption signals, and decision-maker contacts

  • Highlight: 19 enterprise customers including Snowflake, Figma, Wiz, Vercel, Elastic; tens of thousands of users; 30% Pro subscription rate

  • Investor: Coatue (Seed lead, $8.5M), Canaan Partners (Series A lead, $30M), AIX Ventures, Square Peg

  • Source

6/ Real-Time Data Infrastructure for AI Agents Crustdata Raised $6M Seed

  • Product: Real-time data platform using live web crawlers to continuously monitor and organize business and individual data, turning the internet into structured, machine-readable resources for AI agents in sales, recruiting, and investment

  • Highlight: revenue scaled from $770K to $4M+ in 7 months with zero outbound marketing; achieved profitability with one-person sales team

  • Investor: Y Combinator and A Capital (Co-lead), General Catalyst, SV Angel

  • Source

7/ AI-Powered Email Security Platform Sublime Raised $150M Series C

  • Product: Email security platform with AI agents including Autonomous Security Analyst (ASA) for triaging user reports and Autonomous Detection Engineer (ADÉ) for auto-adapting threat coverage

  • Highlight: Customer base grew 4x in 2025; zero enterprise customer churn since inception; platform autonomously adapts to each organization's unique environment and evolving threats with transparency and control

  • Investor: Georgian (Lead), Avenir, 01A, Jon Oberheide, Index Ventures

  • Source

8/ AI Agent Platform for Law Firms Vesence Raised $9M Seed Round

  • Product: Builds AI agents that review documents, emails, and projects directly within Microsoft Word and Outlook, focusing on error-checking against firm best practices.

  • Highlight: Achieved 90% weekly active usage in initial rollout; offers superior user experience vs. MS Copilot via technical breakthroughs in Office integration and unique focus on review/improvement over content generation

  • Investor: Emergence(Lead), Y Combinator, 20VC

  • Source