Monumental Labs
Monumental Labs is building AI-powered robotic stone-sculpting factories. It was founded in 2021 by former Silk co-founders Salar al Khafaji (CEO) and Sebastiaan Visser and is headquartered in Mount Vernon, NY. In February 15 2024 the company raised a $25 million round co-led by Plural and Hummingbird, with participation from Northzone, Foundamental, NP-Hard Ventures and Material Ventures, to accelerate deployment of its bricklaying and stone-carving robots.
Monumental Labs
Physical Intelligence
Physical Intelligence is developing π0, a foundational AI model that can control any robot. The San-Francisco startup was founded in 2024 by robotics researchers Karol Hausman, Sergey Levine, Brian Ichter and Chelsea Finn. On November 4 2024 it raised $400 million at a $2 billion valuation from Jeff Bezos (Bezos Expeditions), OpenAI, Thrive Capital and Lux Capital and is now hiring extensively in robotics, ML and infrastructure while showcasing household-task demos such as folding laundry.
Patina Systems
Patina Systems is building “spontaneous software”—every-day tools that any user can instantly customize and share—aiming to blur the long-standing line between “consumer” and “developer.” The New-York startup was founded in 2024 by Tyler Angert (ex-first designer at Replit, MIT Media Lab researcher). Patina closed an undisclosed day-one seed round on Sept 17 2024, backed by Air Street Capital, Haystack, Cursor Capital, 2392 Fund and angel investor Soleio. The team is currently hiring iOS-focused design engineers and full-stack AI engineers in NYC.
Todd Berman
A repeat technical founder and engineering leader “building something new” in stealth. Based in San Francisco and operating in pre-launch mode (founded 2024 according to StratIntel), Berman most recently served as CTO at Attentive (promoted March 2022 after scaling the SMS-marketing platform’s infra) and previously co-founded Braid (shared-wallet fintech) and EveryTeam, and held VP Engineering roles at GitHub and the NFL. His next venture has not yet announced a name or funding. Currently in Stealth 👻
Cora
Cora is an AI “chief-of-staff” that triages your inbox, drafts replies in your voice, and twice-daily briefs everything else. Incubated inside media/AI studio Every, the tool was built end-to-end by entrepreneur-in-residence Kieran Klaassen and launched to the public in December 17 2024; the startup lists Dan Shipper (Every’s co-founder/CEO) as co-builder and advisor. Cora remains subscription-funded—no outside capital disclosed—as the NYC- & SF-based team grows its 2,500-user beta into a $15-per-month SaaS product.
Synthelix AI
Synthelix AI is designing a DePIN (Decentralized Physical Infrastructure Network) that provides GPU compute and infra rails for on-chain AI agents. Founded in 2024 and headquartered in San Francisco, the privately-held project is led by CEO Oliver Smith and a 10-person core team (Nsikak Joseph – Community, Bella Garcia – Ecosystem, etc.). It recently opened its Syn GPT test-net, claims 740 k+ active nodes, and prepares the $SYNAI token plus Jessie OS agent marketplace; no venture financing has been announced to date.
Den
Den is a Slack-/Notion-style workspace “where humans and agents collaborate” — every channel, doc and workflow can be staffed by your own LLM agents. The YC Spring 2025 startup was founded in 2025 by Linus Talacko (ex-Lyrebird Health) and Justin Lee (ex-Atlassian) and is headquartered in San Francisco. Den took the standard $500 k YC post-money SAFE in April 2025 and is now courting design-partner teams while hiring full-stack engineers to scale its agent framework.
Shrinked.ai
Shrinked.ai is building a “conversation protocol for the AI era,” turning raw calls, podcasts and meetings into timestamp-attributed, queryable context so LLMs can cite their sources. Founded in 2022 by New York creator-operator Vanya Cherepukhin, the privately-held company is based in New York City and remains bootstrapped; it opened a closed beta last month for its Capsule context-clipboard product and lists fewer than ten employees on LinkedIn.
Sim Studio
Sim Studio is an open-source canvas for designing, testing & deploying agentic workflows in minutes. The YC Spring 2025 startup was founded this year by Emir Karabeg (CEO) and Waleed Latif (CTO) and operates fully-remote from a San-Francisco base. Sim Studio is still pre-seed, having taken only the standard Y Combinator $500k SAFE in January 2025; the two-person team is courting design-partner pilots while open-sourcing its “Sim” runtime on GitHub.
Sim Studio
Cotool
Cotool gives security-ops teams AI agents that stitch together context and automate repetitive investigations. Founded in 2025 by Logan Carmody (CTO), Eddie Conk (CPO) and Max Pollard (CEO), the three-person company went through YC Spring 2025 and is headquartered in San Francisco. Cotool has disclosed only the standard Y Combinator $500k deal in April 2025 so far and remains in private beta with a handful of design-partner SOC teams.
Hyperspell
Hyperspell is building an end-to-end RAG-as-a-Service data platform that lets developers connect dozens of SaaS sources and serve clean, AI-ready data via a single API. The San-Francisco company was founded in April 2024 by Conor Brennan-Burke (CEO) and Manu Ebert. In March 2025 it closed a $1 million pre-seed round led by angel investors Lisa Yu (ex-On Deck), Julian Weisser (Kepler Operator’s Fund) and Siqi Chen.
Mainframe
Mainframe is designing “interfaces for the future”—starting with Cobot, a proactive AI teammate that anticipates user needs. The startup was created in 2024 by prolific designer-founder Jordan Singer (ex-Figma, Diagram) and is headquartered in San Francisco. Mainframe has raised $15.5 million to date, recently a $10m series a (Dec 2024) backed by Base Case Capital, Stellation Capital, Lachy Groom and Peter Boyce (Stellation Capital) with angels such as Akshay Kothari (Notion), Alana Goyal and Weekend Fund.
Sylvan Labs
Sylvan Labs is creating the first digital “account-manager” agent that analyses customer data post-sale, surfaces upsell opportunities and executes follow-through tasks for revenue teams. The South-Park (SF) startup was founded in 2025 by Charles Li (ex-Vista Equity & Bessemer investor) and Shangyan Li (ex-Butter CTO) and has raised a $2 million pre-seed round from unnamed “top investors,” according to recent founding-engineer job posts and referral announcements.
Ahmad Beirami
Ahmad Beirami is an AI-safety researcher (PhD Georgia Tech) who spent the past three years at Google DeepMind working on controlled decoding and reward calibration for LLM alignment. In June 2025 he announced his departure to “explore agentic applications,” signalling a new, stealth venture from his base in New York City.
Roi Tiger
Roi Tiger, co-founder of mobile-analytics startup Onavo (acquired by Facebook in 2013) and former VP Engineering at Meta (2013-2022), is now building an as-yet-unnamed stealth cybersecurity company from Tel Aviv. ~3 months ago he quietly closed a US $20 million seed from Sequoia Capital, Index Ventures and Cyberstarts and is currently finalising a US $55 million Series A led by Greenoaks, which would value the company “in the hundreds of millions” even before launch.
Taskmaster AI
Taskmaster AI is an open-source Model-Control-Protocol (MCP) server that turns a product-requirements document into a dependency-aware task graph so AI agents (Claude, GPT-4o, etc.) can execute software projects reliably. The tool was created in March 2025 by serial operator Eyal Toledano and has rocketed to 17 k★ on GitHub and 5 k stars in its first 30 days. Toledano (CEO) is commercialising Taskmaster from a San-Francisco base, hiring two founding operators, and financing development through GitHub Sponsors while preparing a first institutional seed.
Falconer
Falconer is building an AI-powered knowledge platform for engineers: it ingests code, docs, Slack threads and more, then keeps them fresh and searchable with autonomous agents that can also draft onboarding guides or run code-review checklists. The San-Francisco company was founded in 2024 by Maximiliano Benedetto (ex-Meta GenAI, Uber) and David Núñez (ex-Stripe knowledge-infra lead). In February 25 2025 Falconer quietly raised a seed round (amount undisclosed) led by The General Partnership with participation from Xtripe Angels (Stripe-alumni syndicate) and Coughdrop Capital; founder-backers have since been recruiting a founding AI-engineer via Ashby.
Mechanize
Mechanize wants to supply the data and evals that let AI agents do any desk job. Founded in April 2025 by Tamay Besiroglu, Matthew Barnett and Ege Erdil (all ex-Epoch AI researchers), the team is headquartered in San Francisco and operates fully remote. In its launch essay on April 17 2025 the startup disclosed an undisclosed seed backed by Nat Friedman & Daniel Gross’s fund, Patrick Collison, Dwarkesh Patel, Sholto Douglas and Marcus Abramovitch. Mechanize is now hiring software engineers to build simulated work environments that will train RL agents and provide benchmarks for “automation of the whole economy.”
Today we’re announcing Mechanize, a startup focused on developing virtual work environments, benchmarks, and training data that will enable the full automation of the economy.
— Mechanize (@MechanizeWork) April 17, 2025
We will achieve this by creating simulated environments and evaluations that capture the full scope of…
Inflight
Inflight gives product designers rapid, high-quality async critiques: share a Loom-style walkthrough plus your Figma file and get timestamped video feedback from senior designers within hours. The company was founded in 2024 by long-time design educator Michael “Ridd” Riddering, along with Kyle Barber and Veer Gadodia, after graduating from the South Park Commons residency. Inflight raised a seed round by Chapter One and South Park Commons. Now inviting early-access teams while Ridd publicly iterates on the product each week via LinkedIn posts.
The Browser Company
The Browser Company, maker of the Arc browser, wants the browser—not the OS—to be the new productivity platform. Founded in 2019 by Josh Miller (ex-Obama WH digital director) and Hursh Agrawal, the New-York startup has raised $128 million across several rounds, most recently a $50 million Series B on March 21 2024 led by Pace Capital, valuing the firm at $550 million. Other backers include Salesforce Ventures and prominent angels such as LinkedIn’s Jeff Weiner and Medium’s Ev Williams. The 80-person team is shipping Arc on macOS, Windows and iOS and recently launched Arc Search with “Browse for Me” AI summarisation.
Theta Software
Theta builds the memory layer that lets AI agents learn from every run. The Spring-2025 YC company was founded by Rayan Garg, Tanmay Sharma and Gurvir Singh and operates from San Francisco. Its four-line SDK stores trajectories, analyses mistakes and feeds optimisations back on the next call; in early tests it boosted OpenAI Operator accuracy by 43 % with seven-times fewer steps. Theta accepted the standard $500 k YC post-money SAFE in June 2025 and is now hiring its first external engineers.
Theta Software Inc.
Keycard
Keycard provides dynamic, task-scoped credentials so agents, tools and services can interact securely without long-lived API keys. Founded in 2025 by Matt Creager (ex-Vercel DevRel), Jared Hanson (creator of Passport.js) and Ian Livingstone, the startup is headquartered in San Francisco. In February 2025 a Hacker News job post called it a “newly-funded company”; Exceptional Capital and Tapestry VC as backers, but the May-2025 round size remains undisclosed. Keycard is recruiting founding systems, AI and frontend engineers while running an early-access programme at keycard.sh.
