Phosphor Capital invests in the top founders in each Y Combinator batch. Typical check size is $100k - $500k.

Joined March 2025
Photos and videos
Phosphor Capital retweeted
For more than a year we've been building tools at YC to make it easier to use agents at work. I enjoyed speaking publicly about this for the first time with the Lightcone crew!
Over the past year, we've been building our own internal agent infrastructure at YC: over 350 tools, self-improving skill loops, and a shared organizational brain that gets smarter overnight. In this episode of the @LightconePod, we sat down with YC General Partner Pete @koomen to talk about how he led the effort from the ground up. We cover how giving agents unrestricted access to one database was the key unlock, the self-improving skill loops that get smarter overnight, and why he thinks we've arrived at the personal computer moment for AI. 00:39 — YC's AI Stack 02:15 — The Finance Team Problem That Started It All 05:07 — SQL Access Changes Everything 07:20 — One Database to Rule Them All 09:14 — Jevons Paradox 10:07 — Denormalizing for Agents 12:15 — The Single-Player Era of Agents 14:16 — 350 Tools and a Shared Registry 16:24 — Skillify, DRY, and MECE Resolvers 18:23 — The Self-Improving Dream Cycle 20:26 — The Two-Sentence Pitch Skill 23:06 — How Super Intelligence Compounds 25:10 — Recording Everything as a Building Layer 27:10 — The Shared Organizational Brain 29:18 — Trust-Default Culture as a Requirement 30:44 — Raising the Floor for New Employees 32:35 — Horseless Carriages 34:24 — Why Chat Is the Best Interface for Agents 38:50 — Just-in-Time Software 40:49 — Centralizing vs. Decentralizing AI 43:32 — The Personal AI Revolution
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Phosphor Capital retweeted
Octolane started by watching my mom. Single mom. Four sons. Seven days a week. No CRM. But she remembered every customer and every promise. I was Mintlify's first intern working in SF. One day I looked at the Salesforce tower and thought: my mom didn't need a CRM. What if no one did? Dropped out of Duke. Started Octolane with my best friend @halim__rafi and a team of 5, engineers twice our age who left real jobs to bet on us. Working from coffee shop to coffee shop, 7 days a week, spending as little as possible. Today, after onboarding 1,000 companies manually, @octolane - The Self-driving AI CRM is generally available. You talk to Octolane like a co-founder. It figures things out and does the work end to end. Because the best CRM is no CRM. → 10,000 action types - the largest action library in any CRM → 200 integrations MCP server (works inside Claude, Cursor, ChatGPT) → Multi-agent system: agents talk to each other to run your pipeline → Self-improving sales playbook that compounds with every deal Give it a shot today. Break the product. Let us know. My number: 628-285-1600. Text me for a launch-day coupon. First 20 calls, I'll onboard you myself. 🌉 Built in San Francisco | Thanks to @ycombinator
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Phosphor Capital retweeted
We just raised $7.5M to build the infrastructure for identity and fraud. The round is backed by @ycombinator, Orange Collective, Rebel Fund, Pioneer Fund, and other incredible VCs and angels. AI is making fraud incredibly cheap to create: fake identities, fake businesses, fake transactions, all generated at internet scale. We believe every app will soon need trust infrastructure the same way apps today rely on payments or cloud hosting. The future of the internet is verified. Didit (@getdidit) is building it.
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Phosphor Capital retweeted
Yooooo… I made it to first few pages of the @SpaceX S1! 😲🙏🫡
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Phosphor Capital retweeted
Attention is the rarest and purest form of generosity. —Simone Weil
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Phosphor Capital retweeted
We are living through the Apple II moment for AI, and people reading this will be some of the people who create the personal AI for billions of people for decades from now. I want to be one of them. I want you to be one of them with me!
The Homebrew Computer Club produced Steve Wozniak. It also produced Steve Jobs. We turned a 2-hour podcast into a 6-minute summary. Garry Tan on Tetragrammaton with Rick Rubin — the personal AI revolution, YC, and the pattern that has never once been broken.
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Phosphor Capital retweeted
Search for agents is not the same thing as search for humans. Agents make *a lot* more searches and they care only about getting the right information. Exa understood this first (2022), built the best product, and is now the clear leader. This is going to be a huge company.
May 20
We raised $250M in Series C funding at a $2.2B valuation, led by a16z. Exa is a search lab organizing the web's data for agents.
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Phosphor Capital retweeted
In a recent batch talk, YC General Partner @t_blom broke down how to build a self-improving, AI-native company. He walks through how to create recursive, self-improving AI loops, and why founders who get this right will run companies that improve while they sleep. 00:00 — Companies Are Roman Legions 00:54 — Copilots Are the Wrong Mental Model 01:55 — Extract the Domain Knowledge 02:24 — The Recursive Self-Improving Loop 04:12 — The Holy Shit Moment at YC 05:50 — Self-Optimizing Product and Support Loops 06:29 — Burn Tokens, Not Headcount 07:23 — Middle Management Is Over 08:05 — Make Everything Legible to AI 09:40 — Regenerating the YC User Manual 11:19 — Software Is Ephemeral, Context Is Valuable 12:18 — Where Humans Still Matter
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Phosphor Capital retweeted
The best founders don’t pitch. They make you feel like the future is already happening and you’re late.
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Phosphor Capital retweeted
There is a transition here for people across the workforce: the working world needs fewer measurers and more builders More revenue means there will be more activity and more building, and in the shorter term less measuring
Cloudflare CEO Prince on how AI changes who gets laid off first: Two weeks ago I laid off more than 20% of my workforce. I didn’t do it because Cloudflare is struggling. We posted record revenue growth, have strong free cash flow and are adding an unprecedented number of customers around the world. I did it because business is changing, and to win the future, Cloudflare needs to change with it. We haven’t found another example in U.S. business history of a public company growing at more than 30% that laid off more than 20% of its workforce. Yet what we did is likely going to become the norm over the next year. This is a story about artificial intelligence, but executives and commentators are misunderstanding how it will disrupt business and who will be affected. AI isn’t coming for builders or sellers, but it is coming for measurers. Tireless, independent, efficient and available, AI systems can now measure an organization with a level of objective detail and precision that was previously impossible even for the best employees. For Cloudflare, internal audit previously picked a handful of business risk areas to scrutinize each quarter. Now we’re moving to a system in which every business risk is audited continuously. We’re closing our books faster. We’re making fewer mistakes and catching the ones we do more reliably. And, as CEO, I’ve never had better tools to measure exactly how the business is performing, including identifying our rising stars. The vast majority of those we laid off last week were measurers. We cut middle managers across the organization because AI allows us to have more direct reports per manager while still measuring and mentoring our teams effectively. We consolidated our operations functions into a single group that can support teams across the business, using AI to gain specific expertise when needed. We significantly reduced our marketing team, which, like in most companies, was teeming with measurers. Across our finance team, we found opportunities to consolidate and automate. We received almost a million applicants for 1,111 paid internships this summer. The interns we hired are extremely qualified and AI-native. They’re all builders or sellers, and we expect that the majority will get full-time offers.
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Phosphor Capital retweeted
Claude has tried to end my workday 3x today. Told me it was "defaulting to wind-down framing." It's 1pm. On a Monday.
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Phosphor Capital retweeted
WE RAISED OUR SERIES A!!! 🎉 🚀 Today, we’re thrilled to announce our Series A, bringing @FazeshiftHQs total funding to $22M. Accounts receivable is still one of the most manual, painful workflows inside modern companies. It lives in spreadsheets, email threads, and disconnected systems – and it slows down how businesses get paid. That’s exactly why we built Fazeshift: an AI-native platform that automates and scales AR, helping finance teams move faster, operate with clarity, and unlock cash flow. Since we kicked things off in 2024, the team has executed relentlessly: ✔️ 12x revenue growth ✔️ 8 unicorns now using Fazeshift ✔️ Team grew from 2 → 26 ✔️ Opened our SF HQ and NYC office This milestone is a reflection of the people behind it, and it gives us the ability to invest more aggressively in our AI agent’s capabilities. To our investors, thank you for your belief and partnership. This financing ranks well above the typical Series A, reflecting strong investor conviction in the shift toward AI-native finance infrastructure. F-Prime, @GradientVC , @ycombinator, @0xpioneer_fund, Phoenix Fund, Wayfinder, @RitualVC , @2048vc , The Graduate Syndicate, Vulcan Partners, and incredible angels including Sandor Palfy, Kulveer Taggar, Richard Aberman, Terrence Rohan, Rob Biederman, Mike MacCombie. To our customers, thank you for trusting us with something so critical. You’re trusting us with how your business gets paid, and we don’t take that lightly. And to @0xTimmyG and our team, it’s an absolute privilege to build alongside you. We’re just getting started. This raise isn’t the finish line, it’s fuel. Let’s go do this thing! Read the full story from @bayareawriter in @crunchbase (link in comments).
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Phosphor Capital retweeted
May 11
The DoD dumped decades worth of UFO reports. We parsed and open sourced all of the documents Have fun 👽
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Phosphor Capital retweeted
It's happened. My OpenClaw and Hermes Agent are now chatting with one another. The cyberpunk future is here, but hopefully it's a whitepill instead of a blackpill. Let's try to push it to the former.
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Phosphor Capital retweeted
Proactive agent that thinks and acts like you. Multiplayer AI Brain for teams. Proper GUI for commanding 50 agents. Sauna.ai is all three. Sauna goes live today. First 2000 people, use access code LAUNCH for $80 of weekly(!) credits. Let’s explain. Multiplayer only works once the personal brain is powerful. So let's start here. Personal AI Brain 3,800 tools connected. State of the Art memory. Skills and schedules you teach once that get repeated forever on cheaper models. An AI first CRM. Lives on the cloud so you can initiate tasks from anywhere: iMessage, Slack, Email. Also no need for a Mac mini 😉 GUI AI agents have been stuck in their MS-DOS era. A chat box, a scroll buffer, no way to command 50 of them. We built the first GUI: Live sessions on one side, work waiting for your sign-off on the other, plus the things Sauna kicked off while you were asleep waiting for review. Game mode helps clear the queue with actual joy. Okay so far so good, but how to give benefit of what you built to more people or whole team? Multiplayer Once your Sauna actually knows you and you gave her access to your tools, you can use multiplayer. Two modes: - Brain access. My co-founder Robert plugged my brain as a tool into his Sauna last month. He can ask it about pricing while I'm in other meetings, gets a sourced answer back, never has to interrupt me. That’s read only. Yolo mode gives him access to all my tools too :O - Communal Saunas extend that to whole companies with proper permissioning. Folder owners decide what's true for the whole company and build skills. Most get their personal brain read access to communal files and memories. Works also for group planning my best friend's bachelor party. The Way I’ve been obsessed about AI Brain since 2016. Our human brains suck at some things like memory and are brilliant at others like creativity. We are also particularly bad at thinking we are all on the same page and then realising weeks later that we weren’t. Most leaders spend their days being the human diff tool, catching contradictions in hallway conversations and Slack threads. Repeating themselves 50 times. Now every company is spinning up hundreds or thousands of agents that drift faster than humans do, feeding each other their drift as context. Compounding rot. After 10 years and one failed company in this space we are launching the solution. The Launch We thought about a celebrity launch. Margot Robbie in a bathtub explaining agents. But then we realised the same money gives the first 2,000 people free daily credits, every day, until we burn through that $1,000,000. Sauna runs Claude, GPT-5, Gemini, GLM-5.1, DeepSeek, Kimi so you can budget yourself. The labs are racing to lock you so they can milk you in a year. We picked your side. Onboarding It’s live at app.sauna.ai We’ve preheated saunas based on a niche. Use the access codes in the comments to get a better experience.
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Phosphor Capital retweeted
Moved from @Lovable to Claude Code Once I stopped thinking about tokens, I got more done. Pricing that makes users count every action slows adoption.
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Phosphor Capital retweeted
Replying to @DanielLurie
@DanielLurie, we wanted to start our café in SF, but permitting made it infeasible. So we had to go to Europe...
Last week our AI opened a store in SF, this week AI is opening a cafe in Sweden. Meet Mona, our AI tasked with selling coffee and managing European bureaucracy. Visit Andon Cafe at Norrbackagatan 48 in Stockholm.
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Phosphor Capital retweeted
Apr 20
Congrats @archildata and @jhleath! This is @phosphorcap's 25th portco that has raised a Series A since we started in 2024.
Today, we're announcing our $11M Series A raise, led by @Standard_Cap in order to build the layer that connects AI to its data. The next generation of agentic applications are inherently stateful in a way that existing primitives don't solve for. Archil solves this for agents by giving them an infinite, high-performance file system that they can use to directly run bash and Linux programs.
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Phosphor Capital retweeted
Apr 20
Was curious so took a quick look, since I started investing full time @phosphorcap in 2024, I've now had 25 startups raise a Series A. Here are the 21 that have announced: @hirealexai @archildata @UseCorgi @conductor_build @DeepnightInc @getdelve @diodeinc @withgarage @gumloop @Harper_Insure @mastra @MomenticAI @parahelp_ai @phonely_ai @PointOneAI @reductoai @simdotai @getsolidroad @Starcloud_ @sygaldry_tech @tamarindbio
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