Phosphor Capital invests in the top founders in each Y Combinator batch. Typical check size is $100k - $500k.
San Francisco
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Phosphor Capital retweeted
Introducing Polly 🦜
Polly ships this fall. The app behind Polly:
1. 2.1M lessons completed, 2.3M+ min of Spanish immersed (4 years of Spanish immersion)
2. 31 min avg session (Instagram's global avg is 35)
3. Power users doing 5.5+ hrs/day
4. 620K+ learners
Get your own Polly. Link below.
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Phosphor Capital retweeted
Introducing Grade. Predict how users will respond before you ship.
Grade is an eval system calibrated to what real users actually say and do.
Get early access here --> voicepanel.com/grade
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Phosphor Capital retweeted
Introducing Pion, agents for running fully autonomous companies, any company.
We’ve used Pion to run vending machines, radios, stores, cafes & more. How much could Pion make running other companies? Find out yourself! Setup is trivial, the agents do the rest.
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Phosphor Capital retweeted
For a QSR, local competitor analysis is a vital part of setting prices and planning promotions.
Domino’s partnered with Brainbase to improve its competitor analysis agent from 41% to 97% accuracy while reducing cost per source by 52% across dozens of local markets.
Read more about how we got there below:
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Phosphor Capital retweeted
Today we're launching Asteroid Integrate!
Hundreds of pre-built healthcare integrations with the EHRs, payer portals and government systems that lack usable APIs.
If a human can use it, we can connect you to it. Live in days, not months.
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Phosphor Capital retweeted
Software engineering is becoming a hierarchy of loops. So today we're launching Mastra Factory: a system for agents to take software from issue into production.
Get started with 𝚗𝚙𝚖 𝚌𝚛𝚎𝚊𝚝𝚎 𝚏𝚊𝚌𝚝𝚘𝚛𝚢:
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Phosphor Capital retweeted
"Voice agents are built to be helpful. The problem is they can be too helpful and cross the boundary."
I sat down with @sumanyu, Founder and CEO of @HammingAI, at our @aiDotEngineer booth. @HammingAI stress-tests and monitors voice agents so the bank or hospital running one catches failures before a customer does.
Fresh after his talk “I Monitored Crime Audio. Voice Agents Scare Me More,” we got into:
0:00 how Sumanyu went from listening to 911 calls at Citizen to founding Hamming AI
0:39 why he's more nervous about voice agents than he was about crime
1:51 the first voice-agent security product
3:16 simulating messy reality: accents, background noise, code-switching
4:11 voice agents testing voice agents
5:47 why taking actions is table stakes, and what makes it dangerous
11:07 hot take: everyone rushed to B2B, more founders should build consumer
Thanks for coming to our @browserbase booth, @sumanyu!
Watch the full episode here:
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Phosphor Capital retweeted
Thanks for the @Starcloud_ and orbital data center feature @CNN! 🚀
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Phosphor Capital retweeted
today, we’re launching a new way to interact with Motion.
no more prompting & praying. just talk.
start with a simple message like "yo" or "what's trending on tech twitter today?"
@motion_so can do research, suggest assets, pull context from @github & @NotionHQ, propose ideas, and refine the creative direction with you.
this launch video is made entirely with Motion. 👇🏽
now available at motion [dot] so.
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Phosphor Capital retweeted
8 months ago, we shipped the first Pocket. Today, 100,000 people use it to be present in their most important conversations.
Grateful to have @Accel, @peakxvpartners, @ycombinator, @rauchg, @mati, and @nejatian behind us for what comes next.
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Phosphor Capital retweeted
AI writes all your code. Does it still work?
That's the gap: coding agents are scaling output, but the same with bugs and incidents. The biggest bottleneck is QA: how can you make sure the code your agents just wrote doesn’t break everything?
The best QA are the ones who know everything about your product. Today, we give that knowledge to Momentic’s most capable agent.
Every Linear ticket, every PRD in Notion, every PR - Momentic knows all.
In just the past few weeks, our agents analyzed 70k+ test failures and created 600 tests. Achieving a 73% PR merge rate, and it’s growing fast.
We’re grateful for the trust of our customers, including Notion, Xero, Webflow, Retool, Runway, Bilt, and more.
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Phosphor Capital retweeted
Today we're launching @mastra `Harness`
`Harness` gives you a `Session` with plan/build modes.
It lets you manage thread lifecycle, spawn or fork subagents, approve tools per-call or session, ask user questions, queue/steer.
With skills, sandbox, browser, heartbeat. channels:
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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 (@didit) 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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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.
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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