Gustaf Alströmer

general partner @ycombinator. previously product @airbnb

[Nicolas Dessaigne @dessaigne]

I'm hosting a happy hour in Paris on June 30 for ML researchers in academia and industry. If you’re technical staff at a research-focused org, come meet others working at the frontier!

[Tom Blomfield @t_blom]

I'm excited to be back in Paris on June 29th for @ycombinator Startup School.

We'll be joined by the founders of some incredible companies; PostHog, Datadog, Supabase, AMI, and more.

Link in thread to apply for a ticket.

[Y Combinator @ycombinator]

Back in 2023, Max Junestrand was a college student in Sweden with a McKinsey offer in his back pocket. Instead, he and his two co-founders went all in on legal AI and built @WeAreLegora (YC W24) into one of the fastest-growing enterprise companies in history. In just 18 months, Legora surpassed $100M in ARR.

Today, the company is one of Europe’s most valuable AI startups, recently valued at $5.6B, with nearly 500 employees serving 1,000+ law firms and legal organizations across 50+ markets.

In this fireside with YC's @gustaf at our Stockholm event in April, @MaxJunestrand shares how Legora found its way into legal AI, why it moved so fast after YC, and how it convinced one of the world's most conservative industries to embrace a new way of working. He also digs into fundraising, competing in the age of foundation models, scaling a founder-led culture, and why Legora's ambition goes far beyond legal tech.

00:00 —Max Junestrand, CEO of Legora
03:11 — Starting Out: What Were You Thinking?
04:36 — Risk, McKinsey Offers & Taking the Leap
05:37 — Getting Into YC
07:06 — Arriving With Imposter Syndrome
09:59 — The YC Fundraise Grind
11:31 — Staying Confident Through the No's
12:00 — Building the Next Google From Europe
14:25 — Mini Games & the Product Manifesto
16:28 — $100M ARR, 500 People, Going Global
19:15 — M&A Agents Doing the Actual Work
20:41 — What If OpenAI Does This?
21:27 — Finding Your Moat as Models Get Smarter

[Lenny Rachitsky @lennysan]

So much alpha right now in being Codex / Claude Code’s tool of choice

[Aaron Epstein @aaron_epstein]

There's a new playbook being written right now for running an AI-native service business, and @charliewarren is at the frontier. Great advice here for how to do it right.

[Y Combinator @ycombinator]

Some of the biggest companies of the next decade won't be software businesses. They'll be services companies like insurance carriers, law firms, and tax practices rebuilt from scratch with AI doing most of the work.

In this episode of Startup School, YC Visiting Partner @CharlieWarren walks through the playbook for building AI native services companies, covering how to pick a market with the right traits, why variance kills these businesses faster than anything else, and the P&L math that’ll transform your business model.

00:00 — Intro to AI Services Companies
01:01 — Picking the Right Market
02:55 — Markets YC Likes Right Now
03:43 — The Sam Altman Test
04:35 — The Right Founding Team
05:28 — Building the Product
06:19 — Variance Is the Existential Problem
07:08 — The Early Demand Trap
07:53 — How to Price AI Services
08:41 — The P&L Walkthrough
09:33 — AI Operating Leverage
10:27 — Don't Buy Your Way In

[Derek Thompson @DKThomp]

This has quietly been a miracle month in medicine.

In the last 5 weeks we’ve got news on:

- retatrutide, the triple agonist GLP-1 from Lilly, basically melting fat and body-wide inflammation at record levels
- RevMed’s new pancreatic cancer drug showing unprecedented abilities to extend life
- small trial of a one-and-done PCSK9 gene editing therapy for slashing LDL cholesterol
- Mayo’s AI-assisted radiology showing vastly improved cancer detection
- this new therapy for metastatic solid tumors

This stuff is at varying levels of evidence. Retatrutide is ~100% on its way, other stuff needs more clinical trial data. But put it together and we’re maybe on the verge of majorly reducing the mortality of heart disease and cancer, the two leading causes of death in America.

[Leila Clark @leilavclark]

Everyone is ragging on Jared for this, but he’s absolutely right

AI agents *are* incredibly productive with prod db access.

If you’re a vibe coder with no idea how a database works, this is obviously insane. But if you’re a professional software engineer and systems thinker like Jared, you’ve already set up guardrails and best practices so your agent doesn’t do anything bad.

eg you probably have backups, you’ve set up docs/an md file to define prohibited actions, you probably use an ORM defined in code… and if an incident happens, you do a post mortem and figure out how to improve your system

This is all stuff we’ve been doing for decades. And Claude is much smarter than the average new dev!

[Gustaf Alströmer @gustaf]

@karrisaarinen @ycombinator @SlackHQ I think that's a hard question to answer in general terms. In some cases, go all in on replacing all bad software in your category (since building is faster now). In other cases, not. But I think the companies that are doing the best are building more than before

[Gustaf Alströmer @gustaf]

The degrading of @SlackHQ is in full force. If there is one thing I've learned about messaging apps is that reliability (real and perceived) is #1. Slack isn't meeting the bar anymore.

It also seems like PM's there have been tasked with driving engagement and as a result are adding lots of new useless notifications. If you have strong reliability you don' t need that. Whatsapp is a great example.

[Gustaf Alströmer @gustaf]

We’re intense power-users of Slack at YC. Not holding out for alternatives but expecting the product to improve and not get worse - which is my personal experience sadly. We use it so much anything that worse the experience is noticed. We have many workspaces and use all the customizations they provide.

[Tymofiy Mylovanov @Mylovanov]

Petraeus: Putin is the personification of evil.

He wants to reassemble as much of the former Soviet Union or Russian Empire as he can, and he does not believe Ukraine has a right to exist as an independent country. We did not listen carefully enough. 1/

[Gustaf Alströmer @gustaf]

Claude thinks you are probably right re uptime:

Bottom line for your original claim: Your experience is real and well-supported — Slack tells you when things break, WhatsApp doesn't, which is the entire UX gap. But "Slack is more reliable" in raw uptime terms isn't strongly supported by data; both have hours of downtime per year. The honest version of your argument is "Slack has better failure transparency," not "Slack has better uptime."

But their UI is not getting better... :)

[Gustaf Alströmer @gustaf]

@karrisaarinen @sreikanth @ycombinator @SlackHQ I don't understand the value of this. And why it doesn't clear out when i've read the messages

[Gustaf Alströmer @gustaf]

@karrisaarinen @ycombinator @SlackHQ What is the most reliable messaging app you are using?

[Gustaf Alströmer @gustaf]

@karrisaarinen @ycombinator @SlackHQ I'm experiencing reliability issues with Slack. Message's aren't sent. Messages can't be deleted. App not loading properly. I haven't had any of those issues with Whatsapp ever to be honest.

Messages on iPhone is even worse. It's nearly unusable for me.

[Y Combinator @ycombinator]

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

[Ankit Gupta @agupta]

my prompt for aspiring founders: assume the models reach superintelligence (arguably they have already), don't kill us all, and still require us to prompt them to do things.

what are the hardest problems you can now point them at?

[Pete Koomen @koomen]

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!