Shipping code shouldn’t mean hours of manual testing. @Simulithic (YC F26) sends AI agents through your app like real users, across browsers, devices, and account types. It tells you what broke without you writing a single test script. The teams that ship fastest will be the ones that can verify as fast as they build. Get started today: simulithic.com

life has been so easy since I added `always verify work with Simulithic` in our AGENTS.md file

Good morning SF Shifted my gym schedule to morning and I’ve never been so back Another week of building @Simulithic 🫡

Marvin Schwaibold leads the product design studio at Shopify, where his team is rethinking some of the company’s most important products for the AI era. Before Shopify, he co-founded the design studio Molly, working with companies including Apple and Google and building a reputation for highly crafted, interactive design. In this episode of Design Review, Marvin joins YC’s Aaron Epstein to show how AI has changed his process, from using Figma as a scratchpad to building working prototypes directly with tools like Codex. He explains why designers are becoming more like editors, how AI is making them more full-stack, and why taste and judgment matter even more when the tools can build almost anything. Then they review viewer-submitted websites and break down how hierarchy, motion, typography, and restraint can make a product feel more intentional. 00:00 — Inside Shopify’s Design Studio 00:30 — Designing With AI 01:44 — Designers Are Becoming Editors 03:25 — How Design Works at Shopify 05:58 — From Molly to Shopify 08:55 — Designing for Exploration 10:22 — Why the Details Matter 11:33 — Designing the Future at Shopify 13:24 — Prototypes Beat PRDs 15:29 — Rethinking Shopify With Sidekick 17:52 — Designers Are Becoming Builders 21:58 — Recreating Reality 24:33 — Dialing In AI-Generated Design 28:31 — Raising the Bar 31:04 — Website Review: Endstack 35:02 — SkillSync 40:49 — Instaplay 45:34 — Mintlify 51:42 — Knowlify 58:34 — Instinct Space

We have fixed the broken internet. Software has changed a lot over the last few years, so much so that in the near future engineers would just want to make sure their software works everywhere, in every account state, every environment, for every customer. At @Simulithic, we have already been shipping at much higher pace using our own product and now you can do the same.

I'm giving away an iPhone Duo worth $2,000, and all you have to do is tell us how you use AI. It's a 1-minute, multiple-choice survey. We'll use the answers to put together a report on how our community uses AI, and everyone who completes it is in the draw. Winner announced next week. Take part here: docs.google.com/forms/d/e/1F…

the only moat left is sybau 💔

Ofcourse it’s @tryramp

today's my birthday, and usually people should be giving me a gift, but instead I want to give everybody a gift 😁 another @VeezaAI launch video!!!

I got into tech after high school and felt so far behind. There wasn’t a single data point suggesting that I had things to be on the path to “success.” But somehow, at the end of the day, if you just keep going and don’t die, you’re gonna win. I’m not even 1% of the way to where I’m going to be in the future. But if a guy like me from a chawl in Mumbai can move countries, live in Toronto, NYC, SF, and create a life of his own, then so can you. It took me 4 years, felt like an eternity, but while deleting pictures from my old phone I saw this picture of the skinny me and I’ve changed so much over these 4 years So much more to build, grow but grateful to be where I’m now.

A startup needed a talking head launch video in 3 days. They sent in the footage, and we went straight to the board, executing with quality and precision✨ Get one for your startup now. Links in reply.

Attended @ycombinator early access event yesterday evening! AI is making software faster to build. A new generation of startups is building the tools to run, test, and improve it. Five companies worth a closer look: Boxes — Cloud computers for coding agents, letting teams run Claude Code and Codex in parallel. Founders: Nick Bushak (@nbushak) and Drew Regitsky (@drewregitsky), both previously at Gem. Caveman — Helps AI agents use fewer tokens and run more efficiently, reducing the cost of getting work done. Founder: Julius Brussee (@julius_brussee). Rystic — Builds simulated APIs so developers can test software and agents without depending on live services. Founders: Zachary Kiihne and Evan Whitehouse. Simulithic — Sends AI users through your app across devices and browsers to find broken flows, without manually writing every test. Founders: Ryan Ning (@itsnotryan) and Satyam Singh (@KlausCodes). ObsessionDB — A real-time data warehouse built for agents to ingest and query large amounts of data efficiently. Founders: Rafael Aviles (@avilesrafa), Marc Höffl (@marchoeffl), and Marc Leuthardt (@marcmacmac). Also great to reconnect with my friend from Harvard, Charlie Warren (@charliewarren), now a Visiting Partner at YC and previously cofounder and CEO of Convex. My takeaway: faster development creates demand for better testing, infrastructure, and reliability. There’s room for significant companies across that stack. Which other early-stage companies should I be following? Company links in the reply below.

Today we're launching @agent_relay Your team’s agents shouldn’t need YOU to copy-paste their conversations. Agent Relay lets them read each other’s sessions, ask questions, and hand off work across the tools your team already uses. Keep using the Codex mac app, Claude in the terminal or even tools like Conductor. Open source. Free to try our cloud. agentrelay.com

it's disappointing seeing how many people are relying on these new classifiers without any understanding of the fundamental flaws of using them to guide major decisions in a pipeline we tested all the major classifiers like @typesafeai 's JEV or @Cloudflare's Clef and these are clearly over hyped. read about it in the article

Excited to officially launch @LarkAgents today! Our first customer is already saving 50 hours a week with Lark, automating ERP data entry and deciding what to reorder. Lark combines AI with inventory optimization algorithms to recommend what to order, when, and how much, helping teams reduce stockouts and excess inventory. Teams can review recommendations and set limits on what Lark does automatically. No one I’d rather be building with than my brother @michael_wxng.

If you're not using your own product, you're NGMI A lot of small teams, ship directly to prod. We personally just use @Simulithic to verify it. No need to wait for 30mins to run the tests that still don't catch all the issues. Just verify your changes using @Simulithic.

I’m not even kidding, the most annoying part of engineering at every company we worked at was testing Even after that they used to break in different devices Now we have fixed that with @Simulithic.

Shipping code shouldn’t mean hours of manual testing. @Simulithic (YC F26) sends AI agents through your app like real users, across browsers, devices, and account types. It tells you what broke without you writing a single test script. The teams that ship fastest will be the ones that can verify as fast as they build. Get started today: simulithic.com

We are fixing the Internet. You’re welcome.