Today we started rolling out SimGym — a system that creates “digital customers” that behave like real ones. They browse your site, complete tasks, and reveal optimization opportunities. You can even run A/B tests with *zero* live traffic! Spent a year developing it.

This is absolutely one of the craziest things that we have ever shipped. You can use rollouts to A/B test your new idea and wait some weeks for results… or just use SimGym to simulate your customer and get results right now

Last quarter I rolled out Microsoft Copilot to 4,000 employees. $30 per seat per month. $1.4 million annually. I called it "digital transformation." The board loved that phrase. They approved it in eleven minutes. No one asked what it would actually do. Including me. I

This graph from pablo of Spanish fiscal contributions by age demonstrates an important fact. The 40 and 50 year olds are carrying both their kids and their parents. And not just economically. This is why it's hard to be middle-aged.

Year EIGHT as a founder CTO. 2025 felt like a decade. The year of vibe coding, Apple opening payments, almost getting acquired, saying no, scaling past 100 people, mistakes, cultural memes, and figuring out how to go long. miguelcarranza.es/cto-year-8

I'm Boris and I created Claude Code. Lots of people have asked how I use Claude Code, so I wanted to show off my setup a bit. My setup might be surprisingly vanilla! Claude Code works great out of the box, so I personally don't customize it much. There is no one correct way to

Después de unos días de trabajo hago pública CONTRATACIÓN ABIERTA, una web donde se pueden revisar de forma fácil los contratos menores de las administraciones públicas de España. Hay más de 7,3 millones de contratos y 11.700 organismos públicos. 👇👇 contratacionabierta.es

🇩🇪 Germany's Chancellor Merz says it was a 'serious strategic mistake to phase out nuclear energy'.

Editor: How’s the draft coming? Me, still “tightening” rewrite #24:

70K NO es un BUEN SUELDO, lo que PASA es que ERES POBRE 70K es lo mínimo aceptable para vivir de manera normal sin lujos en una ciudad. Si crees lo contrario, ENHORABUENA, te han lavado el cerebro. Eres pobre y no lo sabes, lo cual es muy triste. Hasta que la gente no se de

This needs to happen

Stop guessing. Test your store's next big idea with AI shoppers. SimGym is now available to all merchants on Shopify. apps.shopify.com/simgym

@levelsio For some reason, Spain is really good at this. Same or next day results. Cheap too. Best I've found anywhere in the world. Denmark on the other hand is horrendous at this. Week long wait for results.

The speed at which we adopt good ideas is impressive. So many wins this week with auto-research

Burning tokens so you don't have to! Just published more details on how SimGym works. Note the use of MIG - that's what enabled us to make it available for everyone.

Massive improvement to how Sidekick responds to complex prompts just rolled out. Cole and Alex Clark dream team.

Hay una brecha con la IA. Los que la usan de verdad. Alucinan, exploran y se preguntan qué es lo que se nos viene encima. Los que no la usan. Y no saben lo que se nos viene encima.

Alright, not Monday, but the single-theme SimGym is out! Now you can just run simulations against your current version and get recommendations.

If you are at #ICLR you can catch our talk about how we are building SimGym at Shopify. Also come to our booth. ta-conference.myshopify.com/pages/shopify-…

We keep optimizing SimGym, both in terms of quality and inference costs. So, we just doubled the number of free runs merchants get and halved the price for when those run out. I feel the number of free runs is sufficient for most merchants :-)