“don’t train your own model” is common ai advice. it's wrong. your token bill's the proof.
today, we’re excited to launch castform into open preview. castform is the easiest way for you to train your own model, on your own data.
open-weights models are performant and much cheaper. when trained on your task & proprietary data, they beat closed models. the thing standing between you and that was weeks of plumbing & years of ml expertise.
with castform, model training is as simple as prompt engineering. @castformai
bring your agent traces or raw corpora. castform turns it into training data, picks the right algorithmic recipes, manages gpus, and gives you an ide to watch and chat with your model as it learns.
see what you can build with castform👇
Alfred Lua retweeted
just tried using @booplet_apps to make a mini app for chess coordinates training
im not even good at writing prompts but it basically one-shotted ~90% of this right off the bat 🤯
Alfred Lua retweeted
Narrative violation: you can build a $1B+ startup while being remote and having a life & family outside of work.
At @linear we value quality & focus. We believe it comes from trust, ownership, and space to think.
Alfred Lua retweeted
Software isn’t just code. It is one of the cheapest, fastest ways to turn an idea into reality.
We’re building a different future where anyone can make and own their apps.
Because it was never about the code, but what the code does.
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Alfred Lua retweeted
Replying to @booplet_apps
@booplet_apps is pretty nifty for creating small util apps. made an app to convert svg into png, which i often have to do when working on google slides.
Alfred Lua retweeted
It's likely that we'll see a revival of desktop apps thanks to genAI. Vibe coding and running a desktop app for a personal problem is vastly simpler than trying to get a web app to run on a server. You don't need a web app unless you want others to share data and/or collaborate
Alfred Lua retweeted
the reason you feel insane is because all of your "hobbies" are nothing more than glorified consumption. you won't find God in $15k a month of skis, camera gear, or coffee machines. you NEED to create something, just go BUILD, a chair, a bench, carve some wood, anything, please
Alfred Lua retweeted
One of the biggest AI trends I’m excited about is personal apps
Right now, anyone can create an app tailored to their specific needs, all without hiring a developer or designer
As a product design studio founder, should I be worried about this?
Not at all
The more people build things, the more they’ll start to appreciate the craft behind great software
When you’ve tried to do it yourself, you realize how much thought, skill, and care goes into design
It’s like cooking. You might make a decent meal at home, but once you’ve done it yourself, you start to respect what it takes to be a top chef
We need more builders. Not just because they’ll need professionals eventually, but because building creates understanding
And that’s how we all raise the bar for what great software can be
Alfred Lua retweeted
two quotes came together about a decade ago and have become a core flywheel at the foundation of my life
so i wrote about it
becoming the person who does the thing
fredrivett.com/2025/09/10/be…
Alfred Lua retweeted
It's crazy how high my bar has gotten to do evening work stuff. I really hate missing my kids bedtimes.
Alfred Lua retweeted
Early stage startups are best built by pirates and missionaries:
Pirates are looking for an adventure
Missionaries want to do work they can believe in
If you’re either, we’d love to meet you.
(Don’t just take my word for it: LKY thinks you should join a startup too)
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Alfred Lua retweeted
Alfred and SK are always shipping fun and tasteful products. If you want to make an app for your local desktop, give Booplet a spin!
Alfred Lua retweeted
this is very cool (and quite scary as a dev)
in under 10 minutes from download i’d got a decent basic version of @blockshabits working
definitely worth trying booplet if you like to make custom software for your own needs, it’s early but already very powerful
Alfred Lua retweeted
Today, we are launching Booplet (beta)!
Booplet is your personal app library.
Describe what you want, and Booplet will help you create and edit apps. You can then use the apps immediately.
No coding or technical setup required.
Just describe, create, use.
Alfred Lua retweeted
Please go lift weights right now. RIGHT NOW.
Alfred Lua retweeted
Becoming an RL diehard in the past year and thinking about RL for most of my waking hours inadvertently taught me an important lesson about how to live my own life.
One of the big concepts in RL is that you always want to be “on-policy”: instead of mimicking other people’s successful trajectories, you should take your own actions and learn from the reward given by the environment. Obviously imitation learning is useful to bootstrap to nonzero pass rate initially, but once you can take reasonable trajectories, we generally avoid imitation learning because the best way to leverage the model’s own strengths (which are different from humans) is to only learn from its own trajectories. A well-accepted instantiation of this is that RL is a better way to train language models to solve math word problems compared to simple supervised finetuning on human-written chains of thought.
Similarly in life, we first bootstrap ourselves via imitation learning (school), which is very reasonable. But even after I graduated school, I had a habit of studying how other people found success and trying to imitate them. Sometimes it worked, but eventually I realized that I would never surpass the full ability of someone else because they were playing to their strengths which I didn’t have. It could be anything from a researcher doing yolo runs more successfully than me because they built the codebase themselves and I didn’t, or a non-AI example would be a soccer player keeping ball possession by leveraging strength that I didn’t have.
The lesson of doing RL on policy is that beating the teacher requires walking your own path and taking risks and rewards from the environment. For example, two things I enjoy more than the average researcher are (1) reading a lot of data, and (2) doing ablations to understand the effect of individual components in a system. Once when collecting a dataset, I spent a few days reading data and giving each human annotator personalized feedback, and after that the data turned out great and I gained valuable insight into the task I was trying to solve. Earlier this year I spent a month going back and ablating each of the decisions that I previously yolo’ed while working on deep research. It was a sizable amount of time spent, but through those experiments I learned unique lessons about what type of RL works well. Not only was leaning into my own passions more fulfilling, but I now feel like I’m on a path to carving a stronger niche for myself and my research.
In short, imitation is good and you have to do it initially. But once you’re bootstrapped enough, if you want to beat the teacher you must do on-policy RL and play to your own strengths and weaknesses :)
Alfred Lua retweeted
we should all feel an obligation to tell stories about a human future that we actually want to be a part of.
Alfred Lua retweeted
this might be a wild take, but i’m honestly just tired of how new apps gets marketed these days.
launches now feel more like perfume ads than actual product releases.
all this manufactured hype and dramatic trailers that have nothing to do with the actual product, it feels like people are forcing a story to fit their product, instead of letting a real story emerge from actually building something worthwhile.
if you care about what you’re making, let the work speak for itself, real communities form around real value, not just noise.























