Elijah Popowitz

21 yo / founder of neptune / prev acq @ 20 / opinionated sports fan

[Elijah Popowitz @ElijahPopowitz]

If you’re moving to SF, Chicago, or NYC, I’m building a platform that makes finding housing simple.

Set your preferences once (budget, neighborhood, etc.) and landlords reach out to you.

Waitlist just opened: https://t.co/NAi7zvz0SQ

[Dan Shipper 📧 @danshipper]

BREAKING:

Anthropic just dropped Claude Fable 5—this is Mythos, made safe for public release. It is the best coding model in the world.

We've been testing it internally @every for the last week or so across coding, writing, marketing, editing, and more—here's our vibe check:

- It broke our benchmarks. Fable scored a 91/100 on our Senior Engineer benchmark—this is human senior engineer level. The previous high score was Opus 4.8 at 63. GPT-5.5 is a 62.

- It's a one-shot wonder. You can set it and forget for hours or overnight on huge coding tasks, and come back to completed work. It cleared entire production bug backlogs, built a playable 3D, and even made a 2-minute animated film—all one-shot.

- Taste and attention to detail. In coding and knowledge work tasks, it has much better taste and attention to detail than we've ever seen. It gets subtle things right, adds little features you might not have thought of, and generally understands the assignment in ways that surprised us.

- Great use of context. We set it loose analyzing customer feedback surveys and our website data and it came back with a crisp, clean report that identified a. our biggest problem and b. a concrete testable solution—and then we sent it off to build that.

- It's best for power users. If you're already used to orchestrating multiple agents in your work, this model can do things that you've never seen before. If you're a knowledge worker or vibe coder with a more basic setup, you're not going to notice a huge difference—in fact, it probably isn't the right model for you.

- It's very slow, token-hungry. Using this thing for regular knowledge work is like squashing an ant with a rocket launcher. It also routinely uses 500k to 1M tokens on tasks. That's why it's best for your heaviest jobs—but not as good for tasks like collaborative writing.
- It's expensive. It's about twice as expensive as Opus, and it's also incredibly token hungry—so expect it to be something you'll use sparingly unless your company pays for it.

Overall, I think of it like a warp drive for coding: It can get you across the galaxy in a few hours, when it used to take months or years. But it's not appropriate for getting around town—you need something faster, cheaper, and more maneuverable.

The ceiling is extraordinarily high on this model though. Even our most advanced testers like @kieranklaassen felt like they were only scratching the surface of it.

Want our full vibe check with all of our testing and benchmarks? Read it on @every: https://t.co/MgJLZszJUB

[Elijah Popowitz @ElijahPopowitz]

@sohammehra_ @karpathy @dwarkeshpodcast This guys seems smart

[Soham Mehra @sohammehra_]

@karpathy highlighted the benefit of a personal tutor during his appearance on the @dwarkeshpodcast podcast perfectly:

The ability to figure out exactly where their pupil's skill level is and challenge them just enough to push their understanding further.

I love teaching and eventually want to open a brick and mortar school myself post @morphlabs_ai days. Until then, the goal is to figure out how to deliver that personal tutor relationship at scale.

I'm starting a new ongoing project to try and replicate that experience. It's called microtutor, with the intention of helping anyone gain a deep understanding of topics they desire. Constantly tracking your mastery and evaluating your understanding of topics.

I'm releasing the first version here. It's a cli application, still rough around the edges, but I'm looking forward to having people try out the experience.

https://t.co/RF2HknlFVg

If you try it, tell me what's broken and what could be better. That's the only way this kind of education will get better.

[Sean @seanrobins_]

It took liking every Jewish girl on Hinge and inviting them to a party to get a solid ratio in SF @OyBay

[Elijah Popowitz @ElijahPopowitz]

@seanrobins_ Can't wait

[Elijah Popowitz @ElijahPopowitz]

How Stafford felt on that 4th&1

[Elijah Popowitz @ElijahPopowitz]

What a game

[Elijah Popowitz @ElijahPopowitz]

This game is the Super Bowl

[Elijah Popowitz @ElijahPopowitz]

Davante!!!

[Elijah Popowitz @ElijahPopowitz]

Rams special teams is a new level of terrible

[Elijah Popowitz @ElijahPopowitz]

Fuck a 9-9-6

[Elijah Popowitz @ElijahPopowitz]

Today I started building in public

[Elijah Popowitz @ElijahPopowitz]

Founders, what are your personal goals for 2026?

[Elijah Popowitz @ElijahPopowitz]

@stugotz790 And more talent*

[Elijah Popowitz @ElijahPopowitz]

@1Umairshaikh Pushing first product to the public 🤞

[Elijah Popowitz @ElijahPopowitz]

The NFL script writers cooked today

[Elijah Popowitz @ElijahPopowitz]

That 3 & 17 broke my heart

[Elijah Popowitz @ElijahPopowitz]

Has AI gotten worse at writing?

[Elijah Popowitz @ElijahPopowitz]

@NWischoff Building a new type of marketplace

[Elijah Popowitz @ElijahPopowitz]

@FounderKyle LinkedIn over the summer was v effective for outreach. Now it kind of sucks