Eli Rousso

Design & Technology
New York City

Background

Over twenty years making software. I’ve founded and run venture-backed and self-funded businesses across consumer hardware, AI, crypto, and developer infrastructure. I’ve led small teams and designed, built, and operated products solo.

Software

Slate is a private journal that stays on your device. Designed, built, and operated solo.

Slate’s recording, journal entries, reflections, and weekly review screens on four iPhones.
  • Reached 13,000+ downloads across 118 countries within the first 46 days of launch.‡
  • Grew to 750+ paying customers across 82 countries.‡
  • Converted approximately 31% of completed free trials into paying customers.‡

Rams provides design and accessibility review for developers, built into the way they ship.

Rams homepage showing its design review tool and an example code review.
  • Delivered 7,700+ design and accessibility reviews across 4,000 repositories.‡
  • Weekly review volume grew roughly fourfold in a month, without paid acquisition.‡
  • Flagged 26,000+ interface issues, from inconsistent spacing to inaccessible contrast.‡

Studio

HSLA0001 is my independent studio behind Slate, Rams, and my other software.

  • Build and operate a portfolio spanning consumer apps, developer tools, subscriptions, and one-time purchases.
  • Created Framework: four focused apps for writing, focus, and habits, each built around a single daily practice.
  • Shipped Autobahn, an open-source kanban board that turns markdown files into a working project board.

Startups

Multi offered self-custody Bitcoin without the fear. Founded it and ran it as CEO, 2021 to 2024.

  • Split keys across your own devices with multi-party computation, so no single phone, laptop, or piece of paper could lose the vault.
  • I raised the funding myself from leading investors and built a world-class team across industrial design, electrical engineering, and software.
  • I set the concept, designed the software that shipped, and led design and engineering on the hardware, a steel key you tapped to recover a vault or to pay.

Design

I was a Product Design Principal at Cash App from 2017 to 2021, where I led the vision and the architecture for v3 and v4, set the bar for design quality across the product, and put the design principles, critiques, and reviews in place.

I’ve also worked with teams at Square, Shopify, Squarespace, Whatnot, Faire, Compass, Oscar, Mirror, Huge, and Gin Lane.

Services

A Session is one decision, worked through together. Bring your app, prototype, or idea, and leave with a clear next step. 60 minutes, $3,000.

  • What to ship, where purchases break down, or what deserves another month.
  • A working conversation. No report, no implementation, no follow-up.
  • Pay upfront to confirm. Full refund with 24 hours’ notice.
Book a session

A Prototype is one thing, finished: a brand, a web product, or an iOS app you can put in front of investors or customers. Two weeks, $80,000.

  • Delivered as code, so what you get runs rather than a deck describing what it would do.
  • You see it each Friday, and everything is yours at the end.
  • Scoped to what can ship in fourteen days.
Start a prototype

Advisory is my eyes on everything before it ships: product, brand, hiring, and the pitch. $25,000 a month, plus equity.

  • One call a week, plus whatever comes up in between.
  • Principal judgment without adding a principal hire.
  • Three-month minimum.
Ask about advisory