The hum of the server room was a low thrum, a constant companion to Eric Migicovsky as he finalized the Index 01’s software. It was late December 2025, and the air in Core Devices’ small office hummed with a different kind of energy: the quiet anticipation of a product launch. After the acquisition of Pebble by Fitbit and the subsequent open-sourcing of PebbleOS, Migicovsky, the original founder, was back, aiming to carve out a new niche in the wearable market. This time, he wasn’t after the wrist; he was after the finger.
The Index 01, a $75 smart ring, isn’t designed to compete with the always-on, always-listening AI assistants. Instead, it offers a simple, elegant solution: a press of a button to record quick notes and reminders. The ring itself is made of stainless steel, water-resistant to one meter, and designed to be worn constantly. Migicovsky, having worn a prototype for three months, believes it solves a persistent problem: the fleeting nature of ideas. “I get ideas or I remember something, and if I don’t write it down that second, I forget it,” he told TechCrunch.
The AI component is handled by open-source speech-to-text models running locally on the user’s smartphone, via the Pebble mobile app. This design choice prioritizes privacy; all recordings are stored on the user’s device, not in the cloud. The battery, Migicovsky claims, will last for years, offering approximately 12 to 14 hours of recording time. Considering the average user records 10-20 short notes a day, the battery should last about two years, according to the founder. When the battery dies, users can send the ring back to the company for recycling.
The ring’s functionality extends beyond simple note-taking. It supports 99+ languages and can sync with calendar apps like Notion. The open-source nature of the software also allows for community-driven customization. The button is programmable, allowing users to control music, trigger the phone’s camera, or even send messages via apps like Beeper.
The path to the Index 01 hasn’t been without its lessons. Migicovsky acknowledges the challenges of hardware, as his experience with Pebble demonstrated. “I didn’t earn any money during Pebble — we exited, but it was not a great exit,” he admitted. Core Devices, a small team of five, is taking a different approach, self-funded and focused on sustainability. The company is starting from profitability, a marked contrast to the venture-backed startup model.
The Index 01 is currently available for pre-order, with the offer ending in March 2026, after which the price increases to $99. It’s available in silver, polished gold, and matte black, and works with both iOS and Android devices. For Migicovsky and Core Devices, it’s a bet on a different path, one where a simple, well-designed product can solve a specific problem, and maybe, just maybe, make a dent in the crowded world of wearable tech.
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