Sessionwire

Sessionwire is a virtual studio for remote recording and mixing, with over 36,000 accounts. It has hosted more than 100,000 calls since 2023. I've led development since 2017 and designed the current architecture.

What I work on

Architecture: The same web app runs in the browser and inside the macOS and Windows apps. In 2022 I replaced the call provider, which raised the limit from about five people a call to hundreds.
Mixer: Each person in a call gets a channel strip: a gain fader, a mute that keeps the fader level, and stereo meters before and after the fader. Talkback and program audio go to separate outputs, so talkback can stay in headphones while the mix plays on monitors.
Search: Three searches: find people by describing them, find audio by describing it, or drop in a track to find audio that sounds like it. It uses Voyage, CLAP and MERT embeddings and costs under $30 a month to run.
Calls: Audio and video run on Daily. In the largest call, 216 people joined and 169 were connected at once. The server keeps a record of every call, so a dropped connection rejoins on its own. Calls of about 100 people used to lock the servers at 100% CPU. They now peak at 20–30%.
Tests: About 2,000 automated tests run before every deploy. About 300 are end-to-end, including multi-person calls.
Process: I build with coding agents. Large changes are reviewed by a second model family, then by me. From 2021 to 2025 I also directed a second developer's work and reviewed every pull request.
Other: I also look after payments, the public API, encrypted peer-to-peer file transfer and signing the desktop apps in CI.