Subtl

Doing business across borders means taking calls in a language you only half control. Existing tools either transcribe after the fact, which is useless while you are speaking, or live inside one meeting platform, which is useless when the client picks a different one.

Subtl captures the other side’s audio from the system output and your own microphone on the device, then draws a translucent overlay above whatever application the call is happening in — Zoom, Meet, Teams, Telegram, WhatsApp or FaceTime. The overlay shows the original text, its translation, and a suggested answer drawn from documents you loaded before the call, so a pricing question gets answered with your pricing rather than a guess.

It is a desktop application rather than a browser extension precisely because the capture has to work regardless of where the call is. The engineering underneath is unusual for a product this small: a Rust client core for segmentation and streaming, a Swift library for macOS system-audio capture, and a Go realtime gateway handling speech recognition, translation and suggestion in one pass.