When we first launched Whisp, all processing happened in the cloud. It was the pragmatic choice—cloud infrastructure gave us access to powerful GPUs and allowed us to iterate quickly on our models. But we always knew that for some users, sending voice data to servers wasn't an option.
The Privacy Imperative
Healthcare professionals dictating patient notes. Lawyers discussing confidential cases. Executives strategizing sensitive business decisions. For these users, even the most secure cloud infrastructure isn't enough. They need their voice to never leave their device.
We heard this feedback loud and clear from our early enterprise customers. So we set ourselves an ambitious goal: build an on-device processing system that matches our cloud accuracy.
The Technical Challenge
Modern speech recognition models are massive. Our cloud models run on clusters of high-end GPUs with hundreds of gigabytes of memory. Running these on a laptop seemed impossible at first.
The breakthrough came from three innovations:
- Model distillation: We trained smaller "student" models to mimic our large "teacher" models, capturing 95% of the accuracy at 10% of the size.
- Quantization: We reduced numerical precision from 32-bit to 8-bit, cutting memory requirements by 75% with minimal accuracy loss.
- Neural engine optimization: We rewrote our inference engine to take full advantage of Apple's Neural Engine and similar hardware accelerators on other platforms.
The Results
After 18 months of R&D, we achieved something remarkable: our on-device model matches cloud accuracy for English dictation while running entirely on your local hardware. No internet connection required. No data ever leaves your machine.
On an M1 MacBook, the on-device engine processes speech in real-time with less than 100ms latency. Battery impact is minimal—you can dictate for hours without significant drain.
Privacy Mode: How It Works
Enabling Privacy Mode is simple: just flip a switch in settings. Once enabled, all speech processing happens locally. Your audio is processed, transcribed, and immediately discarded. We don't log it, store it, or send it anywhere.
For organizations that require it, we provide cryptographic attestation that no network calls are made during dictation. Your compliance team can verify our privacy claims independently.
Looking Forward
Privacy Mode is just the beginning of our on-device journey. We're working on bringing AI Auto Edits to local processing, which requires even more sophisticated optimization techniques. We're also expanding language support, with German and Spanish coming to Privacy Mode later this year.
The future of voice AI isn't just about accuracy—it's about trust. And trust starts with giving users complete control over their data.