Cactus Whistle: speech recognition in a 16.9 MB file

Cactus Compute has released Whistle, an open speech-to-text model that is a single 16.9 MB file and runs on an ordinary CPU. It handles up to 30 seconds of audio at a time in English, German, French, Spanish, Italian, Dutch and Polish.

It ships inside Cactus's on-device runtime, Needle, with weights on Hugging Face. The company claims it "mostly beats Whisper base" while being about 8.6 times smaller and 6.6 times faster to the first word. Those are Cactus's own comparisons.

One detail stands out: on silence or background noise it returns an empty transcript, rather than inventing a sentence.

Why it matters

Speech recognition this small can run on wearables, microcontrollers and in cars with no trip to a server. The refusal to hallucinate on silence is a quiet but important reliability feature for anyone building voice systems.