Synheart's infrastructure is live. On-device inference is free, forever.
Synheart's infrastructure is live. On-device inference is free, forever.
The Human State Interface
HSI gives your product a real-time read on how someone is doing, focus, stress, recovery, in one consistent format. You build on a clean signal instead of wrangling raw data from every device.
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Four signal domains, one open spec. Every read is worked out on the device and handed to your app as structured JSON, ready to use without extra parsing.
What You Can Build
A single, standard format for human-state data. Whatever the source, a watch, a phone, or both, your app reads the same clean structure: a score, a confidence level, and the moment it applies to. One integration, and you're reading human state the same way everywhere.
HSI is to human-state data what HTTP is to the web, or GPS is to location: a shared layer everything else can build on.
Signal Sources
Three steps, and you only touch the last one:
from a wearable, a phone, or both.
into a structured read. Raw data never leaves the device.
focus, stress, recovery, and more, each with a confidence score.
Human State Domains
Four domains of human state, so you pull exactly what your product needs:
Track focus, stress, and recovery in real time, with data staying on the user's device.
Know when someone is focused or drifting, and build the experience around it.
Give an assistant real context on how someone is doing, not just what they typed.
Collect structured, real-time human-state data for studies and experiments.
HSI reads from devices people own. Connect a wearable for body signals or a digital device for behavioral signals, and integration remains the same.
What You Get
No raw biosignals to clean, no per-device quirks to handle. You get a finished read.
Processing happens on the device, so you build state-aware features without holding sensitive data.
Wearables, phones, and laptops all give you the same HSI read, so one integration covers every device.
Every reading carries a confidence value, so you know when to trust it.
{ "hsi_version": "1.3", "computed_at_utc": "2026-09-16T16:09:54Z", "meta": { "hsi_id": "93704c7a-d96b-5fff-9e81-0ca35e1c04d7", "snapshot_type": "REALTIME", "engine": { "name": "synheart-state-runtime", "version": "0.20.4", "compute_tier": "phone_onnx" } }, "axes": { "cognitive": [ { "name": "focus", "score": 0.45, "confidence": 0.35, "modality": "physiological" }, { "name": "capacity", "score": 0.59, "confidence": 0.46, "modality": "physiological" }, { "name": "mental_fatigue", "score": 0.40, "confidence": 0.07, "modality": "physiological" } ], "affective": [ { "name": "arousal", "score": 0.47, "confidence": 0.98, "modality": "physiological" }, { "name": "stress", "score": 0.14, "confidence": 0.09, "modality": "physiological" }, { "name": "valence", "score": 0.62, "confidence": 0.85, "modality": "physiological" } ], "digital": [ { "name": "focus_quality", "score": 0.82, "confidence": 0.90, "direction": "higher_is_more" }, { "name": "interruption_pressure", "score": 0.21, "confidence": 0.95, "direction": "lower_is_more" } ] }, "privacy": { "contains_pii": false, "consent": "explicit", "purposes": ["self_insight", "adaptive_ux"] }}
For Builders
Openly documented and versioned, so you always know what you're reading. Current version 1.3.
faq
HSI reads from devices people own. Connect a wearable for body signals or a digital device for behavioral signals, and integration remains the same.
Help us build the layer software has been missing.
