Spren HRV API is RESTful and partially async. It communicates with JSON request and response bodies. Authorization is in the header.
Environments
https://test.api.spren.com
https://prod.api.spren.com
Headers/Authorization
Header
Notes
Example
X-API-KEY
Your API key for authorization
X-API-KEY: <API key>
Content-Type
JSON, if request body present
Content-Type: application/json
Endpoints
POST/submit/sdkData
POST/submit/deviceData
GET/results/{guid}
GET/populationComparison
POST/submit/userData

Biomarkers and Insights
readiness and ansBalance require 2 readings on 2 separate days within 10 days or value will be null
This will occur for a user's first reading OR after their first reading if they have not performed a reading in the last 10 days, and when this occurs an errorDescription of "baseline not set" is returned. See GET /results/{guid} below for more details.
Response Key
Description
Type
Data Type
Return Values
hr
Heart rate
Biomarker
number
Floating point, unrestricted range
hrvScore
HRV score
Biomarker
number
Floating point, 0-100
rmssd
RMSSD
Biomarker
number
Floating point, unrestricted range
breathingRate
Breathing/respiration rate
Biomarker
number
Floating point, unrestricted range
readiness*
Morning readiness
Insight
number
Int, 0-10
ansBalance*
ANS balance level
Insight
number
Int, 1-5
balance*
ANS balance
Insight
string
SNS | PSNS
signalQuality
Signal quality
Other
number
Int, 1-3
*require 2 readings on 2 separate days within 10 days or value will be null for insights
Endpoints - Async
From a Spren Vision SDK reading
POST
Request
Header Parameters
X-API-KEY
String
required
Your API key
Content-Type
String
required
"application/json"
Body Parameters
user
String
required
User ID
readingData
String
required
Spren Vision SDK reading data

While we accept interbeat intervals (IBIs) from any device, the following devices have been tested
Apple Watch
Polar H7, H9, and H10
Garmin HRM Dual and HRM Pro
Suunto Smart Belt
4iiii Viiiiva
Zephyr HxM
Cardiosport TP3
Ambiotex smart shirt with cardio-monitor
BlueLeza HRM Blue
From an external measurement device
POST
Request
Header Parameters
X-API-KEY
String
required
Your API key
Content-Type
String
required
"application/json"
Body Parameters
user
String
required
User ID
readingData
Object
required
See Request Body Example and Request Body Schema tabs

For certain insights, a minimum number of readings are required. See the Biomarkers/Insights section.
Status/Value
For each biomarker or insight, a status/value JSON object is returned
Status/Value
1{
2 "status": <string, "pending", "complete", or "error">
3 "value": <string, number, optional, null on error, see Biomarkers/Insights section below for precision and range>,
4 "errorDescription": <string, optional>
5}

State Permutations
status
Description
value (for calculated Biomarker/Insight)
errorDescription
pending
Calculation is in progress
null
null
complete
Calculation is complete
string, number, see Biomarkers/Insights section below for precision and range
null
error
Calculation has errored
null
string, error encountered
With a GUID from a SDK or device data endpoint POST response
1{2"message":"Authentication/Authorization error; please check that your authorization information is correct."3}
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Some screen readers may require you to be in focus mode or to use your pass through key
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When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key
Press space bar to start a drag.
When dragging you can use the arrow keys to move the item around and escape to cancel.
Some screen readers may require you to be in focus mode or to use your pass through key