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Health API

2 endpoints for health workflows. Every call requires bearer authentication and uses the standard ToolsOnDuty response envelope.

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EndpointAPI key

lastMenstrualPeriod *cycleLength

POST/v1/health/due-date1 credit / call

Pregnancy due-date estimate

Estimate due date and trimester milestones from the last menstrual period and cycle length.

Parameter	Type	Required	Description
lastMenstrualPeriod	string	Yes	First day of the last menstrual period, YYYY-MM-DD.
cycleLength	number	No	Typical cycle length in days. Default: 28.

Request

curl -X POST https://toolsonduty.com/api/v1/health/due-date \
  -H "Authorization: ******" \
  -H "Content-Type: application/json" \
  -d '{"lastMenstrualPeriod":"2026-01-01","cycleLength":28}'

Response

{
  "ok": true,
  "data": {
    "estimatedDueDate": "2026-10-08"
  }
}

POST/v1/health/ovulation1 credit / call

Ovulation calculator

Estimate ovulation, fertile-window and next-period dates from the first day of the last period and average cycle length.

Parameter	Type	Required	Description
lastPeriodDate	string	Yes	First day of the last period in YYYY-MM-DD format.
cycleLength	number	No	Average cycle length in days (21-45). Default: 28.

Request

curl -X POST https://toolsonduty.com/api/v1/health/ovulation \
  -H "Authorization: ******" \
  -H "Content-Type: application/json" \
  -d '{"lastPeriodDate":"2026-10-01","cycleLength":28}'

Response

{
  "ok": true,
  "data": {
    "ovulationDate": "2026-10-15",
    "fertileWindowStart": "2026-10-10"
  }
}