Date
GET/v0/date
Validates date strings against multiple common formats. Checks both format correctness and logical validity (e.g., month 1-12, day within month bounds, leap year rules). When valid, returns rich date information including day of week, day of year, ISO week number, quarter, and more.
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Query Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| value | string | Yes | The date string to validate |
| format | string | No | Expected format (e.g., YYYY-MM-DD, DD/MM/YYYY). If omitted, auto-detects. |
Example Request
curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://api.isvalid.dev/v0/date?value=2026-02-19&format=YYYY-MM-DD"
Response Fields
| Field | Type | Description |
|---|---|---|
| valid | boolean | Whether the date string is valid |
| iso | string | The parsed date in ISO 8601 format (YYYY-MM-DD) |
| year | number | Year |
| month | number | Month (1–12) |
| day | number | Day of month |
| dayOfWeek | number | ISO day of week (1 = Monday … 7 = Sunday) |
| dayOfWeekName | string | English name of the day (e.g. Saturday) |
| dayOfYear | number | Day of year (1–366) |
| weekNumber | number | ISO 8601 week number (1–53) |
| weekYear | number | ISO week-numbering year (may differ from calendar year) |
| quarter | number | Quarter (1–4) |
| isLeapYear | boolean | Whether the year is a leap year |
| daysInMonth | number | Number of days in the given month |
Example Response
{
"valid": true,
"iso": "2026-02-19",
"year": 2026,
"month": 2,
"day": 19,
"dayOfWeek": 4,
"dayOfWeekName": "Thursday",
"dayOfYear": 50,
"weekNumber": 8,
"weekYear": 2026,
"quarter": 1,
"isLeapYear": false,
"daysInMonth": 28
}