# Of the visitors first seen in a week or month

> tidekeeper's API reference: https://tidekeeper.eu/docs/api/get-sites-site-retention

`GET /api/v1/sites/{site}/retention`

Of the visitors first seen in a week or month, the share who came back.

## Parameters

- `site` (in path, needed): A site's id or name
- `grain` (in query): week or month
- `what` (in query): visit, or goal:<name>

## The answer

200, `RetentionReport`

- `back_first` (number or null): Back in the first period after the one they were first seen in: the mean over the cohorts old enough to say, and how many those are.
- `back_first_cohorts` (integer, needed)
- `back_fourth` (number or null): Still coming in the fourth period.
- `back_fourth_cohorts` (integer, needed)
- `by_source` (list of RetentionSplit, needed)
- `cohorts` (list of CohortRow, needed)
- `coverage` (Coverage, needed)
- `days_to_return` (number or null): Median days until a visitor's second day.
- `grain` (string, needed): `week` or `month`.
- `site` (string, needed)
- `what` (string, needed): `visit`, or a goal's name.

## Asking

```sh
curl https://tidekeeper.eu/api/v1/sites/example.org/retention \
    -H "Authorization: Bearer $TIDEKEEPER_TOKEN"
```