---
title: "Retention cohorts, or the reason there are none"
method: GET
path: "/api/retention"
tags: ["analytics"]
---

# Retention cohorts, or the reason there are none

`GET /api/retention`

## Request

- Base URL: `https://app.vitrus.dev/app`
- URL: `https://app.vitrus.dev/app/api/retention`
- Auth: one of:
  - API key in cookie `vitrus_session`
  - HTTP bearer

Returns `available: false` with a message and a remedy when the site has no identified users. The visitor id is salted per day, so cross-day retention of anonymous traffic is arithmetically impossible rather than merely disallowed. Call vitrus.identify() to make it computable.

## Query parameters

- `site` string, required
- `days` integer

## Response `200`

Cohort matrix, or the reason it cannot be computed.

---

[API](https://skmtc.dev/vitrus/apis/vitrus-api.md) · [All operations](https://skmtc.dev/vitrus/apis/vitrus-api/llms.txt) · [OpenAPI document](https://skmtc.dev/vitrus/apis/vitrus-api/revisions/a7d8c6e18f7c?raw)