Track weekly active users from Amplitude with a Monday report

SKILL.md---
name: amplitude-weekly-active-users
description: "Every Monday: last week's active users from Amplitude, the change on the week before, new and returning users, and a 12-week trend. Use when the user asks for this, or when it runs on a schedule."
---

# Amplitude weekly active users

Every Monday: last week's active users from Amplitude, the change on the week before, new and returning users, and a 12-week trend.

Weekly active users is the number founders quote and product managers watch, and in Amplitude it lives in a chart someone has to open, set to weekly, and read off. When it dips, the next question is whether new users or returning ones explain it.

Every Monday the agent pulls 12 weeks of weekly active and new users from Amplitude, splits last week by platform, and posts the tile. The card says how much of the change came from new users, so a dip from a slow acquisition week reads differently from a dip in retention.

## Two ways to get the data

Use the API or MCP route when you have an MCP server, a CLI or an API token for the app. Otherwise, if you can drive a browser the user is signed in to (Claude in Chrome, a Playwright or Chrome DevTools MCP server), use the browser route. Say which one you used.

## Route A: API or MCP server

### What you need

- The project's API key and secret key (Organization settings > Projects) in `AMPLITUDE_API_KEY` and `AMPLITUDE_SECRET_KEY`, or Amplitude's MCP server (OAuth), which answers the same chart queries.

If something is missing, say what and stop; do not invent numbers.

### Steps

1. **Pull weekly active users** (Amplitude): Call `GET https://amplitude.com/api/2/users?start=<12 weeks ago, YYYYMMDD>&end=<last Sunday>&m=active&i=7` with basic auth (API key and secret key). `data.series[0]` holds one value per week, labeled in `xValues`. EU projects use `https://analytics.eu.amplitude.com`.
2. **Pull new users** (Amplitude): Make the same call with `m=new`. Returning users for the week are active minus new.
3. **Split last week by platform** (Amplitude): Call it once more with `m=active&i=7` and `g=platform` for the last two weeks, and keep each platform's count and change.
4. **Post the tile**: Drop the week still in progress. Weekly active users is the headline with 12 weeks of history; new and returning users go in the glance and the platform split in the opened card, with one line on what drove the change.

## Route B: the browser

### What you need

- Signed in to Amplitude with a Member or Admin role on the project; Viewers can open charts but not always create new ones, so open a saved weekly active users chart instead if you are a Viewer.

If something is missing, say what and stop; do not invent numbers.

### Steps

Start at https://app.amplitude.com/. The user is signed in already; never type passwords or codes, and ask if a sign-in page appears.

1. **Open the project and a new segmentation chart**: Sign-in lands on your organization. Pick the project in the project switcher at the top left, then choose **Create > Chart > Segmentation** (the Event Segmentation chart).
2. **Set the event and the interval**: For the event pick `Any Active Event`, measured as **Uniques**. Set the interval to **Weekly** and the date range to a custom range from 12 full weeks ago to last Sunday, so the week in progress stays out.
3. **Read 12 weeks of active users**: Switch the chart to the **Data table** view under it and read one number per week. The last two columns give last week and the week before; the change between them is the headline.
4. **Read new users**: Change the event to `New User` (the `[Amplitude] New User` event) with the same settings, and read last week and the week before. Returning users are active minus new for each week.
5. **Split last week by platform**: Back on the active-users chart, add **Group by** on the user property `Platform`. Read last week and the week before for Web, iOS and Android, and work out each change.

Note: Amplitude charts count the current week up to today, so set the end date to last Sunday rather than using Last 12 weeks. Platforms overlap: a person active on web and iOS counts once in the total and once per platform.

## The report

- **Weekly active users** last week, the change on the week before, and a 12-week trend.
- **New** and **returning** users, each with its change.
- **By platform**: web, iOS and Android, with their change.
- One line on what drove the week.

## Post it to Briefkin

When `BRIEFKIN_TOKEN` is set, or `~/.config/briefkin/env` exists (the installer from https://briefkin.dev/docs writes it), also send the result to the user's Briefkin board as one card. Keep the `item_key` the same on every run so the card updates in place, use a new `event_id` per run, and put today's real numbers in place of the example ones. If the request fails, say so once and carry on.

```bash
[ -n "${BRIEFKIN_TOKEN:-}" ] || . ~/.config/briefkin/env
curl -sS -X POST "${BRIEFKIN_URL:-https://briefkin.dev}/v1/events" \
  -H "authorization: Bearer $BRIEFKIN_TOKEN" \
  -H "content-type: application/json" \
  -d @- <<'JSON'
{
  "v": 1,
  "event_id": "amplitude-weekly-active-users/<date of this run, e.g. 2026-10-16>",
  "item_key": "amplitude-weekly-active-users",
  "project": "Acme",
  "source": "Amplitude weekly active users skill",
  "kind": "metric",
  "title": "Weekly active users up 4.2%",
  "metric": {
    "label": "Weekly active users",
    "value": 18640,
    "better": "higher",
    "period_start": "<start of the period, ISO 8601>",
    "period_end": "<end of the period, ISO 8601>"
  },
  "glance": [
    {
      "type": "Grid",
      "props": {
        "columns": 2
      },
      "children": [
        {
          "type": "Stat",
          "props": {
            "label": "New users",
            "value": 3120,
            "delta": 9
          }
        },
        {
          "type": "Stat",
          "props": {
            "label": "Returning users",
            "value": 15520,
            "delta": 3
          }
        }
      ]
    },
    {
      "type": "Badges",
      "props": {
        "items": [
          {
            "label": "Web 9,870"
          },
          {
            "label": "iOS 5,410",
            "tone": "ok"
          },
          {
            "label": "Android 3,360"
          }
        ]
      }
    }
  ],
  "widget": [
    {
      "type": "Table",
      "props": {
        "columns": [
          "Platform",
          "Active users",
          "Change"
        ],
        "align": [
          "left",
          "right",
          "right"
        ],
        "rows": [
          [
            "Web",
            9870,
            "+2%"
          ],
          [
            "iOS",
            5410,
            "+7%"
          ],
          [
            "Android",
            3360,
            "+6%"
          ]
        ]
      }
    },
    {
      "type": "Callout",
      "props": {
        "text": "New users rose 9% and returning users 3%. iOS grew fastest, in the first full week after the 4.12 release.",
        "tone": "info"
      }
    }
  ],
  "size": "md"
}
JSON
```

Widgets come from the Briefkin catalog (https://briefkin.dev/v1/catalog). Without a token, just give the user the report.

Set `period_start` and `period_end` to the window the number covers: the tile names it from them ("Last 7 days", "Today", "This month"). For a count right now (open items, a balance), send `"period_label": ""` so no period shows; for another name, send it as `period_label` (at most 24 characters).

## Run it on a schedule

Suggested: Mondays at 8:00 (`0 8 * * 1`). From cron, with the agent signed in on that machine:

```bash
0 8 * * 1 claude -p "Run the amplitude-weekly-active-users skill"
# Codex: codex exec, Gemini CLI: gemini -p, Copilot CLI: copilot -p, OpenCode: opencode run
```

Or use the agent's own scheduler (Claude Code routines, Codex automations, Claude or ChatGPT scheduled tasks): https://briefkin.dev/skills/amplitude-weekly-active-users#schedule

Source: https://briefkin.dev/skills/amplitude-weekly-active-users