<!-- https://developers.silktide.com/v1/analytics/audience/get-browser-sizes-over-time | Analytics / Audience -->

# Get visitors at each browser size, step by step over a period

`GET /v1/results/analytics/browser-sizes-over-time`

Returns one series per browser size, with the visitors at that size in each step of a period, for an analytics view or a website. The sizes are the same as [Get browser sizes](https://developers.silktide.com/v1/analytics/audience/get-browser-sizes.md): three by default, seven with `simple` set to `false`.

Each step counts the visitors at the size in that step. `total` adds the steps up, so a visitor seen on two days counts twice: it is not the number of people who used the size. A step with no visitors at a size has no `breakpoint`; read it from another step.

Send a `period`. With the default, `all`, this answers with an error. How long each step is, and how to choose it, is under [Over time](https://developers.silktide.com/v1/analytics/audience.md). This query does not take `previousPeriod`.

The old documentation gave this query's path as `/v1/results/analytics/browser-sizes`, which is [Get browser sizes](https://developers.silktide.com/v1/analytics/audience/get-browser-sizes.md). This one is `/v1/results/analytics/browser-sizes-over-time`.

## Request

### Query parameters

- `view` (string, optional, matches `^(all|[1-9]\d*)$`): The analytics view to read: its id, the number after `/analytics/` in its address in Silktide, or `all` for all of the account's analytics. Send this or `websiteId`.
- `websiteId` (integer, optional, at least 1): Instead of `view`, a website whose analytics to read. The website must have Analytics set up.
- `sectionId` (integer, optional): With `websiteId`, a section of the website. Defaults to `0`, the whole website.
- `period` (string, optional): The date range. Defaults to `all`. The spaced forms (`-7 days`, `month to date`) are older names that keep working. `custom` needs `from` and `to`. One of: `all`, `today`, `last-7-days`, `last-30-days`, `last-90-days`, `month-to-date`, `last-month`, `year-to-date`, `last-12-months`, `custom`, `-7 days`, `-30 days`, `-90 days`, `-1 month`, `month to date`, `year to date`, `-12 months`.
- `from` (string, optional): With `period=custom`, the first day, such as `2026-10-01`.
- `to` (string, optional): With `period=custom`, the last day.
- `timezone` (string, optional): The IANA time zone days are read in, such as `America/New_York`. Defaults to `UTC`.
- `filters` (map of strings, optional): Only visits matching every filter, keyed by what is filtered: `filters[url]=contains:/blog`. Each value is `{operator}:{value}`, with operator `is`, `not`, `contains`, `starts`, `gt` or `lt`. Keys include `url`, `hostName`, `entryUrl`, `exitUrl`, `event`, `outgoingUrl`, `referrer`, `source`, `medium`, `campaign`, `content`, `term`, `countryCode`, `regionCode`, `language`, `deviceType` (`desktop`, `tablet` or `mobile`), `operatingSystem` and `browser`.
- `interval` (string, optional): With `period=custom`, the length of each step: an hour, a day, a week starting on Monday, a month or a year. Ignored with any other period. Left out, steps are hours for a single day, months for exactly twelve months, and days otherwise. One of: `PT1H`, `P1D`, `P7D`, `P1M`, `P1Y`.
- `simple` (boolean, optional): `false` for seven finer sizes, from `Mobile (small)` to `Desktop (large)`, instead of `Mobile`, `Tablet` and `Desktop`. Defaults to `true`. In a query string, send `0` or `false`.

## Response

Status `200`.

- `result` (object, required): The answer.
  - `multiSeries` (list of objects, required): One series per size anything was recorded at, the largest `total` first. Empty when nothing was recorded.
    - `label` (string, required): The size: `Mobile`, `Tablet` or `Desktop`, or with `simple` false, `Mobile (small)`, `Mobile (medium)`, `Mobile (large)`, `Tablet`, `Desktop (small)`, `Desktop (medium)` or `Desktop (large)`.
    - `key` (string, required): The size again, the same as `label`.
    - `total` (integer, required): The size's steps added up: visitors seen in more than one step count once per step.
    - `series` (list of objects, required): One step per hour, day, week or month of the period, oldest first. A step with no visitors at the size reads `0`.
      - `time` (string, required, matches `^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$`): When the step starts, as `YYYY-MM-DD HH:MM:SS` in the request's `timezone`.
      - `visitors` (integer, required): Visitors at the size in the step.
      - `breakpoint` (integer, optional, at least 1): The widest browser window the size covers, in CSS pixels. Absent on a step with no visitors at the size.
  - `range` (object, required): The dates the series covers.
    - `start` (string, required, matches `^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$`): When the first step starts, as `YYYY-MM-DD HH:MM:SS` in the request's `timezone`.
    - `end` (string, required, matches `^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$`): When the range ends, as `YYYY-MM-DD HH:MM:SS`: midnight after its last day, so the range runs up to but not including it.
- `selector` (string, required): The query that answered, as its path: `/v1/results/scores`.
- `duration` (number, required): Seconds Silktide took to answer.

## Errors

| Status | Type | When |
| --- | --- | --- |
| 404 | `ModelNotFound` | No view or website with that id exists in the account, or the API key's user cannot see it. |
| 403 | `AccessDenied` | The API key's user cannot read that analytics view. |
| 200 | `ModelNotFound` | The website has no Analytics set up. The body is an error despite the status. |
| 200 | `InvalidRequest` | Neither `view` nor `websiteId` was sent. The error's own `status` is `400` and `properties.field` is `view`. The body is an error despite the status. |
| 200 | `InvalidArgument` | A filter names a key or operator Analytics does not know. The body is an error despite the status. |
| 200 | `Error` | `period` is `all` or left out, which means `all`. Over-time queries need a period with a start. The body is an error despite the status. |
| 200 | `InvalidArgument` | `period` is not one of its values, or is `custom` without both `from` and `to`. The body is an error despite the status. |
| 200 | `Unspecified` | `interval` is not one of its values. The body is an error despite the status. |
| 401 | `NotLoggedIn` | No API key was sent, or it is not a key for this region. |
| 429 | `TooManyRequests` | Too many requests to this path in five seconds. Retry after the number of seconds in the `Retry-After` header, which `properties.retryAfter` repeats. |
| 503 | - | Silktide is busy. Retry after the number of seconds in the `Retry-After` header. |

## Access

- Permission: View analytics view (View all analytics for `view=all`)
- Plan feature: none
- Edition: Silktide 4 and Silktide 5
- Cost: free
- Stability: stable, since 1.0.0

## Example: Mobile, desktop and tablet visitors each day

```bash
curl "https://api.eu.silktide.com/v1/results/analytics/browser-sizes-over-time?view=all&period=custom&from=2026-10-01&to=2026-10-02" \
  -H "Authorization: silktide token=$SILKTIDE_API_KEY"
```

Response:

```json
{
  "result": {
    "multiSeries": [
      {
        "label": "Mobile",
        "key": "Mobile",
        "total": 126,
        "series": [
          {
            "breakpoint": 425,
            "visitors": 65,
            "time": "2026-10-01 00:00:00"
          },
          {
            "breakpoint": 425,
            "visitors": 61,
            "time": "2026-10-02 00:00:00"
          }
        ]
      },
      {
        "label": "Desktop",
        "key": "Desktop",
        "total": 90,
        "series": [
          {
            "breakpoint": 1440,
            "visitors": 38,
            "time": "2026-10-01 00:00:00"
          },
          {
            "breakpoint": 1440,
            "visitors": 52,
            "time": "2026-10-02 00:00:00"
          }
        ]
      },
      {
        "label": "Tablet",
        "key": "Tablet",
        "total": 15,
        "series": [
          {
            "breakpoint": 1024,
            "visitors": 15,
            "time": "2026-10-01 00:00:00"
          },
          {
            "time": "2026-10-02 00:00:00",
            "visitors": 0
          }
        ]
      }
    ],
    "range": {
      "start": "2026-10-01 00:00:00",
      "end": "2026-10-03 00:00:00"
    }
  },
  "selector": "/v1/results/analytics/browser-sizes-over-time",
  "duration": 0.02
}
```