> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sandmark.com/llms.txt
> Use this file to discover all available pages before exploring further.

# History window

> How far back you can read is set by your billing plan.

The timeseries endpoints serve a rolling window of history that ends now. Its length depends on how you are
billed:

| Billing plan | History window | Hourly bars per series (approx.) |
| - | - | - |
| Monthly | 1 month | 730 |
| Quarterly | 1 year | 8,760 |
| Annual | 3 years | 26,300 |

The window rolls forward every hour: on a monthly plan, the oldest bar you can read is always about a month
old. Reference data (assets, frequencies and expiries) is not limited by the window.

## How requests are fitted to the window

**start omitted or before the window** `clamped`

Moved forward to the window start. The request succeeds and returns what the window holds.

**end before the window** `403`

Nothing in the range is visible to you, so the request is refused rather than returning an empty series.

```json theme={null}
{
  "statusCode": 403,
  "message": "end is before your data window, which starts at 2026-10-06T22:36:51Z"
}
```

**start and end inside the window** `unchanged`

Served exactly as asked.

## Knowing where the window starts

Every timeseries response carries the window start in a header:

```http theme={null}
Sandmark-Data-Window-Start: 2026-10-06T22:36:47Z
```

Read it when you need to tell a clamped `start` apart from a real gap in the data. If the oldest row you got
back is close to this timestamp, the window cut off your range; if not, the data simply begins later.

> [!TIP]
>
> Need a longer window? Talk to your Sandmark contact about moving to quarterly or annual billing. The
> endpoints and parameters stay exactly the same.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.