> ## Documentation Index
> Fetch the complete documentation index at: https://docs.davidhf.com/llms.txt
> Use this file to discover all available pages before exploring further.
# API reference overview
> Base URL, authentication, shared parameters, and response conventions.
The David API is a REST API that returns JSON. Every endpoint is scoped to a [scenario](/concepts/scenarios) and reads like a conventional market-data API.
Each example shows **cURL** and **Python**. The Python tab uses the [official SDK](/sdk/python) and assumes a configured client: `from david_data import DavidData; dd = DavidData()`.
## Base URL
```text theme={null}
https://api.davidhf.com
```
All requests go to this host over HTTPS.
## Authentication
Send your key in the `X-API-KEY` header on every request. See [Authentication](/authentication).
```bash cURL theme={null}
curl -s "https://api.davidhf.com/scenarios" \
-H "X-API-KEY: your-api-key"
```
```python Python theme={null}
dd.scenarios.list()
```
## The `scenario_id` parameter
Almost every data endpoint requires a `scenario_id` query parameter identifying the world to read from. David generates and curates the scenarios; obtain a `scenario_id` by [listing scenarios](/api-reference/scenarios#list-scenarios).
```bash cURL theme={null}
curl -s "https://api.davidhf.com/prices?scenario_id=&ticker=AAPL" \
-H "X-API-KEY: your-api-key"
```
```python Python theme={null}
dd.prices.get("AAPL", scenario_id="")
```
## Response shape
Responses are JSON objects keyed by the resource name, with the payload as a list or object:
```json theme={null}
{ "prices": [ { "ticker": "AAPL", "close": 183.6, "time": "2026-01-02" } ] }
```
List endpoints return their rows under a named key (`prices`, `news`, `financials`, `companies`, …). Detail endpoints return a single named object.
## Shared query parameters
| Parameter | Type | Description |
| ------------------------- | ------- | -------------------------------------------------------------------------------------- |
| `scenario_id` | string | **Required** on data endpoints. The world to read from. |
| `ticker` | string | Symbol to filter by. Case-insensitive; normalized (e.g. `BRK.B` → `BRK-B`). |
| `limit` | integer | Page size. Each endpoint documents its default and maximum. |
| `offset` | integer | Number of rows to skip, for pagination. |
| `as_of` | date | Point-in-time cutoff (`YYYY-MM-DD`). Returns only data visible on or before this date. |
| `start_date` / `end_date` | date | Inclusive window for time-series endpoints. |
See [Date semantics](/concepts/date-semantics) for how dates and visibility work.
## Pagination
List endpoints page with `limit` and `offset`. To walk a full result set, increase `offset` by `limit` until a short page returns:
```bash cURL theme={null}
curl -s "https://api.davidhf.com/companies?scenario_id=&limit=100&offset=0" \
-H "X-API-KEY: your-api-key"
curl -s "https://api.davidhf.com/companies?scenario_id=&limit=100&offset=100" \
-H "X-API-KEY: your-api-key"
```
```python Python theme={null}
dd.company.list(scenario_id="", limit=100, offset=0)
dd.company.list(scenario_id="", limit=100, offset=100)
```
## Rate limits & errors
Every response carries `X-RateLimit-Limit`, `X-RateLimit-Remaining`, and `X-Account-ID`. See [Errors & rate limits](/errors) for status codes and handling.
## Endpoint groups