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# Linking Open Exchange Rates as a source

Canonical URL: https://posthog.com/docs/data-pipelines/sources/open-exchange-rates

> **Cloud region:** This page uses US Cloud hosts. For an EU Cloud project, use `https://eu.posthog.com` instead of `https://us.posthog.com` or `https://app.posthog.com` (app host for links).

## On this page

- [Prerequisites](#prerequisites)
- [Adding a data source](#adding-a-data-source)
- [Sync modes](#sync-modes)
- [Configuration](#configuration)
- [Supported tables](#supported-tables)
- [Troubleshooting](#troubleshooting)

![](https://res.cloudinary.com/dmukukwp6/image/upload/texture_tan_9608fcca70)

![](https://res.cloudinary.com/dmukukwp6/image/upload/texture_tan_dark_a92b0e022d)

Let AI connect your sources for you

Skip the manual setup — run this in your project and the wizard auto-detects your databases and APIs and connects them to PostHog.

`npx @posthog/wizard warehouse`

![PostHog Wizard hedgehog](https://res.cloudinary.com/dmukukwp6/image/upload/wizard_3f8bb7a240.png)

![](https://res.cloudinary.com/dmukukwp6/image/upload/wizard_3f8bb7a240.png)Let AI connect your sources for you

The Open Exchange Rates connector syncs currencies, latest, historical, and more into the PostHog data warehouse, so you can analyze them alongside your product data.

## Prerequisites

Credentials that can read the data you want to sync. PostHog only reads data, so read access is enough.

## Adding a data source

1.  In PostHog, go to the [Sources tab](https://app.posthog.com/data-management/sources) of the data pipeline section.
2.  Click **\+ New source** and click **Link** next to this source.
3.  Enter your credentials (see [Configuration](#configuration) below) and click **Next**.
4.  Select the tables you want to sync, choose a sync method and frequency, then click **Import**.

Once the syncs are complete, you can start querying this data in PostHog.

Enter your Open Exchange Rates App ID to pull foreign-exchange reference rates.

Find your App ID in your [Open Exchange Rates dashboard](https://openexchangerates.org/account/app-ids).

The free plan is restricted to the `USD` base currency - a custom base currency requires a paid plan. The `historical` table walks one request per day from the start date, so a large backfill can use a lot of your monthly request quota.

You'll be asked for:

-   **App ID**

## Sync modes

Each table can be synced in one of several modes, depending on what the source supports:

-   **Webhook** (when available) – the source pushes changes to PostHog in real time. Fastest freshness, lowest ongoing cost, and the only mode that reliably captures updates and deletes.
-   **Incremental** – only new or updated rows are synced on each run, using a cursor field (such as an `updated_at` timestamp). Cheaper than a full refresh, but deletes aren't captured.
-   **Append only** – new rows are appended using a cursor field; existing rows are never updated. Ideal for immutable, append-only tables like event logs.
-   **Full refresh** – the whole table is reloaded on every sync. Use it when a table has no reliable cursor or when you need deletions reflected.

See [sync methods](https://posthog.com/docs/data-pipelines/sources.md#sync-methods) for a full explanation of how each mode works and how to choose between them.

Some Open Exchange Rates tables sync incrementally, so later runs only fetch new or updated rows. The rest are full refresh.

## Configuration

| Option | Type | Required |
| --- | --- | --- |
| `App ID` | password | Yes |
| `Base currency` | text | No |
| `Start date (historical backfill)` | text | No |

## Supported tables

| Table | Description | Sync method | Incremental field | Primary key |
| --- | --- | --- | --- | --- |
| `currencies` | All currencies the API supports, as {code, name} rows. Full refresh only. | Full refresh | — | — |
| `latest` | Latest exchange rate per currency against the base currency. Full refresh only. | Full refresh | — | — |
| `historical` | Daily historical rates per currency, one request per day (walked from the start date). Supports incremental sync on the value date. | Incremental, Full refresh | date | — |
| `usage` | Your Open Exchange Rates plan and current request usage, as a single row. Full refresh only. | Full refresh | — | — |

## Troubleshooting

-   If the connection fails with an authorization error, the app ID is wrong, expired, or has been revoked. Create a new one, then reconnect the source.
-   If a table syncs no rows, the credential may not have access to that data. Check its permissions, then reconnect the source.

If your sync is failing or data looks wrong, see the [Data warehouse troubleshooting guide](https://posthog.com/docs/data-warehouse/troubleshooting.md). If that doesn't help, [contact support](https://us.posthog.com/#panel=support%3Asupport%3Adata_warehouse%3A%3Atrue) – we're happy to help.