Linking Exchange Rates API as a source

Alpha release

This source is currently in alpha. The interface and available tables may change.

The Exchange Rates API connector syncs foreign-exchange reference rates into PostHog, so you can analyze currency data alongside your product data.

Prerequisites

You need an exchangeratesapi.io account with an access key. The free plan is restricted to the EUR base currency, and the timeseries table may not be available on every plan – a custom base currency requires a paid plan.

Adding a data source

In PostHog, go to the Sources tab of the data pipeline section.
Click + New source and click Link next to this source.
Enter your credentials (see Configuration below) and click Next.
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.

When linking Exchange Rates API, you'll need:

Access key – create one in your exchangeratesapi.io dashboard.
Base currency – optional. Defaults to EUR. A custom base currency requires a paid plan.
Start date – optional. The start date for the timeseries backfill, in YYYY-MM-DD format. The timeseries table is capped at a 365-day range per request and backfills are chunked automatically.

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 for a full explanation of how each mode works and how to choose between them.

Configuration

Option	Type	Required
`Access key`	password	Yes
`Base currency`	text	No
`Start date (timeseries backfill)`	text	No

Supported tables

Table	Description	Sync method	Incremental field	Primary key
`symbols`	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	—	—
`timeseries`	Daily historical rates per currency over a date range (max 365 days per request, chunked). Supports incremental sync on the value date.	Incremental, Full refresh	date	—

Troubleshooting

If you see an authentication error, your access key may be invalid or revoked. Create a new key in your exchangeratesapi.io dashboard, then reconnect.
If you see a permission error, your plan may not allow the request (for example a non-EUR base currency or the timeseries endpoint on the free plan). Upgrade your plan or adjust the source settings, then reconnect.

If your sync is failing or data looks wrong, see the Data warehouse troubleshooting guide. If that doesn't help, contact support – we're happy to help.