Name: Seiche Reference FX API | ECB EUR Reference Rates
Brand: liquilens
SKU: api-liquilens-seiche-reference-fx
Availability: InStock
Author: API Market

Mrinal Singh Meena

# Seiche Reference FX API

## Overview

The Seiche Reference FX API serves the European Central Bank (ECB) daily euro reference rates for four currencies: US dollar, British pound, Japanese yen and Indian rupee. Each of the four endpoints returns one complete series as a CSV file, with every value stated as units of that currency per one euro. The USD, GBP and JPY histories start on 4 January 1999 and the INR history on 2 January 2009, and each file runs to the most recent ECB publication. Every file starts with a comment header that records the series, unit, retrieval time, last observation date and a staleness flag, so you can confirm freshness before you use the numbers.

It is built for financial analysts, data engineers, researchers and developers who need clean, dated EUR reference rates in spreadsheets, notebooks, BI tools or scheduled pipelines without parsing the ECB XML feed themselves. Values are passed through exactly as the ECB publishes them, with no conversion, interpolation or adjustment, and dates without a publication (weekends and TARGET holidays) are simply absent. These are informational reference rates, not executable quotes or investment advice.

## Features

*   **4 currency series**: USD, GBP, JPY and INR per EUR, one fixed GET endpoint each
*   **Full history in one call**: Every observation from 1999 (INR from 2009) to the latest ECB business day, around 4,500 to 7,100 rows per file
*   **Freshness metadata**: The comment header carries `retrieved_at`, `last_observation` and a `staleness` flag
*   **Source provenance**: Each file names the ECB remote series id (for example `EXR/D.USD.EUR.SP00.A`) and carries the ECB source credit
*   **Unmodified values**: No currency conversion, interpolation, gap filling or economic adjustment
*   **Plain CSV**: `text/csv` output that loads directly into Excel, Google Sheets, pandas or R
*   **No parameters**: Nothing to configure: call the series you need and parse `date,value`
*   **Rate limit**: 1 request per second on the free trial plan

## Use Cases

*   **Financial research**: Load EUR reference histories into notebooks and reports with source dates attached
*   **Accounting and reporting**: Look up the official ECB reference rate for a given date when restating EUR amounts
*   **Data quality checks**: Schedule a daily pull and alert when `staleness` is no longer fresh
*   **Dashboards and BI**: Chart long-run EUR/USD, EUR/GBP, EUR/JPY and EUR/INR trends
*   **Backtesting and modelling**: Use 25+ years of daily observations as a clean, gap-honest input series
*   **Cross-rate analysis**: Derive USD/INR or GBP/JPY from the shared EUR base in your own code, keeping the originals

## Pricing

The Free plan is a 7-day trial with up to 1,000 calls. PRO costs $5 per month and includes 10,000 calls across all four endpoints. Both plans have a hard call limit, no overage calls, and a rate limit of 1 request per second.

**Before subscribing:** The original ECB reference-rate information is available free of charge from the [European Central Bank](https://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml). The paid plan provides API.market gateway access to Seiche's dated CSV histories. Seiche converts the source feed to CSV; values are not converted to another currency, interpolated or economically adjusted. Each response retains the ECB source credit and free-data notice. No ECB affiliation or endorsement is claimed. [ECB reuse terms](https://www.ecb.europa.eu/services/using-our-site/disclaimer/html/index.en.html).

## API Documentation

### Base URL

All requests go through the API.market gateway at this base URL:

```
https://prod.api.market/api/v1/liquilens/seiche-reference-fx
```

### Authentication

Every request needs your API.market key in the `x-api-market-key` header:

```
x-api-market-key: YOUR_API_KEY
```

Replace `YOUR_API_KEY` with your actual API key.

### Endpoints

#### 1. USD per EUR history

Returns the full daily ECB reference-rate history for USD per euro, from 4 January 1999 to the latest published business day, as CSV. The file opens with a `#` comment header (series id, ECB remote id, unit, retrieval time, last observation, staleness and source credit) followed by `date,value` rows. There are no path or query parameters.

**Method:** `GET`

**Endpoint:** `/api/series/ECBFX_USD.csv`

**Parameters:**

| Name | In | Description | Type | Required | Default | Max Value |
|---|---|---|---|---|---|---|
| x-api-market-key | header | Your API.market API key | string | Yes | - | - |

**Example Request:**

```bash
curl -X GET "https://prod.api.market/api/v1/liquilens/seiche-reference-fx/api/series/ECBFX_USD.csv" \
  -H "x-api-market-key: YOUR_API_KEY"
```

**Example Response (200 OK, abridged):**

```csv
# Seiche series ECBFX_USD: USD per euro (ECB daily reference rate)
# source: ecb_fx (remote id EXR/D.USD.EUR.SP00.A), unit: USD/EUR, cadence: daily, native lag: published same day to next business day
# retrieved_at: 2026-10-07T15:33:58+00:00, last_observation: 2026-10-07, staleness: fresh
# vintage: the upstream's current print, not a reconstructed as-of view; lightly revised series revise here too
# cite: Seiche (https://seiche.info/methodology); credit for the data belongs to the source above
# Source: European Central Bank. Reference data is freely available from the ECB; not executable quotes. https://www.ecb.europa.eu/services/using-our-site/disclaimer/html/index.en.html
date,value
1999-01-04,1.1789
1999-01-05,1.179
...
2026-10-05,1.1204
2026-10-06,1.1269
2026-10-07,1.1177
```

#### 2. GBP per EUR history

Returns the full daily ECB reference-rate history for GBP per euro, from 4 January 1999 to the latest published business day, as CSV. The file opens with a `#` comment header (series id, ECB remote id, unit, retrieval time, last observation, staleness and source credit) followed by `date,value` rows. There are no path or query parameters.

**Method:** `GET`

**Endpoint:** `/api/series/ECBFX_GBP.csv`

**Parameters:**

| Name | In | Description | Type | Required | Default | Max Value |
|---|---|---|---|---|---|---|
| x-api-market-key | header | Your API.market API key | string | Yes | - | - |

**Example Request:**

```bash
curl -X GET "https://prod.api.market/api/v1/liquilens/seiche-reference-fx/api/series/ECBFX_GBP.csv" \
  -H "x-api-market-key: YOUR_API_KEY"
```

**Example Response (200 OK, abridged):**

```csv
# Seiche series ECBFX_GBP: GBP per euro (ECB daily reference rate)
# source: ecb_fx (remote id EXR/D.GBP.EUR.SP00.A), unit: GBP/EUR, cadence: daily, native lag: published same day to next business day
# retrieved_at: 2026-10-07T15:33:58+00:00, last_observation: 2026-10-07, staleness: fresh
# vintage: the upstream's current print, not a reconstructed as-of view; lightly revised series revise here too
# cite: Seiche (https://seiche.info/methodology); credit for the data belongs to the source above
# Source: European Central Bank. Reference data is freely available from the ECB; not executable quotes. https://www.ecb.europa.eu/services/using-our-site/disclaimer/html/index.en.html
date,value
1999-01-04,0.7111
1999-01-05,0.7122
...
2026-10-05,0.8472
2026-10-06,0.8488
2026-10-07,0.84645
```

#### 3. JPY per EUR history

Returns the full daily ECB reference-rate history for JPY per euro, from 4 January 1999 to the latest published business day, as CSV. The file opens with a `#` comment header (series id, ECB remote id, unit, retrieval time, last observation, staleness and source credit) followed by `date,value` rows. There are no path or query parameters.

**Method:** `GET`

**Endpoint:** `/api/series/ECBFX_JPY.csv`

**Parameters:**

| Name | In | Description | Type | Required | Default | Max Value |
|---|---|---|---|---|---|---|
| x-api-market-key | header | Your API.market API key | string | Yes | - | - |

**Example Request:**

```bash
curl -X GET "https://prod.api.market/api/v1/liquilens/seiche-reference-fx/api/series/ECBFX_JPY.csv" \
  -H "x-api-market-key: YOUR_API_KEY"
```

**Example Response (200 OK, abridged):**

```csv
# Seiche series ECBFX_JPY: JPY per euro (ECB daily reference rate)
# source: ecb_fx (remote id EXR/D.JPY.EUR.SP00.A), unit: JPY/EUR, cadence: daily, native lag: published same day to next business day
# retrieved_at: 2026-10-07T15:33:58+00:00, last_observation: 2026-10-07, staleness: fresh
# vintage: the upstream's current print, not a reconstructed as-of view; lightly revised series revise here too
# cite: Seiche (https://seiche.info/methodology); credit for the data belongs to the source above
# Source: European Central Bank. Reference data is freely available from the ECB; not executable quotes. https://www.ecb.europa.eu/services/using-our-site/disclaimer/html/index.en.html
date,value
1999-01-04,133.73
1999-01-05,130.96
...
2026-10-05,177.28
2026-10-06,178.15
2026-10-07,176.85
```

#### 4. INR per EUR history

Returns the full daily ECB reference-rate history for INR per euro, from 2 January 2009 to the latest published business day, as CSV. The file opens with a `#` comment header (series id, ECB remote id, unit, retrieval time, last observation, staleness and source credit) followed by `date,value` rows. There are no path or query parameters.

**Method:** `GET`

**Endpoint:** `/api/series/ECBFX_INR.csv`

**Parameters:**

| Name | In | Description | Type | Required | Default | Max Value |
|---|---|---|---|---|---|---|
| x-api-market-key | header | Your API.market API key | string | Yes | - | - |

**Example Request:**

```bash
curl -X GET "https://prod.api.market/api/v1/liquilens/seiche-reference-fx/api/series/ECBFX_INR.csv" \
  -H "x-api-market-key: YOUR_API_KEY"
```

**Example Response (200 OK, abridged):**

```csv
# Seiche series ECBFX_INR: INR per euro (ECB daily reference rate)
# source: ecb_fx (remote id EXR/D.INR.EUR.SP00.A), unit: INR/EUR, cadence: daily, native lag: published same day to next business day
# retrieved_at: 2026-10-07T15:33:58+00:00, last_observation: 2026-10-07, staleness: fresh
# vintage: the upstream's current print, not a reconstructed as-of view; lightly revised series revise here too
# cite: Seiche (https://seiche.info/methodology); credit for the data belongs to the source above
# Source: European Central Bank. Reference data is freely available from the ECB; not executable quotes. https://www.ecb.europa.eu/services/using-our-site/disclaimer/html/index.en.html
date,value
2009-01-02,67.125
2009-01-05,65.893
...
2026-10-05,107.8915
2026-10-06,108.6615
2026-10-07,108.1165
```

## Status Codes

| Code | Status | Description |
|---|---|---|
| 200 | OK | The CSV series was returned. Check `last_observation` and `staleness` in the header before relying on the latest value. |
| 400 | Bad Request | The `x-api-market-key` header is missing from the request. |
| 401 | Unauthorized | The `x-api-market-key` value is invalid or expired. |
| 403 | Forbidden | You are not subscribed to a plan that includes this endpoint, or the upstream source has restricted redistribution of the series. No observations are returned. |
| 404 | Not Found | The path does not match one of the four series endpoints. Only USD, GBP, JPY and INR are available. |
| 429 | Too Many Requests | You exceeded 1 request per second or used up your plan quota. Wait and retry, or upgrade your plan. |
| 500 | Internal Server Error | An unexpected error occurred while building the series. Retry after a short delay. |
| 503 | Service Unavailable | The source history is not available yet. Treat the series as unavailable rather than substituting zero or stale values. |

## Rate Limits

Both plans allow 1 request per second. The free trial includes 1,000 API calls over 7 days, and PRO includes 10,000 calls per month with a hard limit. Each call returns a whole series, and the ECB publishes once per business day (around 16:00 CET), so one call per series per day is enough for most workflows. Requests above the limit return `429 Too Many Requests`; throttle your client, back off before retrying, and honour any `Retry-After` header.

## FAQ

*   **Which way round are the rates quoted?**

    Every value is units of the named currency per one euro. A USD value of 1.1177 means 1 EUR = 1.1177 USD. Invert it yourself if you need EUR per USD, and label the result as derived.

*   **Why are some dates missing?**

    The ECB publishes only on TARGET business days, so weekends and TARGET holidays have no row. Missing dates are left out rather than filled in.

*   **How do I know the data is current?**

    Read `last_observation` and `staleness` in the comment header. A 200 response means the request worked, not that the latest value is from today.

*   **Can I request a date range or a different currency?**

    No. Each endpoint returns the full history for one currency, and only USD, GBP, JPY and INR are offered. Filter by date in your own code.

*   **Why does the INR series start in 2009?**

    The ECB began publishing a daily INR reference rate on 2 January 2009, so that is the first available observation.

*   **Are these rates I can trade at?**

    No. ECB reference rates are published for information only. They are not executable quotes and are not investment advice.

*   **Do I need to credit the source?**

    Yes. The data comes from the European Central Bank and is reused under the ECB copyright policy. Keep the comment header and source credit when you redistribute the output.

*   **How do I parse the CSV and skip the header?**

    Skip lines starting with `#`, then read `date,value`. In pandas: `pd.read_csv(url_or_file, comment='#')`.

## Contact Us

If you have any questions or need assistance, you can reach out to us through the embedded chat on the bottom right corner of the page or send an email to hello@magicapi.com.

Daily ECB EUR-base reference histories for USD, GBP, JPY and INR. Dated CSV observations with source attribution, units and explicit availability.