Frankfurter exchange rates

The io.b3os/frankfurter pack: 5 actions with call snippets, fixture outputs, connection setup and error codes, generated from version 1.0.0.

io.b3os/frankfurter 1.0.0 · finance, currency, open-data · MIT

Foreign exchange reference rates published by the European Central Bank, through the free Frankfurter API (no key): latest and historical rates for the currencies the ECB publishes, time series between two dates, conversions and the currency list. Rates are published on working days only; weekends and holidays return the previous working day.

Every call's result carries upstream_status and timing: validate_ms, inject_ms, render_ms, upstream_ms, map_ms and total_ms. upstream is the service's time; the others are B3OS's own (call actions). The snippets below show no timing values, because a fixture records none.

Connection

No credential: a keyless public API. Calls name no connection.

Hosts it reaches: api.frankfurter.dev.

Actions

Action	Effect	MCP tool	Title
`latest-rates`	read	`frankfurter__latest-rates`	Latest rates
`historical-rates`	read	`frankfurter__historical-rates`	Rates on a date
`time-series`	read	`frankfurter__time-series`	Rates time series
`convert`	read	`frankfurter__convert`	Convert currency
`list-currencies`	read	`frankfurter__list-currencies`	List currencies

`latest-rates`

Latest rates. The most recent ECB reference rates from a base currency to all others (or the symbols you list), multiplied by amount.

Ref io.b3os/frankfurter/latest-rates@1.0.0 · effect read · no connection · MCP tool frankfurter__latest-rates

bash
curl -s https://beta-api.b3os.org/v1/actions/call \  -H "Authorization: Bearer $B3OS_API_KEY" \  -H "Content-Type: application/json" \  -d '{      "ref": "io.b3os/frankfurter/latest-rates@1",      "input": {"base": "USD", "symbols": ["EUR", "GBP", "JPY"]}    }'

ts
import { B3OS } from "@b3os/sdk";const b3os = new B3OS();const result = await b3os.actions.call({  ref: "io.b3os/frankfurter/latest-rates@1",  input: { base: "USD", symbols: ["EUR", "GBP", "JPY"] },});console.log(result.output);

python
from b3os import B3OSb3os = B3OS()result = b3os.actions.call({    "ref": "io.b3os/frankfurter/latest-rates@1",    "input": {"base": "USD", "symbols": ["EUR", "GBP", "JPY"]},})print(result["output"])

json
{  "method": "tools/call",  "params": {    "name": "frankfurter__latest-rates",    "arguments": {"base": "USD", "symbols": ["EUR", "GBP", "JPY"]}  }}

Expose the pack as tools with --packs frankfurter on the local server or ?packs=frankfurter on the remote URL, and the agent calls frankfurter__latest-rates with the action's input. The tool needs no connection. Without exposing the pack, actions_call takes the same input with ref.

Output, labeled fixture: Latest rates (response recorded 2026-10-26). From the bundle's fixtures/latest-rates.json, not a live call.

json
{  "base": "USD",  "date": "2026-10-23",  "amount": 1,  "rates": {"EUR": 0.89342, "GBP": 0.74804, "JPY": 156.8}}

When the service answers with an error, the call fails with upstream_error and pack_error.code is one of:

`pack_error.code`	Service status	Retryable	Message
`not_found`	404	no	Unknown currency, or no rates for that date (rates start on 1999-01-04).
`rate_limited`	429	yes	Frankfurter is rate limiting this address; retry shortly.

`historical-rates`

Rates on a date. ECB reference rates on a past date (the last working day on or before it), from a base currency to all others or the symbols you list.

Ref io.b3os/frankfurter/historical-rates@1.0.0 · effect read · no connection · MCP tool frankfurter__historical-rates

bash
curl -s https://beta-api.b3os.org/v1/actions/call \  -H "Authorization: Bearer $B3OS_API_KEY" \  -H "Content-Type: application/json" \  -d '{      "ref": "io.b3os/frankfurter/historical-rates@1",      "input": {"date": "2024-01-02", "base": "EUR", "symbols": ["USD", "CHF"]}    }'

ts
import { B3OS } from "@b3os/sdk";const b3os = new B3OS();const result = await b3os.actions.call({  ref: "io.b3os/frankfurter/historical-rates@1",  input: { date: "2024-01-02", base: "EUR", symbols: ["USD", "CHF"] },});console.log(result.output);

python
from b3os import B3OSb3os = B3OS()result = b3os.actions.call({    "ref": "io.b3os/frankfurter/historical-rates@1",    "input": {"date": "2024-01-02", "base": "EUR", "symbols": ["USD", "CHF"]},})print(result["output"])

json
{  "method": "tools/call",  "params": {    "name": "frankfurter__historical-rates",    "arguments": {"date": "2024-01-02", "base": "EUR", "symbols": ["USD", "CHF"]}  }}

Expose the pack as tools with --packs frankfurter on the local server or ?packs=frankfurter on the remote URL, and the agent calls frankfurter__historical-rates with the action's input. The tool needs no connection. Without exposing the pack, actions_call takes the same input with ref.

Output, labeled fixture: Rates on a date (response recorded 2026-10-26). From the bundle's fixtures/historical-rates.json, not a live call.

json
{  "base": "EUR",  "date": "2024-01-02",  "amount": 1,  "rates": {"CHF": 0.9305, "USD": 1.0956}}

When the service answers with an error, the call fails with upstream_error and pack_error.code is one of:

`pack_error.code`	Service status	Retryable	Message
`not_found`	404	no	Unknown currency, or no rates for that date (rates start on 1999-01-04).
`rate_limited`	429	yes	Frankfurter is rate limiting this address; retry shortly.

`time-series`

Rates time series. Daily ECB reference rates between two dates (end defaults to the latest), keyed by date, for the symbols you list. List few symbols over long ranges: every working day is one entry.

Ref io.b3os/frankfurter/time-series@1.0.0 · effect read · no connection · MCP tool frankfurter__time-series

bash
curl -s https://beta-api.b3os.org/v1/actions/call \  -H "Authorization: Bearer $B3OS_API_KEY" \  -H "Content-Type: application/json" \  -d '{      "ref": "io.b3os/frankfurter/time-series@1",      "input": {        "start_date": "2026-10-19",        "end_date": "2026-10-23",        "base": "USD",        "symbols": ["EUR"]      }    }'

ts
import { B3OS } from "@b3os/sdk";const b3os = new B3OS();const result = await b3os.actions.call({  ref: "io.b3os/frankfurter/time-series@1",  input: {    start_date: "2026-10-19",    end_date: "2026-10-23",    base: "USD",    symbols: ["EUR"],  },});console.log(result.output);

python
from b3os import B3OSb3os = B3OS()result = b3os.actions.call({    "ref": "io.b3os/frankfurter/time-series@1",    "input": {        "start_date": "2026-10-19",        "end_date": "2026-10-23",        "base": "USD",        "symbols": ["EUR"],    },})print(result["output"])

json
{  "method": "tools/call",  "params": {    "name": "frankfurter__time-series",    "arguments": {      "start_date": "2026-10-19",      "end_date": "2026-10-23",      "base": "USD",      "symbols": ["EUR"]    }  }}

Expose the pack as tools with --packs frankfurter on the local server or ?packs=frankfurter on the remote URL, and the agent calls frankfurter__time-series with the action's input. The tool needs no connection. Without exposing the pack, actions_call takes the same input with ref.

Output, labeled fixture: Rates time series (response recorded 2026-10-26). From the bundle's fixtures/time-series.json, not a live call.

json
{  "base": "USD",  "start_date": "2026-10-19",  "end_date": "2026-10-23",  "rates": {    "2026-10-19": {"EUR": 0.89087},    "2026-10-20": {"EUR": 0.89166},    "2026-10-21": {"EUR": 0.89015},    "2026-10-22": {"EUR": 0.89246},    "2026-10-23": {"EUR": 0.89342}  }}

When the service answers with an error, the call fails with upstream_error and pack_error.code is one of:

`pack_error.code`	Service status	Retryable	Message
`not_found`	404	no	Unknown currency, or no rates for that date (rates start on 1999-01-04).
`rate_limited`	429	yes	Frankfurter is rate limiting this address; retry shortly.

`convert`

Convert currency. Convert an amount from one currency to another at the latest ECB reference rate (or on a past date), returning the converted amount and the rate.

Ref io.b3os/frankfurter/convert@1.0.0 · effect read · no connection · MCP tool frankfurter__convert

bash
curl -s https://beta-api.b3os.org/v1/actions/call \  -H "Authorization: Bearer $B3OS_API_KEY" \  -H "Content-Type: application/json" \  -d '{      "ref": "io.b3os/frankfurter/convert@1",      "input": {"amount": 250, "from": "GBP", "to": "USD"}    }'

ts
import { B3OS } from "@b3os/sdk";const b3os = new B3OS();const result = await b3os.actions.call({  ref: "io.b3os/frankfurter/convert@1",  input: { amount: 250, from: "GBP", to: "USD" },});console.log(result.output);

python
from b3os import B3OSb3os = B3OS()result = b3os.actions.call({    "ref": "io.b3os/frankfurter/convert@1",    "input": {"amount": 250, "from": "GBP", "to": "USD"},})print(result["output"])

json
{  "method": "tools/call",  "params": {    "name": "frankfurter__convert",    "arguments": {"amount": 250, "from": "GBP", "to": "USD"}  }}

Expose the pack as tools with --packs frankfurter on the local server or ?packs=frankfurter on the remote URL, and the agent calls frankfurter__convert with the action's input. The tool needs no connection. Without exposing the pack, actions_call takes the same input with ref.

Output, labeled fixture: Convert currency (response recorded 2026-10-26). From the bundle's fixtures/convert.json, not a live call.

json
{  "amount": 250,  "from": "GBP",  "to": "USD",  "date": "2026-10-23",  "result": 334.2,  "rate": 1.3368}

When the service answers with an error, the call fails with upstream_error and pack_error.code is one of:

`pack_error.code`	Service status	Retryable	Message
`not_found`	404	no	Unknown currency, or no rates for that date (rates start on 1999-01-04).
`rate_limited`	429	yes	Frankfurter is rate limiting this address; retry shortly.

`list-currencies`

List currencies. Every currency Frankfurter has ECB rates for, as ISO 4217 code to English name.

Ref io.b3os/frankfurter/list-currencies@1.0.0 · effect read · no connection · MCP tool frankfurter__list-currencies

bash
curl -s https://beta-api.b3os.org/v1/actions/call \  -H "Authorization: Bearer $B3OS_API_KEY" \  -H "Content-Type: application/json" \  -d '{"ref": "io.b3os/frankfurter/list-currencies@1", "input": {}}'

ts
import { B3OS } from "@b3os/sdk";const b3os = new B3OS();const result = await b3os.actions.call({ ref: "io.b3os/frankfurter/list-currencies@1", input: {} });console.log(result.output);

python
from b3os import B3OSb3os = B3OS()result = b3os.actions.call({"ref": "io.b3os/frankfurter/list-currencies@1", "input": {}})print(result["output"])

json
{  "method": "tools/call",  "params": {"name": "frankfurter__list-currencies", "arguments": {}}}

Expose the pack as tools with --packs frankfurter on the local server or ?packs=frankfurter on the remote URL, and the agent calls frankfurter__list-currencies with the action's input. The tool needs no connection. Without exposing the pack, actions_call takes the same input with ref.

Output, labeled fixture: List currencies (response recorded 2026-10-26). From the bundle's fixtures/list-currencies.json, not a live call.

json
{  "currencies": {    "AUD": "Australian Dollar",    "BRL": "Brazilian Real",    "CAD": "Canadian Dollar",    "CHF": "Swiss Franc",    "CNY": "Chinese Renminbi Yuan",    "CZK": "Czech Koruna",    "DKK": "Danish Krone",    "EUR": "Euro",    "GBP": "British Pound",    "HKD": "Hong Kong Dollar",    "HUF": "Hungarian Forint",    "IDR": "Indonesian Rupiah",    "ILS": "Israeli New Shekel",    "INR": "Indian Rupee",    "ISK": "Icelandic Króna",    "JPY": "Japanese Yen",    "KRW": "South Korean Won",    "MXN": "Mexican Peso",    "MYR": "Malaysian Ringgit",    "NOK": "Norwegian Krone",    "NZD": "New Zealand Dollar",    "PHP": "Philippine Peso",    "PLN": "Polish Złoty",    "RON": "Romanian Leu",    "SEK": "Swedish Krona",    "SGD": "Singapore Dollar",    "THB": "Thai Baht",    "TRY": "Turkish Lira",    "USD": "United States Dollar",    "ZAR": "South African Rand"  }}

When the service answers with an error, the call fails with upstream_error and pack_error.code is one of:

`pack_error.code`	Service status	Retryable	Message
`not_found`	404	no	Unknown currency, or no rates for that date (rates start on 1999-01-04).
`rate_limited`	429	yes	Frankfurter is rate limiting this address; retry shortly.

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