Finance fx

Skill SkillMedev/skills/skills/finance-fx

The open Skill Me catalog — every hosted skill as a portable, MIT-licensed SKILL.md

Install

npx -y skills add SkillMedev/skills --skill finance-fx

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

4 stars4 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.

What its author says it does

Copied from the file, not written here

Use when a task needs live or historical money data - "convert USD to EUR", "current/past exchange rate", "FX rate on this date / over this range", or "current price of Bitcoin/Ethereum, market cap, 24h change". Frankfurter (ECB reference rates, no key) is the FX default; CoinGecko's free keyless tier covers crypto. Do NOT use for stock quotes or equities - no keyless stock API survives verification, say so instead of guessing; do NOT use for country economic indicators like GDP or inflation series - use government-open-data instead; if the request is a vague "I need live data", route through public-data-api-picker.

SKILL.md

5.0 KB, as published. Nobody here has run it

Finance & FX Data

Fetch exchange rates and crypto prices with keyless calls. The mistake this prevents: reaching for exchangerate.host, Fixer, or Alpha Vantage from training memory - all key-walled now - or hand-waving a stale rate from training data into a real calculation.

Ranked APIs

Frankfurter (api.frankfurter.dev) - DEFAULT for fiat FX. European Central Bank reference rates, ~30 major currencies, history back to 1999, time series, no key, no rate limit worth worrying about.
CoinGecko free tier (api.coingecko.com) - crypto prices, market caps, 24h change for thousands of coins. No key, but a tight limit: roughly 5-15 calls/min from an anonymous IP. Batch ids into one call; on 429, back off 60s.

Procedure

Fiat or crypto? Fiat → Frankfurter. Crypto → CoinGecko. Crypto→fiat conversion is one CoinGecko call (vs_currencies=eur), not two hops.
Date the rate. ECB reference rates update ~16:00 CET on business days; the response's date field tells you which day you actually got. Weekend/holiday requests return the previous business day - quote that date, don't present it as today's.
Use CoinGecko ids, not tickers. The ids param wants bitcoin, ethereum, solana - not BTC/ETH. For an unfamiliar coin, resolve once via /api/v3/search?query={name} → coins[0].id.
Never do FX math from memory. If the task multiplies money by a rate, the rate comes from one of these calls, with the date attached.

Ask the user only if missing: currency pair or coin (no default), date/range (default: latest), amount (default: 1).

URL templates + real response shapes

Latest FX rate:

https://api.frankfurter.dev/v1/latest?base=USD&symbols=EUR,GBP,JPY

{"amount":1.0,"base":"USD","date":"<last business day>","rates":{"EUR":0.87352,"GBP":0.74878,"JPY":161.15}}

Convert an amount server-side with &amount=250 - rates comes back pre-multiplied.

Historical / time series:

https://api.frankfurter.dev/v1/2024-01-15?base=USD&symbols=EUR          ← one date
https://api.frankfurter.dev/v1/2024-01-02..2024-01-31?base=USD&symbols=EUR   ← range
https://api.frankfurter.dev/v1/currencies                               ← code → name map

Range shape: {"rates":{"2024-01-02":{"EUR":0.91274},"2024-01-03":{"EUR":0.91583}}} - keyed by date, business days only (a full year returns ~256 daily points; no weekend keys, so don't treat gaps as missing data). Omit the end date (/2024-01-02..) to run to present.

Crypto spot price:

https://api.coingecko.com/api/v3/simple/price?ids=bitcoin,ethereum&vs_currencies=usd&include_24hr_change=true

{"bitcoin":{"usd":63289,"usd_24h_change":1.19},"ethereum":{"usd":1790.89,"usd_24h_change":1.90}}

Unknown ids are silently dropped from the response - a missing key means a wrong id, not a null price.

Crypto market table (rank, cap, supply):

https://api.coingecko.com/api/v3/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=20&page=1

Array of {"id","symbol","name","current_price","market_cap","market_cap_rank","price_change_percentage_24h","circulating_supply","ath"} - one call replaces twenty /simple/price calls; prefer it for any list.

Deliverable

The rate or price with its date/timestamp and source named, plus the exact URL used. Any conversion shows the arithmetic: 250 USD × 0.87352 (ECB, <rate date>) = 218.38 EUR.

Do NOT use - reach for X instead

exchangerate.host - every request now requires an access_key; verified failing keyless. Frankfurter replaces it.
Fixer, Alpha Vantage, Finnhub, Polygon, OpenExchangeRates - key-walled; do not send a user to sign up when Frankfurter/CoinGecko cover the need.
Stock/equity quotes - nothing keyless survives verification. Say that plainly and name the paid options rather than fabricating a price.
GDP, inflation, unemployment, trade series - government-open-data.
Financial advice - this skill fetches numbers; buy/sell/allocation judgments are out of scope. Present data, not recommendations.

Quality bar

Every number carries its date and source; no rate or price originates from training memory.
Frankfurter's ~30-currency ceiling respected - exotic pairs (e.g. NGN, VND) are declared unsupported, not approximated.
CoinGecko calls are batched; a 429 produces a backoff, not a retry loop.

Sourced and liveness-verified from the public-apis project (MIT).