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SkillMedev/skills

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.

What is skills?

skills is a Claude Code agent skill that 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.

Works with~Claude Code~Codex CLI~Cursor
npx skills add https://github.com/SkillMedev/skills/tree/HEAD/skills/finance-fx
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Documentation

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

  1. 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.
  2. 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

  1. Fiat or crypto? Fiat → Frankfurter. Crypto → CoinGecko. Crypto→fiat conversion is one CoinGecko call (vs_currencies=eur), not two hops.
  2. 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.
  3. 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.
  4. 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).

Individual skills in this repo

This repo contains 11 individual skills — each has its own dedicated page.

SkillMedev/skills

Designs REST API surfaces - resource naming, HTTP method and status-code semantics, error shapes, pagination, and filtering - and delivers an endpoint spec a consumer can build against without asking questions. Use when someone asks "how should I name this endpoint", "what status code should this return", "should this be PUT or PATCH", "how do I paginate this list", or is reviewing an API before it ships to external consumers. Do NOT use for planning breaking-change rollouts and deprecation windows - use api-versioning-strategist instead; for GraphQL type and resolver design - use graphql-schema instead; for generating client SDKs from an existing spec - use api-client-generator instead; for designing inbound webhook endpoints - use webhook-receiver-hardener instead.

SkillMedev/skills

Turns data and charts into a decision-driving narrative structured as headline finding, trend, implication, and recommended action - with finding-led chart titles, context for every number, annotation guidance, and honest flags on any conclusion the data cannot support. Use when someone says "turn these numbers into a story", "what's the takeaway from this data", "help me present these results to leadership", or has charts but no narrative. Do NOT use for compressing a long document into a one-pager - use executive-summary instead - or for running the analysis that produces the findings - use eda-playbook instead.

SkillMedev/skills

Builds a driver-based FP&A operating model linking business inputs to P&L, balance sheet, and cash flow outputs. Use when building an annual plan, preparing investor materials, running scenario analysis, or stress-testing the business.

SkillMedev/skills

Use when a task needs live geographic lookups - "geocode this address", "what's at these coordinates" (reverse geocoding), "lat/lon for this city", "which country/state is this ZIP or postal code in", or "country facts: capital, currency, population, flag". Nominatim (OpenStreetMap) is the geocoding default; Zippopotam for postal codes; APICountries for country facts. All keyless. Do NOT use for weather at a location - use weather-climate instead; do NOT use for country-level statistics over time (GDP, population trends) - use government-open-data instead; if the request is a vague "I need live data", route through public-data-api-picker.

SkillMedev/skills

Runs the full Getting Things Done loop - capture, clarify, organize, reflect, engage - building a trusted system of context lists, a projects list with defined next actions, and a weekly review habit. Use when someone says "I'm overwhelmed and things are slipping through the cracks", "set up GTD for me", "help me do a brain dump and organize it", or "my to-do list is a mess". Do NOT use for just running the weekly review ritual itself - use weekly-review instead - or for clearing an email backlog - use inbox-zero.

SkillMedev/skills

Processes any email backlog to zero using the 4Ds - Delete, Delegate, Defer, Do - with a mass-archive strategy for the obvious, a touch-each-email-once discipline, and a keep-it-clear system of batched processing windows, ruthless unsubscribing, filters, and a minimal folder setup. Use when someone says "I have 5,000 unread emails", "help me get to inbox zero", "email is eating my whole day", or treats their inbox as a to-do list. Do NOT use for drafting the reply emails themselves or prioritization rules for an ongoing support queue - use email-triage instead - or for protecting focus time around the email windows - use deep-work-planner instead.

SkillMedev/skills

Runs structured coaching sessions using values clarification and the GROW model, ending every session with one committed action, a deadline, and an if-then plan for the likely obstacle. Use when someone says "I feel stuck in my life", "help me figure out what I want", "hold me accountable to my goals", or "coach me through this decision". Do NOT use for building a stress toolkit - use stress-management instead - or a journaling practice - use journal-framework; for a standing goal-tracking system, use goals-accountability. Coaching, not therapy: signs of clinical distress route to a licensed professional.

SkillMedev/skills

Classifies incident severity (SEV1-4) using impact, scope, and urgency signals and decides who to page. Use when an alert fires or a report comes in and a severity call must be made quickly.

SkillMedev/skills

Use the Skill Me catalog from inside any conversation - discover, install, and manage Claude skills through the Skill Me MCP, and load installed skills automatically each session.

SkillMedev/skills

Writes and tunes PySpark jobs - join strategy and broadcast size limits, shuffle-partition sizing, skew diagnosis and salting, UDF avoidance, caching, and output file layout - with concrete size and skew thresholds. Use when someone asks "why is my Spark job slow", "should I broadcast this join", "one task takes forever while the rest finish", "my job OOMs during a join", or is writing a new PySpark ETL job. Do NOT use for Kafka topic, consumer-group, or streaming-pipeline design - use kafka-pipelines instead; do NOT use for single-machine dataframe work that fits in memory - use pandas-expert instead.

SkillMedev/skills

Builds clean, performant, accessible SwiftUI views with correct state ownership, scoped invalidation, and smooth list scrolling, and reviews existing SwiftUI code against a concrete frame-time and re-render budget. Use when someone asks "why does my SwiftUI list stutter", "should this be @State or @Observable", "my whole screen re-renders when one row changes", "how do I animate this transition", or wants a SwiftUI view built or refactored. Do NOT use for cross-platform React Native apps - use react-native-pro instead; do NOT use for Flutter widget trees - use flutter-widget-architect instead; do NOT use for Android Compose UIs - use jetpack-compose-builder instead.

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