API Research
Find and validate real, live data sources. No hardcoded data allowed.
Step 1: Search for APIs
Web search for APIs
web_search "<topic> free API" web_search "<topic> public API documentation" web_search "<topic> real-time data API" web_search "<topic> JSON API no auth"
Step 2: Validate API Endpoints
Test each potential API:
Test endpoint directly
curl -s "<api_endpoint>" | head -c 500
Check response
✅ Returns JSON with real data
✅ No authentication required (or has free tier)
✅ Response time < 5 seconds
❌ Returns error or empty
❌ Requires paid API key
Common Free Data Sources
Finance & Crypto
API Endpoint Notes
DeFiLlama https://api.llama.fi/v2/chains
TVL, yields, derivatives
CoinGecko https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=usd
Prices, trending
Yahoo Finance https://query1.finance.yahoo.com/v8/finance/chart/AAPL
Stocks (unofficial)
Exchange Rates https://api.exchangerate.host/latest
Currency rates
Weather & Environment
API Endpoint Notes
Open-Meteo https://api.open-meteo.com/v1/forecast?latitude=52&longitude=13&current_weather=true
No key needed
wttr.in https://wttr.in/London?format=j1
Simple weather
NOAA Space Weather https://services.swpc.noaa.gov/products/noaa-scales.json
Space weather
Geology & Space
API Endpoint Notes
USGS Earthquakes https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/significant_week.geojson
Real-time
NASA APOD https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY
Demo key works
ISS Location http://api.open-notify.org/iss-now.json
Real-time position
General Purpose
API Endpoint Notes
IP Geolocation http://ip-api.com/json/
IP info
Countries https://restcountries.com/v3.1/all
Country data
Universities http://universities.hipolabs.com/search?country=united+states
School data
Random User https://randomuser.me/api/
Test data
Quotes https://api.quotable.io/random
Random quotes
Jokes https://v2.jokeapi.dev/joke/Any
Random jokes
Books https://openlibrary.org/search.json?q=lord+of+the+rings
Book data
Wikipedia https://en.wikipedia.org/api/rest_v1/page/summary/Claude_(AI)
Summaries
GitHub https://api.github.com/users/langoustine69
User/repo data
Sports & Entertainment
API Endpoint Notes
ESPN https://site.api.espn.com/apis/site/v2/sports/football/nfl/scoreboard
Live scores
OMDB https://www.omdbapi.com/?t=inception&apikey=<free_key>
Movies (free key)
Step 3: Design Endpoints
Based on validated APIs, design 6 endpoints:
Endpoint Type Price Data Source
overview
Free $0 Quick summary for discovery
lookup
Paid $0.001 Single item by ID/name
search
Paid $0.002 Filtered list query
top
Paid $0.002 Rankings/leaderboards
compare
Paid $0.003 Multi-item comparison
report
Paid $0.005 Comprehensive analysis
Output
Provide:
-
Validated API endpoints (tested, working)
-
6 endpoint designs with descriptions
-
Data mapping (which API feeds which endpoint)
Red Flags
-
❌ API requires paid key with no free tier
-
❌ Rate limits too strict (< 100 req/day)
-
❌ Data is stale (not updated regularly)
-
❌ Endpoint returns HTML instead of JSON
-
❌ Requires OAuth/complex auth flow
Next Step
→ Use lucid-agents-sdk skill to create the agent code