9 Free APIs You Probably Didn't Know Existed

#api #python #tutorial #webdev

Everyone knows about the GitHub API and Google Maps API.

But these 9 APIs fly under the radar — and they're incredibly useful.

1. Open-Meteo — Weather Without API Key

Most weather APIs require registration. Open-Meteo doesn't.

import requests

# Get weather for any city — no key, no registration
resp = requests.get('https://api.open-meteo.com/v1/forecast', params={
    'latitude': 51.5, 'longitude': -0.1,  # London
    'current': 'temperature_2m,wind_speed_10m',
    'daily': 'temperature_2m_max,temperature_2m_min',
    'timezone': 'auto'
})
data = resp.json()
print(f"London: {data['current']['temperature_2m']}°C")

16-day forecast + historical data. Free forever.

2. Shodan InternetDB — IP Intelligence Without Key

Shodan's premium API costs $59/month. But InternetDB is free.

def scan_ip(ip):
    data = requests.get(f'https://internetdb.shodan.io/{ip}').json()
    print(f"Open ports: {data.get('ports', [])}")
    print(f"Known CVEs: {data.get('vulns', [])}")
    print(f"Hostnames: {data.get('hostnames', [])}")

scan_ip('8.8.8.8')

Ports, vulnerabilities, hostnames — one API call.

3. crt.sh — SSL Certificate Search

Find EVERY certificate ever issued for a domain.

def find_certs(domain):
    resp = requests.get(f'https://crt.sh/?q=%25.{domain}&output=json')
    certs = resp.json()
    subdomains = set()
    for cert in certs:
        name = cert.get('name_value', '')
        for sub in name.split('\n'):
            subdomains.add(sub)
    return sorted(subdomains)

# Find all subdomains of any company
subs = find_certs('example.com')
print(f"Found {len(subs)} subdomains")

Used by security researchers for subdomain enumeration.

4. Wayback Machine API — Website Time Travel

def check_archive(url):
    resp = requests.get(f'http://archive.org/wayback/available?url={url}')
    snapshot = resp.json().get('archived_snapshots', {}).get('closest', {})
    if snapshot:
        print(f"Archived: {snapshot['url']}")
        print(f"Date: {snapshot['timestamp']}")

check_archive('google.com')  # See Google's earliest snapshot

5. OpenAlex — 250M Academic Papers

Google Scholar has no API. OpenAlex does.

resp = requests.get('https://api.openalex.org/works', params={
    'search': 'machine learning healthcare',
    'per_page': 3,
    'sort': 'cited_by_count:desc'
})
for w in resp.json()['results']:
    print(f"{w['title'][:60]} — {w['cited_by_count']} citations")

No key needed. Our toolkit

6. Unpaywall — Legal Free PDFs

def find_pdf(doi):
    resp = requests.get(f'https://api.unpaywall.org/v2/{doi}',
                        params={'email': 'you@email.com'})
    data = resp.json()
    if data.get('is_oa'):
        return data['best_oa_location']['url_for_pdf']
    return None

pdf = find_pdf('10.1038/s41586-021-03819-2')
print(f"Free PDF: {pdf}")

7. ip-api.com — IP Geolocation (Completely Free)

def geolocate(ip):
    data = requests.get(f'http://ip-api.com/json/{ip}').json()
    print(f"{ip}: {data['city']}, {data['country']} | ISP: {data['isp']}")

geolocate('8.8.8.8')  # Google DNS → Ashburn, Virginia

45 requests/min, no key. Our toolkit

8. ThreatFox — IOC Database

Free indicators of compromise from abuse.ch.

def search_ioc(value):
    resp = requests.post('https://threatfox-api.abuse.ch/api/v1/',
                         json={'query': 'search_ioc', 'search_term': value})
    data = resp.json()
    hits = data.get('data', [])
    print(f"Found {len(hits)} IOCs for {value}")

search_ioc('evil-domain.com')

9. ClinicalTrials.gov — 500K+ Medical Trials

def find_trials(query):
    resp = requests.get('https://clinicaltrials.gov/api/v2/studies', params={
        'query.term': query, 'pageSize': 3, 'format': 'json'
    })
    for s in resp.json().get('studies', []):
        title = s['protocolSection']['identificationModule']['briefTitle']
        status = s['protocolSection']['statusModule']['overallStatus']
        print(f"[{status}] {title[:60]}")

find_trials('cancer immunotherapy')