What's the Most Underrated Free API You've Ever Used?

#javascript #webdev #api #discuss

I've spent the last year building web scrapers and data pipelines, and I keep discovering free APIs that blow my mind.

Here are my top 3 most underrated ones:

1. npm Registry API

Did you know you can query any npm package without authentication?

const res = await fetch('https://registry.npmjs.org/express');
const pkg = await res.json();
console.log(pkg.description); // Fast, unopinionated web framework
console.log(Object.keys(pkg.versions).length); // 270+ versions
console.log(pkg.maintainers); // Current maintainers list

No API key. No rate limits (within reason). Returns full package metadata, download counts, dependency trees — everything.

Why it's underrated: Most devs only use npm via CLI. But the API lets you build security scanners, dependency analyzers, and package comparison tools.

2. Wayback Machine API

The Internet Archive has a free API that lets you check how ANY website looked at any point in history:

import requests

url = "http://archive.org/wayback/available?url=google.com&timestamp=20000101"
data = requests.get(url).json()
print(data["archived_snapshots"]["closest"]["url"])
# Returns a link to Google's homepage from 2000!

Why it's underrated: Perfect for competitive analysis, detecting when competitors changed pricing, or just nostalgia.

3. Have I Been Pwned API

Troy Hunt's breach database lets you check if an email was in a data breach — programmatically:

import hashlib, requests

password = "mypassword123"
sha1 = hashlib.sha1(password.encode()).hexdigest().upper()
prefix, suffix = sha1[:5], sha1[5:]

res = requests.get(f"https://api.pwnedpasswords.com/range/{prefix}")
count = [line.split(":")[1] for line in res.text.splitlines() if line.startswith(suffix)]
print(f"Found in {count[0]} breaches!" if count else "Safe!")