Tutorials

Parsing User Agents at Scale: A Practical Guide

ApiCrate Team
api python tutorial user-agent

Every HTTP request carries a user agent string — a fingerprint of the browser, OS, and device making the request. Parsing these strings correctly is surprisingly hard.

Why Parse User Agents?

User agent parsing powers:

  • Analytics dashboards — know which browsers and devices your users prefer
  • Feature flags — serve different experiences to mobile vs desktop
  • Bot detection — identify crawlers, scrapers, and automated tools
  • Compatibility checks — warn users on unsupported browsers

Quick Start

A single API call gives you structured data from any UA string:

curl -X POST https://api.apicrate.io/api/v1/ua \
  -H "X-API-Key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ua": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"}'

Response:

{
  "status": "ok",
  "data": {
    "client": {
      "type": "browser",
      "name": "Chrome",
      "version": "120.0.0.0"
    },
    "os": {
      "name": "Mac",
      "version": "10.15.7",
      "family": "Mac"
    },
    "device": {
      "type": "desktop"
    }
  }
}

Bulk Parsing

Need to process thousands of UAs? Use the bulk endpoint:

import requests

user_agents = [
    "Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X)...",
    "Mozilla/5.0 (Linux; Android 14; Pixel 8)...",
    "Googlebot/2.1 (+http://www.google.com/bot.html)",
]

resp = requests.post(
    "https://api.apicrate.io/api/v1/ua/bulk",
    headers={"X-API-Key": "YOUR_KEY"},
    json={"ua_list": [{"ua": ua} for ua in user_agents]},
)

for result in resp.json()["data"]:
    client = result["client"]["name"] if result["client"] else "Unknown"
    os_name = result["os"]["name"] if result["os"] else "N/A"
    print(f"{client} on {os_name}")

The bulk endpoint processes up to 100 user agents per request — much faster than individual calls.

Field Filtering

Only need the browser name? Use the fields parameter to reduce payload size:

curl -X POST "https://api.apicrate.io/api/v1/ua?fields=client,os" \
  -H "X-API-Key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ua": "..."}'

This returns only the fields you asked for, reducing response size and improving parsing speed.

What's Next?

In the next post, we'll cover secure hashing — from quick MD5 checksums to production-grade password hashing with argon2.

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