Read docs Updated 2026-06-16
What is Userstack?
Userstack is an API service that accepts User-Agent strings and returns corresponding data in JSON format.
It is useful for developers and applications that need to identify client details from User-Agent headers.
What you can build with Userstack
Device Detection for Analytics
Parse incoming User-Agent headers to record exact browser versions, operating systems, and device types for building accurate traffic and engagement dashboards.
Adaptive Content Serving
Detect client platform details in real time to deliver device-specific assets such as mobile layouts, retina images, or feature-polyfills.
Bot and Crawler Filtering
Identify known bots, outdated browsers, or suspicious User-Agent patterns to reduce spam, scraping, and fraud in web applications.
Get started with Userstack
- 1Sign up and create an OAuth application to obtain client credentials
- 2Review the endpoint reference and supported lookup parameters
- 3Implement OAuth 2.0 token acquisition in your backend code
- 4Make an authenticated HTTPS request containing the User-Agent string
- 5Parse the returned JSON object for structured device, browser, and OS fields
Userstack: pros & cons
Pros
- +OAuth-based authentication for secure access
- +Consistent JSON output that is easy to integrate
- +HTTPS-only transport protects data in transit
- +Specialized focus on accurate User-Agent parsing
Cons
- –Requires an outbound network call for every lookup
- –Usage volume may be limited by subscription tier
- –Accuracy depends on the provider's device database coverage
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Frequently asked questions
A JSON API that securely parses User-Agent strings to return structured information about browsers, operating systems, and devices.
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