User Agent Tester

Parse any user agent into browser, engine, OS and device.

Free
No signup
Nothing uploaded
No watermark

User agent

Yours is filled in already — paste a different one over it to inspect that instead.

How to Check a User Agent String Online

Every browser introduces itself to websites with a user agent string, a long line of text naming the browser, its version and the operating system. Developers need to read these when a bug only happens on one phone, and support staff need them when a customer says 'the site is broken'.

This page fills in your own user agent the moment it opens and breaks it into browser, operating system, rendering engine and device type. Paste any other string over it, from a server log or a bug report, to decode that instead.

No software to install Free Works on any device

Steps to Decode a User Agent

1

1. See your own string

The box already holds the user agent of the browser you are using now, with its details shown underneath.
2

2. Paste another one

Replace the text with a string copied from analytics, an access log or a customer's email to inspect that browser instead.
3

3. Read the four results

Browser with version, operating system, engine and device type appear as separate boxes.
4

4. Watch for bots

If the string calls itself a bot, crawler, spider or Slurp, a red note says so.

Try it now

What Is a User Agent String?

It is the text a browser sends in the User-Agent header with every request. For historical reasons almost every browser claims to be 'Mozilla' and most also mention Safari, so reading one takes pattern matching rather than a simple lookup.

That is also why the result is a best guess. Browsers now freeze or trim parts of the string for privacy, so feature detection is the reliable way for a site to decide what a browser can do.

Why Use IP and Network Calculators?

Subnet masks, CIDR ranges and download times all come down to binary maths that is easy to slip on. These calculators do the sums in the page, so you can plan an address range or check a speed claim with confidence.

“One wrong subnet mask can take a whole office offline.”

Subnets worked out instantly
CIDR ranges made clear
Download times estimated
Browser details revealed

Usable host counts shown
IPv4 and IPv6 conversions
MAC addresses checked
No commands to install

Popular Uses for Subnet Calculators

Network jobs at home and at work often start with one of these sums.

Planning an office network Split an address block into subnets for each floor, team or guest WiFi.
Reading CIDR notation See the first address, last address and host count behind a range like /24.
Download estimates Work out how long a large file will take on a given connection speed.
Speed claims Turn megabits per second into megabytes to see what a plan really delivers.
Device lookups Find the maker of a network card from its MAC address prefix.
Browser checks See your user agent and browser details when a support team asks.
WebSocket tests Connect to a WebSocket endpoint and watch messages go back and forth.
IPv6 planning Convert an IPv4 address into IPv6 form while preparing a migration.

What the User Agent Parser Detects

Main browsers

Edge, Opera, Firefox, Chrome and Safari are recognised, with the version number pulled from the string.

Operating system

Windows, macOS, Android, iOS and Linux, with version numbers where the string includes them.

Rendering engine

Blink, Gecko or WebKit, which is what actually decides how a page's HTML and CSS are drawn.

Device type

Phone, tablet or desktop, worked out from the Mobile, iPad and Tablet markers in the string.

Why Use ToolXkit for User Agent Tester?

Your files stay with you

Everything runs inside your browser. Nothing you open or type is uploaded to a server.

Network Tools for Different Users

Network administrators

Plan subnets, check CIDR ranges and size links for expected bandwidth.

Networking students

Practise subnetting for CCNA and other exams, and check answers quickly.

Developers

Test WebSocket servers, parse user agents and inspect TCP header fields.

IT support staff

Collect browser details and estimate transfer times while helping users.

Small office owners

Understand router settings and IP ranges without calling a technician every time.

Streamers and gamers

Check upload speed, latency and packet loss figures before a stream.

Best Times to Work Out a Subnet

Network calculators help when you are:

Setting up a new router
Studying for a networking exam
Adding a guest WiFi network
Estimating a large upload
Comparing broadband plans
Identifying an unknown device
Moving to IPv6
Debugging a WebSocket connection

Tips for Reading User Agents

Windows 10 and Windows 11 send the same 'Windows NT 10.0' marker, so the result shows them together.
iPads on iPadOS often send a desktop Mac user agent. A tablet may show as Desktop running macOS.
Browsers based on Chrome, such as Samsung Internet or Brave, can appear as Chrome because they carry the same tokens.
When debugging, ask the user to open this page and copy the box. It saves a long exchange about which browser they have.
Bots can fake any user agent. Treat the bot warning as what the string claims, not proof of who sent it.

Frequently Asked Questions

Answers to common questions about this tool.

What is my user agent?

Open this page and look at the box at the top. It is filled in automatically from your browser, and the boxes underneath translate it into the browser name, operating system, engine and device.

Why does Chrome say Mozilla and Safari in its user agent?

Old websites only sent full features to browsers naming Mozilla, and later to WebKit and Safari. Each new browser copied those words to avoid being served a worse page, and the habit stuck.

Can a website see my user agent?

Yes. Your browser sends it with every request, so every site you visit receives it. This page reads it inside your own browser and does not send it anywhere.

Why is my Chrome version shown as 120.0.0.0?

Chrome has reduced its user agent for privacy, replacing the minor version numbers with zeros. The major version is still accurate, but the exact build is no longer in the string.

Can I change my user agent?

Yes. Chrome and Edge let you override it in DevTools under Network conditions, and Firefox and Safari have similar developer options. Paste the new string here to confirm how it will be read.

Is User Agent Tester accurate enough for real network work?

The maths behind addresses and ranges is exact, so the results match what a router expects. Double-check the input, especially the prefix length, since one wrong digit changes the whole range.

Do the calculators scan my network?

No. The subnet and speed calculators only work with the numbers you type in. They send no traffic into your network, and the only tool that connects anywhere is the WebSocket Tester, to the address you enter.

Why is my real download slower than the estimate?

The calculator assumes the full connection speed is available. In practice, WiFi, other devices, server limits and protocol overhead eat into it, so real downloads often take somewhat longer.

Is User Agent Tester free and private?

Yes. It costs nothing and needs no account. What you type stays in your browser and is never sent to ToolXkit, which matters when it describes a real company network.

What is the difference between Mbps and MBps?

Mbps means megabits per second, the unit broadband plans use. MBps means megabytes per second, the unit most download windows show. One byte is eight bits, so 100 Mbps is about 12.5 MBps.

More Internet & Network Tools

Other free tools for the same kind of job.

Browse all tools