Tools · Free & browser-side

Engineering tools

Three small utilities we use every day. All of them run entirely inside your browser — no account, no tracking, and nothing you type or generate is ever sent to a server.

Time zone comparison Random password generator IPv4 subnet calculator

Time zone comparison

Live clocks for the regions we work across, all referenced to UTC. Whether a zone is currently on daylight-saving (summer) time is noted under each entry.

UTC reference—Live

China (Beijing)

Asia/Shanghai

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London

Europe/London

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Frankfurt

Europe/Berlin

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US East (New York)

America/New_York

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US West (Los Angeles)

America/Los_Angeles

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Random password generator

Generated by your browser's cryptographic random number generator (Web Crypto). Every click produces a fresh, unpredictable password that only exists on your screen.

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StrengthVery strong · 130 bits

Entropy: 129.5 bits
Alphabet size: 89

Time to brute-force (average)

Offline attack, 10 billion guesses/s: over 2×10^21 years
Nation-scale attack, 100 trillion guesses/s: over 2×10^17 years

Why this is genuinely random — and how to check for yourself

01Real cryptographic randomness
Passwords come from crypto.getRandomValues(), the operating-system-backed random source your browser also uses to create TLS keys. We never use Math.random(), the clock, or any server-side value.
02No modulo bias
Each character is picked with rejection sampling, so every character in the alphabet is exactly equally likely. Naive implementations using "random % size" quietly favour some characters; this one does not.
03Nothing leaves your browser
This page is a static file. There is no API call when you click Generate, no analytics, no cookies and no history — close the tab and the password is gone unless you copied it.
04Verify it yourself
Open your browser's developer tools (F12) → Network tab, then click Generate: no request is made. Switch your device to airplane mode and it still works. The full source is served to your browser unminified enough to read — nothing is hidden on a server.

IPv4 subnet calculator

Enter an address in CIDR notation, e.g. 10.0.0.5/22. Results update as you type.

IP address in CIDR notation

Quick prefixes

192.168.1.10/24IPv4

Network address: 192.168.1.0/24
Broadcast address: 192.168.1.255
Subnet mask: 255.255.255.0
Wildcard mask: 0.0.0.255
First usable host: 192.168.1.1
Last usable host: 192.168.1.254
Usable hosts: 254
Total addresses: 256
Class: C
Scope: Private (RFC 1918)
Previous subnet: 192.168.0.0/24
Next subnet: 192.168.2.0/24

Binary view

Address11000000.10101000.00000001.00001010

Mask11111111.11111111.11111111.00000000

Highlighted bits are the network portion.