Playground
Small tools, built along the way.
Calculators, converters and helpers I build for myself and share here. They run in your browser, and each one tells you what it is for, how it calculates and where its limits are.
Tools
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Networking
Subnet Calculator (IPv4)
Network address, broadcast, host range and subnets from an address and prefix, with binary view.
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Networking
What Is My IP Address?
The public IPv4 or IPv6 address your device uses right now – with what it means and when it is not your own.
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Electrical
Ohm’s Law & Power Calculator
Enter two of voltage, current, resistance and power, get the other two with the working shown.
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Electrical
Resistor Colour Code
Read 4, 5 and 6-band resistors – or get the bands and nearest E-series value for any resistance.
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Electrical
Electricity Cost Calculator
Energy use and running cost of a device per day, month and year – with standby and average prices for 42 countries.
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Electrical
Battery Runtime Calculator
How long a power bank or leisure battery lasts – or how big it must be – in mAh, Ah or Wh.
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Fun & random
Wheel Spinner
Put your own entries on the wheel and spin – fair randomness, history and a link to share.
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Fun & random
Random Number Generator
Random numbers in any range, dice from d4 to d100, coin flips or a shuffled list.
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Fun & random
Random Name Picker
Pick one person, share out tasks fairly, make teams or draw the order.
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Fun & random
Name Generator
Team names, elvish or dwarvish fantasy names and gamertags – ten ideas per click.
xmoo.app started in German, and most tools are only available in German so far – among them e-invoice tools for XRechnung and ZUGFeRD and more electrical calculators. English versions follow one by one. Until then, the German home page lists everything.
APIs for developers
The engines behind the e-invoice tools and the cable sizing calculator are also available as REST APIs for your own software – in English, hosted in the EU: xmoo APIs.