This write up on finding arbitrary code execution in ExifTool is interesting both because it's Perl code that I used almost 20 year ago (and is still the best way to do it!), and that it's a great explanation of finding and exploiting vulnerable code.

While researching the different colored bands for bundles of American bank notes, I found this fascinating page about the rules for US currency deposits.

Geography May 9th

I thought my geography was reasonable, but I only hit 52 of the 150 largest countries by area. You get a few tries per country.

The harder version has all 193 members of the UN.

It's been three and a half months since I got PHP CI working on Travis, so of course it's now broken. Github Actions are the new hotness, so I figured out the right magical config to run multi-version CI for PHP over there instead, and it runs much faster too.

IBM Wiring May 3rd

I'd seen the photo a few times, but this is the first I'd read about what was actually being wired up. Turns out it's a semi-mechanical pre-computer for accounting and it's even more interesting than it first looked.

More in the single-serving-webapps-for-games category - a lovely little app for exploring the artifacts in Egg Inc. The web is such a good platrofmr for developing and delivering these micro-apps.

Using machine learning to find the lowercasest and uppercasest letters.

If you're playing Stardew Valley (there's a been a bit of a resurgence with the recent updates), then I recommend using Stardew Profits. I love these little single-serving webapps that do exactly what you need and are served from

This is one of the most perfectly evil things I've seen in a while - edible fake silica gel pouches

Sudoku solving Jan 29th

I don't know how I stumbled into this Sudoku video, but it's extremely relaxing.

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This is the personal website of Cal Henderson, Slack co-founder & CTO.

I give occasional talks, write code and sometimes articles.

» About Cal


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» Building Scalable Wesites (My book)
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» Glitch: Bees!
» Starcraft: Bees #187
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» Kingdom of Loathing: bees (id #29410)
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