Blog
Notes from the team behind Persimmon — engineering deep-dives, design notes, and the occasional opinion on how online tools should be built.
PrivacyApril 25, 2026·8 min read
Why every PDF tool on Persimmon runs in your browser
When you upload a PDF to a stranger's server, you're handing them every word, signature, and number on the page. Here's why we refused to build it that way.
DesignApril 22, 2026·7 min read
The math behind WCAG contrast checking
Why “4.5:1” is not a slider value, why averaging RGB does not work, and what the new APCA model fixes.
EngineeringApril 18, 2026·9 min read
Choosing v4 UUIDs vs ULIDs vs nanoid
Three identifier formats, three different bets on what matters. Pick the wrong one and the cost shows up months later as either ugly URLs or a slow database.