I build legal technology, at Fifty Six Law and independently, and I research characters that pass for one another. I write about the work at paultendo.github.io.
confusable-vision is the world's first font-by-font confusables dataset: which Unicode characters look alike, measured from the outlines of 322 fonts at the size people read them. Its data is used in Mozilla's add-on name checks, disarm and SilverSpeak.
namespace-guard checks whether a username or slug is really free: across your users, organisations and reserved routes, and against names made to pass for one you protect, like rnicrosoft. On npm, with no dependencies. agent-sanitizer uses it to fold lookalike characters in AI agents' tool calls back to ASCII.
d0ma1n finds the lookalikes of a domain that someone has already registered, and what each one is set up to do.
skills teach Claude Code and Codex to use namespace-guard and d0ma1n when a task calls for them. Add them with claude plugin marketplace add paultendo/skills.
tothepenny turns bank statement PDFs into a spreadsheet, checked against the balances the bank printed. It runs in your browser, so the statements stay on your computer.
agent-notify sends a desktop notification when Codex, Claude Code or Gemini CLI finishes, needs an approval or hits an error.