🛠️ Developer Tools

Inside the 300-Line JSON-to-TypeScript Engine That Outsmarts Quicktype

Staring at raw JSON from a new API? This 300-line vanilla JS beast infers TypeScript types across samples, spots optionals, and spits type guards. No more guesswork.

theAIcatchup Apr 11, 2026 3 min read
Live demo of JSON-to-TypeScript generator outputting merged interfaces

⚡ Key Takeaways

  • Tiny AST + refs enable named nests and easy merging 𝕏
  • Multi-sample optionals emerge naturally from merge logic 𝕏
  • Dual rendering (interfaces + guards) from one type tree 𝕏
Published by

theAIcatchup

Community-driven. Code-first.

#JSON to TypeScript #TypeScript #TypeScript inference #type guards #type inference #vanilla JavaScript #vanilla js

Worth sharing?

Get the best Open Source stories of the week in your inbox — no noise, no spam.

Originally reported by Dev.to

Related Stories

📬

Stay in the loop

The week's most important stories from theAIcatchup, delivered once a week.

No spam. Unsubscribe any time.