quicktype is a mature, widely used open-source tool. It has a much longer track record than Live Types and supports far more output languages: TypeScript, Go, Python, Rust, C#, Swift, Kotlin, and others, compared with Live Types' TypeScript + Zod today. If you need types in a language Live Types doesn't support yet, use quicktype.
How they differ
| quicktype | Live Types | |
|---|---|---|
| Output languages | Many (TS, Go, Python, Rust, C#, Swift, Kotlin, more) | TypeScript + Zod (more planned) |
| Runtime validators | Language-dependent | Zod, generated alongside the type |
| Remembers a prior result | No. One-shot: generate and done | Yes. Snapshot saved locally or exported as a file |
| Detects the shape changed later | No | Yes. Diff a new sample against the saved snapshot |
| Shareable input link | No | Yes. Samples mirror into the URL, no backend |
| Runs anywhere without setup | CLI install, or the web playground | Browser only, nothing to install |
What a one-shot generator doesn't cover
Generating a type from a JSON sample is a solved problem. quicktype solved it years ago and does it well. The part a one-shot generator doesn't handle is six weeks later, when the API you generated types against adds a field or quietly makes one nullable, and nothing tells you.
Live Types keeps the inferred shape as a snapshot, either in the browser or as an exported file you commit. A new sample can be diffed against it, so the change shows up in the diff instead of as a runtime surprise in production. That's a narrower problem than generating a type. quicktype doesn't attempt it, because it's built as a generator and doesn't keep anything between runs.
Multi-sample handling
Live Types merges every sample you paste into one shape. A field present in some samples and missing from others becomes optional. A field that's sometimes a string and sometimes a number becomes a union. The result comes from what varied across your inputs, not a guess from one example.
Whether quicktype's multi-sample handling matches this in every case is something to check in quicktype's own docs before you rely on either tool for a field you care about. It's a fast-moving project, and any claim this page made about its internals could be out of date by the time you read it.
Pick quicktype if
- You need a language Live Types doesn't generate yet.
- You want a one-shot type from a single response and nothing more.
- You're already scripting it into a build step via the CLI.
Pick Live Types if
- You're targeting TypeScript + Zod.
- You have several response samples and want the merged shape, not a guess from one.
- You want to find out later if the API's shape drifts from what you generated against.