quicktype is a mature, widely-used, open-source tool with a much longer track record than Living Types and support for far more output languages — TypeScript, Go, Python, Rust, C#, Swift, Kotlin, and others, against Living Types' TypeScript + Zod today. If you need a type generated for a language Living Types doesn't support yet, quicktype is the right tool and there's no honest way to spin that as a Living Types win.
Where the actual difference is
| quicktype | Living 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 |
The actual gap this fills
Generating a type from a JSON sample is a solved problem — quicktype solved it years ago and does it well. What isn't solved by a one-shot generator is what happens six weeks later when the API you generated types against adds a field, or quietly makes a field nullable, and nothing tells you. Living Types keeps the inferred shape as a snapshot — in the browser or exported as a file you commit — so a new sample can be diffed against it and the actual change shows up as a change, not a runtime surprise in production. That's a narrower problem than "generate a type," and it's the one part of this that quicktype doesn't attempt, because it isn't trying to be a persistence layer — it's a generator.
Multi-sample handling
Living Types merges every sample you paste into one shape — a field present in some samples and missing in others becomes optional, a field that's sometimes a string and sometimes a number becomes a union, based on what actually varied across the real inputs rather than a guess from one example. Whether quicktype's current multi-sample handling matches this in every case is worth checking directly on quicktype's own docs before relying on either tool for a field you care about — it's a fast-moving project and this page isn't the place to make a claim about its internals that might already be out of date by the time you're reading it.
Pick quicktype if
- You need a language Living 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 Living Types if
- You're specifically targeting TypeScript + Zod.
- You have several real response samples and want the merged shape, not a guess from one.
- You want to catch it later if the API's actual shape drifts from what you generated against.