Why You Should Stop Writing TypeScript Interfaces Manually

I've Typed Out Thousands of Interfaces. It Was All Wasted Time.

After 6 years of TypeScript development, I calculated that I've probably spent 200+ hours manually transcribing JSON responses into interface definitions. Two hundred hours of copying field names, guessing types, and writing nested interfaces.

That's over 8 full days of my life. Gone. Typing boilerplate that a machine could generate in milliseconds.

According to GitHub's Octoverse reports, TypeScript is now the 4th most-used language on the platform. And according to the State of JS survey, over 85% of developers who try TypeScript continue using it. The type safety is undeniably valuable—but the type writing? Pure tedium.

The "any" Epidemic

When developers get frustrated with typing, they do something dangerous:

const data: any = await response.json();

They promise to fix it later. They never do.

According to TypeScript team discussions and community analysis, codebases with high any usage lose most of the benefits of TypeScript—you're paying the compilation cost without getting the safety guarantees.

I've seen production bugs that would have been caught at compile time if someone had just typed the API response properly. Instead, they used any and the bug reached users.

The Workflow That Changed Everything

After wasting years on manual typing, I automated my entire workflow:

1. Hit an API endpoint (Postman, curl, browser devtools)
2. Copy the JSON response
3. Paste into the Type Converter
4. Get a perfect interface definition in seconds

That's it. What used to take 10-15 minutes of careful transcription now takes 10 seconds.

Beyond TypeScript: Runtime Validation with Zod

Here's something many developers don't think about: TypeScript interfaces only exist at compile time. They evaporate when the code runs.

If your API sends malformed data, TypeScript won't catch it. The request will succeed, your type will be wrong, and you'll get mysterious runtime errors.

This is why runtime validation libraries like Zod have exploded in popularity. According to npm download statistics, Zod has grown from ~100k weekly downloads in 2021 to over 7 million in 2024.

Our type converter generates Zod schemas automatically. You get:

• Compile-time type safety from TypeScript
• Runtime validation from Zod
• Zero manual typing

Support for Multiple Languages

It's not just TypeScript. The tool handles:

Go: Generates properly tagged structs for JSON unmarshalling Python: Creates Pydantic models for FastAPI and Django Java: Outputs classes with Jackson annotations C#: Produces classes ready for System.Text.Json

Common Edge Cases the Tool Handles

After building this converter and testing it with hundreds of real-world API responses, here are the tricky cases it handles automatically:

Nullable fields: Detects when values can be null and types them appropriately Union types: When a field contains different types, it creates proper unions Nested objects: Generates separate interface definitions for nested structures Arrays: Correctly types array contents including homogeneous and heterogeneous arrays Date strings: Optionally converts ISO date strings to Date types

Stop Trading Brainpower for Boilerplate

Your time has value. Every minute spent transcribing JSON into interfaces is a minute not spent on actual logic.

The Type Converter runs in your browser, handles your production data privately, and generates code in seconds. Use it.