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Dummy TypeScript Interface Generator

Used by developers, writers, and creators worldwide.

A dummy TypeScript interface generator cuts the busywork of hand-writing placeholder types before your real models exist. Paste the output straight into any `.ts` or `.tsx` file and get a syntactically valid interface with primitive types, arrays, Dates, and Records — ready to wire into components or tests without a finalized schema in sight. You control two things: the number of fields (useful for matching the rough size of your actual model) and whether optional fields are included. Toggling optionals on adds the `?` syntax and produces more realistic shapes for testing partial or nullable payloads. Both settings make the output immediately usable rather than just decorative scaffolding.

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How to use

  1. Choose your options above
  2. Click Generate
  3. Copy your result

Detailed instructions

  1. Set the Number of Fields slider to however many properties you want the interface to contain.
  2. Choose whether to include optional fields — select 'yes' for realistic partial shapes, 'no' for fully required interfaces.
  3. Click Generate to produce a random, syntactically correct TypeScript interface.
  4. Copy the output and paste it into your `.ts` or `.tsx` file as a starting scaffold.
  5. Rename fields to match your domain and adjust any types that don't fit your data model.

Use Cases

  • •Scaffolding typed API response shapes in a Next.js project before the backend contract is finalized
  • •Generating Jest or Vitest fixture types that cover both required and optional fields in one pass
  • •Drafting a Zustand store interface quickly, then renaming fields to match your actual domain
  • •Creating realistic prop types for Storybook stories when the real component model isn't ready yet
  • •Producing varied interface examples for a TypeScript tutorial or dev blog post without writing them by hand

Tips

  • →Generate with optional fields enabled when prototyping PATCH endpoints — those payloads almost always have partial shapes.
  • →Run the generator two or three times and merge the best field names from each result rather than accepting the first output as final.
  • →If you need a nested type, generate two interfaces separately and replace one field's type with the second interface name.
  • →For Jest fixtures, generate an interface with 8 fields, then use it to type a const mock object — the compiler will flag any fields you forget to populate.
  • →When teaching TypeScript, generate a fresh interface each lesson to keep examples varied and prevent students from memorising a single example.
  • →Disable optional fields when generating a base interface, then re-enable them to generate a matching partial type — useful for update/edit form models.

FAQ

how do optional fields work in a TypeScript interface

A `?` after the field name means the property may or may not exist on the object — TypeScript treats it as `string | undefined` rather than requiring it. This is common in PATCH request bodies, partial state slices, or any shape where some properties are conditionally present. Toggle the optional fields setting on to see this syntax in the generated output.

can I use a generated TypeScript interface directly in my codebase

Yes, as scaffolding. The output is valid TypeScript and drops into any `.ts` or `.tsx` file without syntax errors. Rename the fields to match your domain and swap out any types that don't fit — the structure is correct, the names are placeholders.

typescript interface vs type alias — which should I use

For plain object shapes, both work and are largely interchangeable. Interfaces support declaration merging (useful in library code), while type aliases handle unions, intersections, and mapped types. For most app-level models — API responses, form data, state slices — either choice is fine and mostly a team convention.