Every TypeScript project reaches the same point: you've defined your types, now you need mock data for tests, Storybook stories, or local dev. You end up hand-writing the same boilerplate mockUser
, mockProduct
, mockOrder
objects over and over.
I built FixtureKit to fix that — a free developer tool, not a product pitch.
Paste a TypeScript interface
, type
, or a Zod z.object(...)
schema → get a copy-ready export const mock…
TypeScript fixture.
Try it: https://fixture-kit.vercel.app
Input:
interface Product {
id: string;
name: string;
price: number;
inStock: boolean;
tags: string[];
}
Output:
export const mockProduct: Product = {
id: "f47ac10b-58cc-4372-a567-0e02b2c3d479",
name: "Wireless Keyboard",
price: 49.99,
inStock: true,
tags: ["electronics", "accessories"],
};
What makes it useful
Semantic field inference — it doesn't just fill every string with "value". Field names like email, name, url, price, createdAt map to realistic value pools. Type compatibility is enforced: you won't get an email string on a number field.
Deterministic output — uses a hash of the field name + fixture index. No Math.random(). Same schema always gives the same output. Safe to commit.
No eval, no backend — Zod schemas parsed with a custom recursive-descent parser. TypeScript schemas use the TypeScript compiler API. Everything runs in the browser.
Generate up to 5 fixtures at once — useful for seeding UI components or table/list test cases.
Supported input
TypeScript: interface, type, arrays, nested objects, optional fields, unions, literal types
Zod: z.object, z.string, z.number, z.boolean, z.array, z.enum, z.union, z.literal, .optional(), .nullable(), nested z.object
Advanced features (generics, utility types, .refine, .transform) are out of scope and return a clear error.
Tech
React 18 · TypeScript 5 · Vite · TypeScript compiler API (in-browser)
Source
https://github.com/Wasef-Hussain/FixtureKit
Feedback welcome — especially on schema shapes I haven't handled well.