Official @wthek Extension – Zod Transformer for `http-error-kit`

Convert Zod validation errors into structured http-error-kit errors — framework-free

Built for projects using http-error-kit, this utility transforms native Zod validation errors into rich, consistent BadRequestError responses.

💡 What the HEK?! Tired of parsing raw Zod errors? Let @wthek/zod-transformer convert them into usable, standardized errors — no framework needed.

GitHub Workflow Status npms.io (final) npm npm bundle size (version) NPM Type Definitions

Features

Framework-Agnostic – Works with any HTTP server: Express, Fastify, Hapi, Koa, NestJS, etc
Preserves Zod Issues – Keeps all raw ZodIssue[] data for later formatting
Handles ZodError gracefully – Converts it to HttpError.BadRequest
Formatter-Friendly – Customize your output using KitHttpErrorConfig.configureFormatter
Plug-and-play logic – One function to drop in wherever you handle errors
Composable – Can be used alongside @wthek/*-middleware extension

Installation

npm install @wthek/zod-transformer

Usage

Add Middleware Just Before Starting the Server

Use KitZodTransformer in your error pipeline before global error-handling middleware like @wthek/express-middleware or @wthek/fastify-middleware.

This ensures Zod validation errors are transformed into http-error-kit errors early, allowing WTHek or any other middlewares to handle them cleanly.

import { KitZodTransformer } from "@wthek/zod-transformer";
import { z } from "zod";

try {
    const schema = z.object({
        name: z.string(),
        age: z.number().min(18),
    });

    schema.parse({ name: "Hek", age: 14 }); // Will fail
} catch (err) {
    throw KitZodTransformer(err); // Converts to HttpError.BadRequest(...)
}

With Express/Fastify/NestJS

Use the transformer early in your error handling pipeline — before applying framework-specific middleware like:

This ensures Zod validation errors are transformed into http-error-kit errors early, allowing WTHek or any other middlewares to handle them cleanly.

Optional: Custom Formatting with `KitHttpErrorConfig`

To define how your error responses look in production:

import { KitHttpErrorConfig } from "http-error-kit";

KitHttpErrorConfig.configureFormatter(
    (statusCode, message, details, ...args) => ({
        code: statusCode,
        msg: message,
        extra: details,
        traceId: args[0] || "0fcb44cb-4f09-4900-8c4f-73ddd37ffe0a",
    })
);


// Response
{
    "code": 400,
    "msg": "Zod validation failed",
    "extra": {
        "issues": [
            {
                "code": "too_small",
                "minimum": 18,
                "type": "number",
                "inclusive": true,
                "exact": false,
                "message": "Number must be greater than or equal to 18",
                "path": ["age"]
            }
        ]
    },
    "traceId": "0fcb44cb-4f09-4900-8c4f-73ddd37ffe0a"
}

Explore More WTHek Extensions

The WTHek ecosystem continues to grow with new extensions to simplify error handling across various frameworks and libraries. Stay updated with the latest tools that integrate seamlessly with http-error-kit.

Check out the official list of extensions: Official Extensions List

People

The original author of the project is Himanshu Bansal

Donations

This is all voluntary work, so if you want to support my efforts you can

You can also use the following:

License

@wthek/zod-transformer project is open-sourced software licensed under the MIT license by Himanshu Bansal.

Official @wthek Extension – Zod Transformer for http-error-kit