Schelo

Install

Add the package, then Zod if it is not already in your project (peer dependency).

npm install schelo zod

npm install schelo zod

npx schelo init

npx schelo init

How it works

You describe which URLs matter and what JSON should look like; the interceptor does the rest at runtime.

• Register routes

  List endpoints in routes with optional request and response Zod schemas.

• Traffic is watched

  Your app uses fetch; matching calls are checked automatically.

• Match & validate

  When the URL matches a pattern like GET /api/users/:id, JSON is validated against your schema.

• Clear feedback

  Failures: boxed console output with route and fields. Success: nothing printed.

Create the config

createInterceptor + a routes map (METHOD /path keys, optional Zod request / response). Failures go to the console only—no log buffer. Details: Config & API. Enable via Next.js or React.

import { createInterceptor } from "schelo";
import { z } from "zod";

export const interceptor = createInterceptor({
  mode: "warn",
  routes: {
    "GET /api/health": {
      response: z.object({ status: z.literal("ok") }),
    },
    "POST /api/items": {
      request: z.object({ title: z.string() }),
      response: z.object({ id: z.string(), title: z.string() }),
    },
  },
});

import { createInterceptor } from "schelo";
import { z } from "zod";

export const interceptor = createInterceptor({
  mode: "warn",
  routes: {
    "GET /api/health": {
      response: z.object({ status: z.literal("ok") }),
    },
    "POST /api/items": {
      request: z.object({ title: z.string() }),
      response: z.object({ id: z.string(), title: z.string() }),
    },
  },
});