MockHero vs Faker.js: Which Test Data Tool Should You Use?

TL;DR

Faker.js is a great local library for sprinkling random values into tests. MockHero is an API that returns entire relational datasets in one call — with foreign keys, deterministic seeds, and JSON/CSV/SQL output ready to insert into your database. Use Faker for inline fixtures; use MockHero when you need a dataset, not a field.

At a Glance

• Faker.js — npm library, returns one value at a time, you build the loop.
• MockHero — single API call returns the whole dataset with foreign-key integrity.
• Faker.js — JavaScript only.
• MockHero — language-agnostic (any HTTP client works).
• Faker.js — you write the schema glue code.
• MockHero — declare tables and ref fields; relations are automatic.

The Same Task, Both Ways

Goal: 20 users and 100 posts, each post belongs to a user.

Faker.js

import { faker } from "@faker-js/faker";

const users = Array.from({ length: 20 }, () => ({
  id: faker.string.uuid(),
  name: faker.person.fullName(),
  email: faker.internet.email(),
}));

const posts = Array.from({ length: 100 }, () => ({
  id: faker.string.uuid(),
  user_id: faker.helpers.arrayElement(users).id,
  title: faker.lorem.sentence(),
  body: faker.lorem.paragraphs(2),
}));

MockHero

curl -X POST https://api.mockhero.dev/api/v1/generate \
  -H "x-api-key: mh_your_api_key" \
  -d '{
  "tables": [
    { "name": "users", "count": 20, "fields": [
      { "name": "id", "type": "uuid" },
      { "name": "name", "type": "full_name" },
      { "name": "email", "type": "email" }
    ]},
    { "name": "posts", "count": 100, "fields": [
      { "name": "id", "type": "uuid" },
      { "name": "user_id", "type": "ref", "ref": "users.id" },
      { "name": "title", "type": "sentence" },
      { "name": "body", "type": "paragraphs" }
    ]}
  ]
}'

Where MockHero Wins

• Relational data is declarative. ref fields mean no hand-wiring foreign keys.
• Output formats. Return JSON, CSV, or ready-to-run SQL INSERT statements.
• Deterministic seeds. Pass seed and CI gets the same dataset every time.
• Language-agnostic. Python, Go, Ruby, Rust — any HTTP client works.
• Zero maintenance. No package upgrades, no transitive vulns.

Where Faker.js Wins

• Offline unit tests that don't touch the network.
• Generating a single random value inline.
• Projects with no budget for any paid tool (though MockHero has a free tier).

Combine Them

Many teams use both: Faker.js in unit tests for single-value stubs, MockHero for full seed datasets and staging environments. The two aren't mutually exclusive.

Get Started

Grab a free MockHero API key and generate a relational dataset in your first minute.