API Mocker

Intelligent API mocking & fake-data microservice: turn a JSON Schema into realistic example instances (mockFromSchema), stand up a mock REST endpoint response envelope with N seeded rows...

api-mocker

Intelligent API mocking & fake-data microservice. Turn a JSON Schema or a { field: type } spec into realistic example data, mock REST response envelopes, seed datasets/fixtures, and canonical HTTP status scenarios (200 / 4xx / 5xx bodies). Deterministic and seedable — great for prototyping frontends, stubbing backends, contract tests, and demo data.

Tools

Tool	Purpose
`mockFromSchema`	JSON Schema → one realistic example instance (or N with `count`). Optional LLM enrichment via `options.enrich`.
`mockEndpoint`	A full mock REST response: N seeded rows from a schema wrapped with pagination `meta` + self link.
`fakeRecord`	One fake record from a `{ field: type }` spec.
`generateDataset`	A whole seed dataset / fixture table (rows + summary; optional CSV via `options.format:'csv'`).
`statusScenarios`	Canonical HTTP status responses with realistic JSON bodies for error-handling tests.

Field-type tokens (for `fields`)

name, firstName, lastName, username, email, phone, uuid, id, url, image, ip, city, address, company, country, zip, role, status, tag, color, bool, date, datetime, price, currency, int:18-90, float:0-1, enum:admin|user|guest, string:12, sentence, paragraph, slug, word. Nested objects and [elementType, count] arrays are supported.

Usage

import mocker from './index.js';

// Fake records from a spec
mocker.adapters.fakeRecord({ fields: { id: 'uuid', name: 'name', email: 'email', role: 'enum:admin|user', age: 'int:18-90' }, seed: 1 });

// Seed dataset (10 rows) + CSV
mocker.adapters.generateDataset({ fields: { id: 'id', title: 'sentence', price: 'price' }, count: 10, seed: 2, options: { format: 'csv' } });

// Mock endpoint from a JSON Schema
mocker.adapters.mockEndpoint({ schema: { type: 'object', properties: { id: { type: 'integer' }, name: { type: 'string' } }, required: ['id', 'name'] }, count: 3, resource: 'users' });

// HTTP status scenarios
mocker.adapters.statusScenarios({ statuses: [200, 404, 422, 500], resource: 'user' });

Hybrid intelligence

Every tool has a deterministic, offline heuristic core (seedable PRNG + field-type faker). mockFromSchema additionally supports an optional LLM path (options.enrich: true) that asks a reachable model to fill domain-plausible values; if no model is configured/reachable it silently falls back to the heuristic. Results are tagged { mode: 'heuristic' | 'llm' }. No tool ever requires a model.

DRY boundaries

schema owns real JSON-Schema authoring/validation/diff/merge/TS-emit. This pack reuses the

schema→instance concept with a compact self-contained generator; it does not import schema.

lorem owns themed placeholder prose and simple fake people. This pack has its own small faker

banks tuned for API fixtures (roles, statuses, prices, endpoints); it does not import lorem.

Only cross-pack import: ../_shared/llm.js.