MailerLite

Lightweight, dependency-free, in-memory MailerLite API fake for testing code that uses the real @mailerlite/mailerlite-nodejs SDK (or the language-agnostic MailerLite REST API).

Default port: 4831

Quick start

Start the server:

import { MailerliteServer } from "./services/mailerlite/src/server.js";

const server = new MailerliteServer(4831);
await server.start();
// ... run your app/tests ...
await server.stop();

Point a client at it (Bearer auth):

await fetch("http://127.0.0.1:4831/api/subscribers", {
  method: "POST",
  headers: { Authorization: "Bearer parlel-mailerlite-key", "Content-Type": "application/json" },
  body: JSON.stringify({ email: "subscriber@parlel.dev", fields: { name: "Sub" } }),
});
// => { data: { id, email, status, fields, ... } }

Campaign creation is captured and inspectable via /__parlel/*.

Access via MCP / preview URL

When run under the parlel pool, this service is reachable through the MCP gateway and a preview URL at http://127.0.0.1:4831. Use MAILERLITE_BASE_URL to point clients/agents at it. Captured campaigns live at GET /__parlel/messages.

Implemented operations

All /api/* routes require Bearer auth. Responses use the MailerLite envelopes { data: {...} } and { data: [], meta, links }. State is in-memory and ephemeral.

• GET /api/subscribers — list subscribers.
• POST /api/subscribers — create or upsert a subscriber (email required).
• GET /api/subscribers/:id — get a subscriber by id or email.
• PUT /api/subscribers/:id — update a subscriber.
• DELETE /api/subscribers/:id — delete a subscriber (204).
• GET /api/groups — list groups.
• POST /api/groups — create a group (name required).
• POST /api/campaigns — create a campaign (name + type required); captured.
• GET /api/campaigns — list campaigns.
• GET /api/account — account info.

Service & inspection operations (parlel extensions)

• GET / — service metadata.
• GET /health — health check ({ status: "ok" }).
• POST /__parlel/reset — reset all in-memory state.
• GET /__parlel/messages — list captured campaigns ({ messages, count }).
• GET /__parlel/messages/:id — fetch a single captured campaign.
• DELETE /__parlel/messages — clear only the captured mailbox.

Surface coverage

This emulator faithfully replicates the API surface most application code and agents exercise. Anything below the supported lines is either an intentional design choice for a fast, zero-cost local emulator (✓ By design) or a candidate for a future release (⟳ Roadmap) — never a silent inaccuracy.

Legend: ✅ fully supported · ◐ accepted (stored, not strictly enforced) · ✓ by design · ⟳ on the roadmap.

Error shapes

Errors use the MailerLite envelope { "message": "...", "errors": { field: [..] } }.

Manifest

See services/mailerlite/manifest.json:

• name: mailerlite, image: parlel/mailerlite:1.0
• port: 4831, protocol: http, healthcheck: /health, startup ≈ 100ms
• env: MAILERLITE_API_KEY, MAILERLITE_BASE_URL

Configuration — test.env

Copy these into your test.env (used by the bridge sidecar flow). Tokens are Parlel's seeded test credentials — any non-empty value is accepted by the emulator, so you rarely need to change them. Swap in real credentials only when pointing at the live service in prod.env.

MAILERLITE_API_KEY=parlel-mailerlite-key
MAILERLITE_BASE_URL=http://parlel-bridge:4831