Clerk

Lightweight, dependency-free, in-memory fake of the Clerk Backend API (v1) over HTTP/JSON. Exercise user, session and organization management with zero cost and zero side effects.

Default port: 4818

Quick start

import { ClerkServer } from "./services/clerk/src/server.js";

const server = new ClerkServer(4818);
await server.start();
// ... run your app/tests ...
await server.stop();

Point the Clerk backend SDK at it via CLERK_API_URL=http://127.0.0.1:4818 and CLERK_SECRET_KEY=sk_test_parlel.

const res = await fetch("http://127.0.0.1:4818/v1/users", {
  method: "POST",
  headers: { Authorization: "Bearer sk_test_parlel", "Content-Type": "application/json" },
  body: JSON.stringify({ email_address: ["jane@parlel.dev"], first_name: "Jane" }),
});
const user = await res.json(); // { id: "user_…", object: "user", email_addresses: [...] }

Implemented operations

All /v1 routes require Authorization: Bearer sk_test_… (any non-empty bearer is accepted). State is in-memory and ephemeral; ids are deterministic.

Users

GET /v1/users — list users.
POST /v1/users — create a user → { id:"user_…", object:"user", email_addresses:[], first_name, … }.
GET /v1/users/:id — retrieve.
PATCH /v1/users/:id — update first/last name and metadata.
DELETE /v1/users/:id — delete → { object:"user", id, deleted:true }.

Sessions

POST /v1/sessions/:id/verify — verify (creates+activates if unknown) → { object:"session", status:"active", … }.
GET /v1/sessions — list sessions.
GET /v1/sessions/:id — retrieve.

Organizations

GET /v1/organizations — list ({ data:[], total_count }).
POST /v1/organizations — create → { object:"organization", id:"org_…", name, slug, … }.

Service & control endpoints (parlel extensions)

GET / — service metadata.
GET /health — { status: "ok" }.
POST /__parlel/reset — reset all in-memory state.
OPTIONS * — CORS preflight (204).

Access via MCP / preview URL

Clerk is an HTTP service, so in a sandbox it is exposed at its own Daytona preview URL (not via MCP parlel_execute). Use the preview URL from the Connect panel with the preview token header, and set CLERK_API_URL to that host.

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.

Feature	Status
Users CRUD	✅ Supported
Sessions verify / list / get	✅ Supported
Organizations create / list	✅ Supported
Deterministic `user_…` / `org_…` ids	✅ Supported
Real JWT session token verification / networkless auth	✓ By design — Any non-empty credential is accepted — no real secrets needed
Email/SMS delivery, OTP, magic links	✓ By design — Not delivered
Org memberships / invitations / roles	◐ Partial (org create/list only)
Secret key validity / scope enforcement	✓ By design — Any non-empty credential is accepted — no real secrets needed

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.

CLERK_SECRET_KEY=sk_test_parlel
CLERK_API_URL=http://parlel-bridge:4818
CLERK_PUBLISHABLE_KEY=pk_test_parlel