How do I mock the Resend API locally?

Install stunt, add a one-service block to stunt.yaml (adapter: embedded:resend-style), and run stunt up. You get a local, stateful stand-in for Resend API 1.0.0 — 6 routes over rest — with no remote account, no network, and no bills.

Is the Resend API mock data synthetic?

Yes — entirely. The adapter returns generated data only; stunt's adapter lint rejects real-looking secrets and PII at build time. It simulates the shape and behavior of Resend API (routes, status codes, pagination, webhooks), never real records.

← all adapters

resend-style

simulates Resend API 1.0.0

restadapter v0.1.06 routes

verification

SDKverified with resend-node 6.22.0 (floor)· surface 6 · not implemented 6 · differs 3

use it

# add to stunt.yaml
services:
  resend:
    adapter: embedded:resend-style

# then
$ stunt up

The embedded: source extracts this adapter from the binary — no git clone, fully offline.

how to mock the Resend API locally

Install stunt, paste the service block above into stunt.yaml, run stunt up — then point your client at localhost instead of Resend API. It works offline, keeps state across requests and restarts, and every response is synthetic: the route shapes, status codes, pagination, and webhook delivery follow the real Resend API 1.0.0 surface — the data is fake, the behavior is real.

backing stores

emails

api surface (6)

generated from the adapter manifest — exactly what boots, nothing more · covers 10% of the real API's 20 routes (derived from sdk resend-node @ 6.22.0 (floor))

6 routes

POST/emails

GET/emails

GET/emails/{id}

POST/webhooks

GET/webhooks

DELETE/webhooks/{id}

SDK-verified behaviors (4)

✓emails.send mints a re_* id
✓emails.get round-trips the message
✓emails.list includes it
✓delivery state derives on read (sent -> delivered)

Not implemented (6)

No domains surface (create, list, verify, delete)
No API keys management (/api-keys)
No batch send (POST /emails/batch)
No scheduled sends (schedule, cancel schedule)
No audiences or contacts
No broadcasts or tags

Differs from the real API (3)

Delivery derives on read: sent at +1s, delivered at +3s — fixed, not async
simulate_fail: true in POST /emails forces bounced terminal (simulator extension)
Webhook events fire exactly once on the first deriving read, not on real delivery

full scorecard →

want more of the Resend API surface? adapters are YAML + Starlark — the authoring guide covers adding routes, fixtures, and state machines. Open an issue for anything big first, or just file a PR — merged routes ship in the next release.