Node.js SDK

@spacepost/node is a zero-dependency, fetch-based client with the same method names and { data, error } return shape as the Resend SDK. It runs on Node 18+, Bun, Deno and edge runtimes.

npm install @spacepost/node
# or: bun add @spacepost/node | pnpm add @spacepost/node | yarn add @spacepost/node

Setup

import { SpacePost } from "@spacepost/node";

// Reads SPACEPOST_API_KEY (and SPACEPOST_BASE_URL) from the environment when no key is passed.
const spacepost = new SpacePost();

// Or configure explicitly, for example in tests or against a self-hosted deployment.
const custom = new SpacePost("sp_live_YOUR_API_KEY", { baseUrl: "https://api.spacepost.dev" });

console.log(spacepost.baseUrl, custom.baseUrl);

Constructor	Environment fallback	Default
`new SpacePost(apiKey)`	`SPACEPOST_API_KEY`	none; throws if missing
`{ baseUrl }`	`SPACEPOST_BASE_URL`	`https://api.spacepost.dev`
`{ fetch }`	n/a	global `fetch` (inject for tests or proxies)
`{ userAgent }`	n/a	`spacepost-node/<version>`

Results and errors

Every method returns a promise of { data, error }. Exactly one is non-null. Methods never throw on API or network errors.

const { data, error } = await spacepost.emails.get(id);
if (error) {
  // error.name        "not_found" | "validation_error" | ...
  // error.message     human readable
  // error.statusCode  HTTP status, or null when the request never got a response
  return;
}
console.log(data.last_event);

(webhooks.verify is the exception: it throws on an invalid signature.)

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost();

const { data, error } = await spacepost.emails.send({
  from: "Acme <hello@acme.com>",
  to: "user@example.com",
  subject: "Hello",
  html: "<p>Hello</p>",
});

if (error) {
  switch (error.name) {
    case "rate_limit_exceeded":
      // wait about a second, then retry with the same idempotency key
      break;
    case "daily_quota_exceeded":
    case "monthly_quota_exceeded":
      // alert someone: you hit a limit
      break;
    case "validation_error":
    case "invalid_from_address":
      // a bug in your request: do not retry
      throw new Error(`${error.name}: ${error.message}`);
    default:
      console.error(error.statusCode, error.name, error.message);
  }
} else {
  console.log(data.id);
}

Request fields can be written in camelCase (replyTo, scheduledAt, contentType, audienceId, tenantId, externalId, dailyLimit) or snake_case; the SDK converts. Responses are returned exactly as the API sends them (snake_case).

Method overview

Namespace	Methods
`emails`	`send`, `get`, `list`, `update`, `cancel`
`batch`	`send`
`domains`	`create`, `get`, `list`, `verify`, `update`, `remove`
`apiKeys`	`create`, `list`, `remove`
`webhooks`	`create`, `get`, `list`, `update`, `remove`, `verify`
`audiences`	`create`, `get`, `list`, `remove`
`contacts`	`create`, `get`, `list`, `update`, `remove`
`broadcasts`	`create`, `get`, `list`, `update`, `remove`, `send`
`suppressions`	`list`, `create`, `remove`
`tenants`	`create`, `get`, `list`, `update`, `remove`, `pause`, `unpause`

emails

send(payload, { idempotencyKey? }), get(id), list({ limit, after, before }), update({ id, scheduledAt }), cancel(id).

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost();

// send
const { data: sent } = await spacepost.emails.send({
  from: "Acme <hello@acme.com>",
  to: "user@example.com",
  subject: "Hello",
  html: "<p>Hello</p>",
  scheduledAt: "in 1 hour",
});

if (sent) {
  // get: includes html/text and last_event
  const { data: email } = await spacepost.emails.get(sent.id);
  console.log(email?.last_event); // "scheduled"

  // update: reschedule
  await spacepost.emails.update({ id: sent.id, scheduledAt: "in 3 hours" });

  // cancel
  await spacepost.emails.cancel(sent.id);
}

// list: cursor pagination, newest first, bodies omitted
const { data: page } = await spacepost.emails.list({ limit: 10 });
if (page?.has_more) {
  const last = page.data[page.data.length - 1]!;
  const { data: older } = await spacepost.emails.list({ limit: 10, after: last.id });
  console.log(older?.data.length);
}

send accepts every field of Send an email, including tenantId for platform mode, plus react for React Email (needs the optional peer dependency @react-email/render; see React Email). Attachment content may be a base64 string, a Buffer or a Uint8Array.

batch

batch.send(emails, { idempotencyKey? }) sends up to 100 emails (each may carry its own tenantId) and resolves to { data: { data: [{ id }] } }. See Batch sending.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

const { data, error } = await spacepost.batch.send(
  [
    { from: "Acme <hello@acme.com>", to: ["a@example.com"], subject: "Hi Ada", html: "<p>Hi Ada</p>" },
    { from: "Acme <hello@acme.com>", to: ["b@example.com"], subject: "Hi Bob", html: "<p>Hi Bob</p>" },
  ],
  { idempotencyKey: "weekly-digest-2026-w43" },
);

if (error) console.error(error);
else console.log(data.data.map((e) => e.id)); // ids in input order

domains

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost();

const { data: domain } = await spacepost.domains.create({ name: "acme.com", customReturnPath: "send" });
if (domain) {
  await spacepost.domains.verify(domain.id);
  const { data: fresh } = await spacepost.domains.get(domain.id); // includes records
  console.log(fresh?.status, fresh?.records);

  await spacepost.domains.update({ id: domain.id, openTracking: true, clickTracking: true });
  await spacepost.domains.remove(domain.id);
}

const { data: all } = await spacepost.domains.list(); // no records in lists
console.log(all?.data.map((d) => d.name));

create({ name, region?, customReturnPath?, tenantId? }), get(id) (with records), list(), verify(id), update({ id, openTracking?, clickTracking? }), remove(id). See Adding and verifying.

apiKeys

create({ name, permission?, domainId? }) returns { id, token }; the token is shown once.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost();

// A key that can only send, and only from one domain.
const { data: key, error } = await spacepost.apiKeys.create({
  name: "worker-prod",
  permission: "sending_access",
  domainId: "0192e1c4-0000-7000-8000-000000000001",
});
if (error) throw new Error(error.message);
console.log(key.token); // sp_live_..., shown only once

const { data: keys } = await spacepost.apiKeys.list();
console.log(keys?.data.map((k) => `${k.name} ${k.prefix}... ${k.permission}`));

await spacepost.apiKeys.remove(key.id);

webhooks

create, get, list, update, remove manage endpoints (Webhooks).

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

const { data: webhook, error } = await spacepost.webhooks.create({
  endpoint: "https://acme.com/webhooks/spacepost",
  events: ["email.delivered", "email.bounced", "email.complained"],
});
if (error) throw new Error(`${error.name}: ${error.message}`);

// Store this secret: you need it to verify signatures. It starts with "whsec_".
console.log(webhook.id, webhook.signing_secret);

verify({ payload, headers, secret }) checks a delivery’s signature and returns the parsed event, or throws. Pass the raw body; headers can be a Headers object or a plain object.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

/** Works as a Bun, Deno, Cloudflare Workers or Next.js route handler. */
export async function POST(request: Request): Promise<Response> {
  const payload = await request.text(); // the RAW body: do not parse it first

  try {
    const event = await spacepost.webhooks.verify({
      payload,
      headers: request.headers,
      secret: process.env.SPACEPOST_WEBHOOK_SECRET!,
    });

    switch (event.type) {
      case "email.bounced":
      case "email.complained":
        console.warn("Stop mailing", event.data.to);
        break;
      case "email.delivered":
        console.log("Delivered", event.data.email_id);
        break;
    }
    return new Response("ok");
  } catch {
    return new Response("invalid signature", { status: 400 });
  }
}

Webhook events are typed. verify returns a WebhookPayload, a union discriminated by type, so narrowing on event.type gives you data.bounce, data.click, data.open, data.failed or data.suppressed. Every event also has data.tenant_id when the email was sent for a tenant. See Event types.

tenants

Platform mode: one tenant per customer you send for, with isolated reputation, a pause switch and an optional daily cap. See the Platform mode guide.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

// One tenant per customer. `externalId` is your own customer id and works anywhere a tenant id does.
const { data: tenant, error } = await spacepost.tenants.create({
  name: "Acme Inc",
  externalId: "cust_123",
  dailyLimit: 500, // optional cap, in recipients per UTC day
});
if (error) throw new Error(`${error.name}: ${error.message}`);
console.log(tenant.id, tenant.status); // "active"

// Optional: give the tenant its own sending domain. Mail from it is attributed to the tenant automatically.
const { data: domain } = await spacepost.domains.create({ name: "mail.acme-inc.com", tenantId: "cust_123" });
console.log(domain?.tenant_id === tenant.id); // true

create({ name, externalId?, dailyLimit? }), get(idOrExternalId), list({ limit, after, before }), update({ id, name?, externalId?, dailyLimit? }) (dailyLimit: null removes the cap), remove(idOrExternalId) (422 while the tenant has domains), pause({ id, reason? }) (or pause(id)) and unpause(idOrExternalId) (403 for reputation pauses unless your team is trusted). Anywhere an id is expected you can pass your external_id.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

const { data: page } = await spacepost.tenants.list({ limit: 20 });
for (const t of page?.data ?? []) console.log(t.name, t.external_id, t.status, t.paused_reason);

await spacepost.tenants.get("cust_123"); // by external_id or our id
await spacepost.tenants.update({ id: "cust_123", dailyLimit: 1000 }); // dailyLimit: null removes the cap

await spacepost.tenants.pause({ id: "cust_123", reason: "Investigating spam reports" });

const { error } = await spacepost.tenants.unpause("cust_123");
if (error?.statusCode === 403) console.warn("Paused by the reputation guard; contact support to review it.");

// Domains first, then the tenant (422 while it still has domains).
const { data: domains } = await spacepost.domains.list({ limit: 100 });
for (const d of domains?.data ?? []) if (d.tenant_id) console.log(d.name, "belongs to", d.tenant_id);
await spacepost.tenants.remove("cust_123");

audiences and contacts

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);

const { data: audience, error } = await spacepost.audiences.create({ name: "Newsletter" });
if (error) throw new Error(error.message);

// Create
await spacepost.contacts.create({
  audienceId: audience.id,
  email: "ada@example.com",
  firstName: "Ada",
  lastName: "Lovelace",
});

// Read by email (or by id)
const { data: contact } = await spacepost.contacts.get({ audienceId: audience.id, email: "ada@example.com" });
console.log(contact?.unsubscribed);

// Update
await spacepost.contacts.update({ audienceId: audience.id, email: "ada@example.com", firstName: "Augusta" });

// List, newest first
const { data: page } = await spacepost.contacts.list({ audienceId: audience.id, limit: 50 });
console.log(page?.data.length, page?.has_more);

// Unsubscribe manually, then delete
await spacepost.contacts.update({ audienceId: audience.id, email: "ada@example.com", unsubscribed: true });
await spacepost.contacts.remove({ audienceId: audience.id, email: "ada@example.com" });

Contacts are addressed with audienceId plus either id or email.

broadcasts

create, get, list, update(id, payload) (or update({ id, ... })), remove, send(id, { scheduledAt? }). See Broadcasts.

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost(process.env.SPACEPOST_API_KEY);
const audienceId = "0192e1c4-0000-7000-8000-0000000000a1";

// 1. Create a draft
const { data: draft, error } = await spacepost.broadcasts.create({
  audienceId,
  name: "October newsletter",
  from: "Acme <news@acme.com>",
  replyTo: "support@acme.com",
  subject: "What's new at Acme, {{{FIRST_NAME|friend}}}",
  previewText: "Three things we shipped this month",
  html: `
    <h1>Hi {{{FIRST_NAME|there}}},</h1>
    <p>Here is what is new.</p>
    <p><a href="{{{SPACEPOST_UNSUBSCRIBE_URL}}}">Unsubscribe</a></p>
  `,
});
if (error) throw new Error(error.message);

// 2. Send it now, or schedule it
const { error: sendError } = await spacepost.broadcasts.send(draft.id, { scheduledAt: "in 1 hour" });
if (sendError) throw new Error(sendError.message);

// 3. Check progress
const { data: broadcast } = await spacepost.broadcasts.get(draft.id);
console.log(broadcast?.status); // "queued" | "sending" | "sent" | "failed"

suppressions

import { SpacePost } from "@spacepost/node";

const spacepost = new SpacePost();

await spacepost.suppressions.create({ email: "do-not-mail@example.com" });

const { data } = await spacepost.suppressions.list({ limit: 100 });
for (const s of data?.data ?? []) console.log(s.email, s.reason);

await spacepost.suppressions.remove("do-not-mail@example.com"); // by email or id

Idempotency

The second argument of emails.send and batch.send takes { idempotencyKey }. See Idempotency keys.

Using the Resend SDK instead

You do not need @spacepost/node: the official resend package works unchanged against SpacePost. Set RESEND_BASE_URL=https://api.spacepost.dev or pass new Resend(key, { baseUrl: "https://api.spacepost.dev" }). See Migrating from Resend.

SpacePost extras such as tenant_id are not part of the Resend SDK’s methods, which drop unknown fields. Use @spacepost/node, resend.post("/emails", { ..., tenant_id }) or tenant-owned domains; see Platform mode.

TypeScript

All request and response types are exported: import type { SendEmailOptions, Email, Domain, Tenant, WebhookPayload } from "@spacepost/node". Emails and domains include tenant_id: string | null.