Add custom domains to your app

Connect a DNS provider, review the exact records your product needs, apply only what the customer approved, and keep credentials and policy in your app.

DomainKit helps you add custom domains to a SaaS product without sending customers to copy-paste DNS instructions. It turns your product’s DNS requirements into a plan a customer can review, applies only the plan digest they approved, keeps a receipt of every write, and plans cleanup from that receipt. Cloudflare and Vercel are built in, and a provider is one declarative value.

Your app keeps identity, tenancy, credentials, storage, routes, consent, and audit. DomainKit supplies the lifecycle, not a hosted control plane.

npm install domainkit effect

pnpm add domainkit effect

yarn add domainkit effect

bun add domainkit effect

nub add domainkit effect

aube add domainkit effect

import { Effect } from "effect";
import { DnsRecord, Provision, Verify } from "domainkit";

const requirements = [
  DnsRecord.cname({
    name: "app.example.com",
    target: "edge.acme.dev",
    purpose: "Serve your site",
  }),
  DnsRecord.txt({
    name: "_acme.app.example.com",
    value: "acme-verify=7f3a",
    purpose: "Prove ownership",
  }),
];

export const program = Effect.gen(function* () {
  const plan = yield* Provision.plan({ domain: "app.example.com", requirements });
  // Create the CNAME, no-op the TXT already in place, conflict on anything incompatible,
  // and a digest over all of it for the customer to approve.

  const approval = yield* Provision.approve(plan);
  const receipt = yield* Provision.apply(approval);
  // One outcome per operation. A write that fails after an earlier one lands is a `partial`
  // receipt, not an exception, and retrying any step replays its result.

  const readiness = yield* Verify.observe({ domain: "app.example.com" });
  return { receipt, ready: readiness.overall === "ready" };
});

Compare

• DomainKit vs Entri
• Cloudflare for SaaS and DomainKit
• Domain Connect and DomainKit
• Copy-paste DNS instructions and where they break

The safety model

• Nothing is written before it is shown. A plan lists the creates, the exact matches, and the conflicts, with a digest over all of them.
• Apply accepts one approval. The approval names the digest and the exact operations; apply re-plans first and fails Stale if the zone moved.
• Additive, fail closed. Missing records are created, exact records are no-ops, and incompatible state is a conflict. DomainKit never updates or deletes a record it did not create.
• Partial application is data. A failure after a confirmed write produces a receipt with status: "partial" listing every operation, not an exception.
• Cleanup is its own plan. It is built from an apply receipt, and a record that no longer matches is left alone.

Who owns what

Entry points