Register a custom domain on a branch

API Reference / Functions / Register a custom domain on a branch

Registers a customer-owned domain (for example dashboard.acme.com) on the branch and points it at a target entity, chosen by entity_type + entity_id. In v1 only entity_type: function is supported (an unsupported type is rejected with 400), where entity_id is the function slug and the function must already exist on the branch (else 404).

The response includes the cname_target the customer must point their domain at with a CNAME record; the domain goes live only once that DNS resolves and a certificate is issued on the first request. A domain already registered to another resource is rejected with 409 and no detail about the owner. Re-registering the same domain for the same entity is idempotent.

Note: This endpoint is currently in Beta.

• project_id (string, path, required) The Neon project ID
• branch_id (string, path, required) The Neon branch ID

• domain (string, required) The custom domain to register (for example dashboard.acme.com). Case-insensitive; normalized to lowercase (a trailing root dot is stripped, so the 254-char bound admits a fully-qualified name whose normalized form is 253 chars). Neon-managed and internal hostnames are rejected.

• entity_type (string, required) The kind of branch entity to point the domain at. v1 supports only function; any other value is rejected with invalid_entity_type.

• entity_id (string, required) The target entity's identifier within the branch. For function this is the function slug (which must already exist on the branch).

• domain (string, optional) The registered custom domain (normalized, lowercase).

• entity_type (string, optional) The kind of branch entity the domain targets. Possible values: function (v1 supports only function). Not an enum: new values may ship in later spec versions — treat any undocumented value as unknown.

• entity_id (string, optional) The target entity's identifier within the branch. For function this is the function slug.

• cname_target (string, optional) The hostname the customer must point their custom domain at with a CNAME record. Empty when the serving region has no custom-domains front door configured. This is the activation input: point DNS here and the domain goes live (see status) once a certificate is issued on the first request.

• status (string, optional) The domain's current validity, computed by a background check: pending (still converging — point your CNAME at cname_target and wait), active (live: DNS resolves to the edge, the CA is authorized, and routing is published), or error (a fixable problem — see status_reason). Not an enum: treat any undocumented value as unknown. May be absent briefly right after registration.

• dns_status (string, optional) The DNS + CAA portion of the check: pending (no records yet), ok (resolves to our edge and the CA is authorized), misconfigured (your CNAME does not resolve to our edge), or caa_blocked (your CAA records forbid Let's Encrypt). Not an enum.

• binding_status (string, optional) Whether Neon's internal routing for the domain is published: pending, present, or missing. missing is an internal fault surfaced for support. Not an enum.

• status_reason (string, optional) A short, stable machine-readable reason for a non-active status (e.g. cname-not-pointing-at-edge, caa-blocks-lets-encrypt, binding-missing), suitable for keying an actionable hint. Empty when active or pending.

curl "https://console.neon.tech/api/v2/projects/$PROJECT_ID/branches/$BRANCH_ID/custom-domains" \
  -X POST \
  -H "Authorization: Bearer $NEON_API_KEY"

import { createNeonClient, raw } from '@neon/sdk';

const neon = createNeonClient({ apiKey: process.env.NEON_API_KEY });
const { data } = await raw.registerProjectBranchCustomDomain({
  client: neon.client,
  path: {
    project_id: process.env.PROJECT_ID,
    branch_id: process.env.BRANCH_ID
  }
});

default General Error.

The request may or may not be safe to retry, depending on the HTTP method, response status code, and whether a response was received.

• If no response is returned from the API, a network error or timeout likely occurred.
• In some cases, the request may have reached the server and been successfully processed, but the response failed to reach the client. As a result, retrying non-idempotent requests can lead to unintended results.

The following HTTP methods are considered non-idempotent: POST, PATCH, DELETE, and PUT. Retrying these methods is generally not safe. The following methods are considered idempotent: GET, HEAD, and OPTIONS. Retrying these methods is safe in the event of a network error or timeout.

Any request that returns a 503 Service Unavailable response is always safe to retry.

Any request that returns a 423 Locked response is safe to retry. 423 Locked indicates that the resource is temporarily locked, for example, due to another operation in progress.

• request_id (string, optional) Unique identifier for the request, useful for debugging. You can set this value manually by including an X-Request-ID header in the request. If not provided, the value will be generated automatically.

• code (string, required) Machine-readable code classifying the error type. See message for a human-readable explanation. Default: ``

• message (string, required) Error message