Launchday Docs

What is Launchday?

Launchday is a backend platform for app developers. It handles the operational infrastructure every paid app needs, so you can focus on building, not plumbing.

Core concepts

Product

The top-level entity: your app. A product can have multiple platforms (macOS, iOS, Windows, etc.), each with its own releases and namespace.

Platform & namespace

Each platform gets a namespace, a short slug like com.example.myapp. Namespaces are unique per platform, so you can reuse the same identifier across macOS and Windows. The namespace drives the download and appcast URLs.

Configurations

Email and storage configs are org-level resources you create once and attach to any product or platform. This lets you share a single Mailgun domain or S3 bucket across all your products.

Signed payloads

License validation responses are signed with a per-product Ed25519 key. Your app verifies the signature locally with no network call needed after the first activation.

Getting started

1. Create a product

In the dashboard, create a product and give it a name. Then add at least one platform (e.g. macOS) with a namespace. The namespace is a reverse-domain identifier like com.example.myapp.

2. Configure your API endpoint

By default, all API calls go directly to api.launchday.one — no DNS setup required. Pass your namespace and platform in the request body to identify your product. This is the standard integration path and requires no domain configuration.

Optional (Studio plan): add a CNAME to serve the license API from your own subdomain. When a custom domain is set, the namespace and platform fields are no longer required — the host header identifies your product automatically.

No backend needed? If you sell through Stripe or Paddle, Launchday's Payment Webhooks feature can generate and email a license to your customer automatically when a payment completes — no server-side code required on your end.

launchday.yourapp.com  CNAME  api.launchday.one   // license API (Studio plan)

If using a custom domain, set it on your platform in Products → your product → Platforms, then add the domain in your Fly dashboard or contact support to provision the TLS certificate.

3. Get your public key

Go to Products → your product → Settings → Public Key and copy the hex-encoded Ed25519 public key. Bundle it with your app. It never changes unless you rotate keys.

4. Attach configurations

Create an email config and a storage config under Settings, then link them to your product. Without an email config, license emails won't be sent. Without a storage config, release uploads will use the default Launchday storage.

Activate a license on a device for the first time, or check an already-activated license.

POST /v1/license/validate

Request body

{
  "license_key": "MYAPP-XXXX-XXXX-XXXX",
  "device_id":  "unique-device-identifier",
  "mode":       "activate",
  "namespace":  "com.example.myapp",  // required by default; omit only with a Studio plan custom domain
  "platform":   "macos"               // required by default; omit only with a Studio plan custom domain
}

{
  "valid":          true,
  "license_status": "active",
  "key_id":         "abc123",
  "signature":     "a1b2c3...hex",
  "payload": {
    "license_key":     "MYAPP-XXXX-XXXX-XXXX",
    "device_id":       "unique-device-identifier",
    "namespace":       "com.example.myapp",
    "license_status":  "active",
    "issued_at":       "2026-02-27T12:00:00Z",
    "expires_at":      "2027-02-27T12:00:00Z"
  }
}

Error responses

// 200 OK (invalid license) or 4xx
{ "error": "license_not_found" }
{ "error": "revoked" }
{ "error": "expired" }
{ "error": "max_devices_reached" }
{ "error": "device_not_bound" }
{ "error": "invalid_mode" }

Remove a device binding. Call this when the user uninstalls or transfers their license.

POST /v1/license/deactivate

Request body

{
  "license_key": "MYAPP-XXXX-XXXX-XXXX",
  "device_id":  "unique-device-identifier"
}

{ "deactivated": true }

Creates a new license (or resends an existing one) and emails it to the user. Requires an email config linked to the product.

POST /v1/license/request

Request body

{
  "email": "user@example.com"
}

{
  "success": true,
  "message": "If an account exists, a license key has been sent."
}

Offline verification

Every successful validate response includes a payload and signature. Verify them locally using your bundled Ed25519 public key.

1. 1 JSON-encode the payload object. Field order is alphabetical (Go's json.Marshal): device_id, expires_at, issued_at, license_key, license_status, namespace
2. 2 Verify the hex-encoded signature against the encoded bytes using Ed25519
3. 3 Check expires_at is in the future and license_status is "active"

Swift example

import CryptoKit

func verifyPayload(
  _ response: ValidationResponse,
  publicKeyHex: String
) -> Bool {
  guard
    let pubKeyData = Data(hexString: publicKeyHex),
    let pubKey = try? Curve25519.Signing
      .PublicKey(rawRepresentation: pubKeyData),
    let sigData = Data(hexString: response.signature),
    let payloadData = try? JSONEncoder()
      .encode(response.payload)  // must match Go field order
  else { return false }

  guard pubKey.isValidSignature(
    sigData, for: payloadData
  ) else { return false }

  let expires = response.payload.expiresAt
  return expires > Date() &&
    response.payload.licenseStatus == "active"
}

Public endpoint. No authentication required.

POST /v1/waitlist/join

Request body

{
  "email":                "user@example.com",
  "product_id":          "uuid-of-product",
  "form_token":          "hmac-hex-string",
  "cf_turnstile_response": "turnstile-token"  // optional
}

No CNAME required — requests go directly to https://api.launchday.one/v1/waitlist/join. Set a Waitlist Domain on your platform to restrict submissions to requests originating from that domain.

{ "success": true }

Setup

1. 1 In your product dashboard, go to Settings → Payments
2. 2 Click Add webhook — choose your payment provider (Stripe or Paddle) and the scope (all platforms or a specific platform)
3. 3 Copy the generated webhook URL from Launchday
4. 4 Paste it as a webhook endpoint in your Stripe dashboard or Paddle dashboard
5. 5 Copy the signing secret generated by Stripe or Paddle and paste it back into Launchday on the same webhook settings screen

Scope behaviour

Email: Mailgun

Launchday uses Mailgun to deliver license keys and waitlist notifications. Additional providers (SendGrid, Postmark, etc.) may be supported in future.

Setup

1. 1 In your Mailgun dashboard, add and verify your sending domain (e.g. mail.yourapp.com)
2. 2 Generate a sending API key (not the account key) in Mailgun → API Keys
3. 3 In the Launchday dashboard, go to Settings → Email configs → New and fill in the fields below
4. 4 Link the config to your product under Products → your product → Settings

Fields

Storage

Launchday provides managed storage for your releases by default. You can also bring your own S3-compatible bucket — AWS S3, Backblaze B2, MinIO, and any other S3-compatible provider are supported.

Setup

1. 1 Create a bucket in your storage provider and note the bucket name, region, and endpoint (if applicable)
2. 2 Generate an access key/secret with read+write permissions on the bucket
3. 3 Go to Settings → Storage configs → New in the dashboard and fill in the fields below
4. 4 Link the config to your product under Products → your product → Settings

Fields