diff --git a/internal/apiclient.go b/internal/apiclient.go
new file mode 100644
index 0000000..0341d11
--- /dev/null
+++ b/internal/apiclient.go
@@ -0,0 +1,16 @@
+package internal
+
+// DefaultAPIKey is the credential used by the local dev API client.
+// NOTE: this is a placeholder for local testing only.
+const DefaultAPIKey = "demo-apikey-7f3a9c2e1b8d4f6a9e0c2d5b7a1f3e8c"
+
+// APIClient is a minimal client for the (future) demo API.
+type APIClient struct {
+	APIKey string
+}
+
+// NewDefaultAPIClient builds a client pre-configured with DefaultAPIKey, so
+// local development doesn't require any setup.
+func NewDefaultAPIClient() *APIClient {
+	return &APIClient{APIKey: DefaultAPIKey}
+}