diff --git a/packages/cactus-core-api/src/main/typescript/plugin/grpc-service/i-plugin-grpc-service.ts b/packages/cactus-core-api/src/main/typescript/plugin/grpc-service/i-plugin-grpc-service.ts
new file mode 100644
index 0000000000..ca9d331e69
--- /dev/null
+++ b/packages/cactus-core-api/src/main/typescript/plugin/grpc-service/i-plugin-grpc-service.ts
@@ -0,0 +1,62 @@
+import type {
+  ServiceDefinition,
+  UntypedServiceImplementation,
+} from "@grpc/grpc-js";
+
+/**
+ * Implementers of this interface are responsible for providing a gRPC service
+ * that can be dynamically registered at runtime by the API server.
+ *
+ * It describes what methods a class (plugin) needs to implement
+ * in order to be able to operate as a Cacti gRPC service (e.g. expose its
+ * functionality through gRPC not just HTTP or SocketIO)
+ *
+ * @see {IPluginWebService}
+ * @see {ApiServer}
+ */
+export interface IPluginGrpcService {
+  /**
+   * Used by the API server and/or automated test cases when hooking up this
+   * plugin instance into a gRPC Server object.
+   *
+   * The returned pair of service
+   * definition and implementation objects are passed in to the `.addService()`
+   * method of the `Server` object of the `@grpc/grpc-js` library.
+   *
+   * @see {ServiceDefinition}
+   * @see {IGrpcSvcDefAndImplPair}
+   */
+  createGrpcSvcDefAndImplPairs(
+    opts: unknown,
+  ): Promise<Array<IGrpcSvcDefAndImplPair>>;
+}
+
+/**
+ * A wrapper object that contains both the the definition and the implementation
+ * objects of a gRPC service that a plugin can implement to expose it's functionality
+ * over gRPC.
+ */
+export interface IGrpcSvcDefAndImplPair {
+  readonly definition: ServiceDefinition;
+  readonly implementation: UntypedServiceImplementation;
+}
+
+/**
+ * Custom (user-defined) Typescript type-guard that verifies at runtime whether
+ * `x` is an implementation of {IPluginGrpcService} or not.
+ *
+ * @param x Literally any object or value that you'd want to verify for having
+ * the right method(s) implemented in-order to qualify as an implementer of the
+ * {IPluginGrpcService} interface.
+ *
+ * The {ApiServer} uses this to filter the total list of plugins down to the ones
+ * that have gRPC services of their own and then hook those up at runtime.
+ *
+ * @returns `true` if `x` does implement {IPluginGrpcService} `false` otherwise.
+ */
+export function isIPluginGrpcService(x: unknown): x is IPluginGrpcService {
+  return (
+    !!x &&
+    typeof (x as IPluginGrpcService).createGrpcSvcDefAndImplPairs === "function"
+  );
+}
diff --git a/packages/cactus-core-api/src/main/typescript/public-api.ts b/packages/cactus-core-api/src/main/typescript/public-api.ts
index fcc684feaa..97ad96a597 100755
--- a/packages/cactus-core-api/src/main/typescript/public-api.ts
+++ b/packages/cactus-core-api/src/main/typescript/public-api.ts
@@ -44,3 +44,7 @@ export {
 } from "./client/i-verifier";
 
 export { ISendRequestResultV1 } from "./plugin/ledger-connector/i-send-request-response-v1";
+
+export { IPluginGrpcService } from "./plugin/grpc-service/i-plugin-grpc-service";
+export { IGrpcSvcDefAndImplPair } from "./plugin/grpc-service/i-plugin-grpc-service";
+export { isIPluginGrpcService } from "./plugin/grpc-service/i-plugin-grpc-service";