diff --git a/src/util/error.ts b/src/util/error.ts
new file mode 100644
index 00000000..c16a0268
--- /dev/null
+++ b/src/util/error.ts
@@ -0,0 +1,114 @@
+const statusCodes = {
+  ACCEPTED: 202,
+  BAD_GATEWAY: 502,
+  BAD_REQUEST: 400,
+  CONFLICT: 409,
+  CONTINUE: 100,
+  CREATED: 201,
+  EXPECTATION_FAILED: 417,
+  FAILED_DEPENDENCY: 424,
+  FORBIDDEN: 403,
+  GATEWAY_TIMEOUT: 504,
+  GONE: 410,
+  HTTP_VERSION_NOT_SUPPORTED: 505,
+  IM_A_TEAPOT: 418,
+  INSUFFICIENT_SPACE_ON_RESOURCE: 419,
+  INSUFFICIENT_STORAGE: 507,
+  INTERNAL_SERVER_ERROR: 500,
+  LENGTH_REQUIRED: 411,
+  LOCKED: 423,
+  METHOD_FAILURE: 420,
+  METHOD_NOT_ALLOWED: 405,
+  MOVED_PERMANENTLY: 301,
+  MOVED_TEMPORARILY: 302,
+  MULTI_STATUS: 207,
+  MULTIPLE_CHOICES: 300,
+  NETWORK_AUTHENTICATION_REQUIRED: 511,
+  NO_CONTENT: 204,
+  NON_AUTHORITATIVE_INFORMATION: 203,
+  NOT_ACCEPTABLE: 406,
+  NOT_FOUND: 404,
+  NOT_IMPLEMENTED: 501,
+  NOT_MODIFIED: 304,
+  OK: 200,
+  PARTIAL_CONTENT: 206,
+  PAYMENT_REQUIRED: 402,
+  PERMANENT_REDIRECT: 308,
+  PRECONDITION_FAILED: 412,
+  PRECONDITION_REQUIRED: 428,
+  PROCESSING: 102,
+  PROXY_AUTHENTICATION_REQUIRED: 407,
+  REQUEST_HEADER_FIELDS_TOO_LARGE: 431,
+  REQUEST_TIMEOUT: 408,
+  REQUEST_TOO_LONG: 413,
+  REQUEST_URI_TOO_LONG: 414,
+  REQUESTED_RANGE_NOT_SATISFIABLE: 416,
+  RESET_CONTENT: 205,
+  SEE_OTHER: 303,
+  SERVICE_UNAVAILABLE: 503,
+  SWITCHING_PROTOCOLS: 101,
+  TEMPORARY_REDIRECT: 307,
+  TOO_MANY_REQUESTS: 429,
+  UNAUTHORIZED: 401,
+  UNAVAILABLE_FOR_LEGAL_REASONS: 451,
+  UNPROCESSABLE_ENTITY: 422,
+  UNSUPPORTED_MEDIA_TYPE: 415,
+  USE_PROXY: 305,
+} as const;
+
+type StatusCode = typeof statusCodes[keyof typeof statusCodes];
+
+export class ExtendableError extends Error {
+  constructor(message: string) {
+    super(message);
+
+    /*
+     * Due to a known issue (https://github.com/microsoft/TypeScript/issues/13965)
+     * we need to set prototype manually, in order to get `instanceof` to work
+     * for classes that extend `Error`
+     */
+    Object.setPrototypeOf(this, ExtendableError.prototype);
+
+    this.name = this.constructor.name;
+
+    if (typeof Error.captureStackTrace === 'function') {
+      Error.captureStackTrace(this, this.constructor);
+    } else {
+      this.stack = new Error(message).stack;
+    }
+  }
+}
+
+type ErrorBody = {
+  status: string;
+  code: string;
+  message: string;
+};
+
+export class ForbiddenError extends ExtendableError {
+  private readonly _originalError?: Error;
+  private readonly namespace: string;
+  private readonly body: ErrorBody;
+  private readonly statusCode: StatusCode;
+
+  constructor(message: string, namespace?: string, originalError?: Error) {
+    super(message);
+
+    /*
+     * Due to a known issue (https://github.com/microsoft/TypeScript/issues/13965)
+     * we need to set prototype manually, in order to get `instanceof` to work
+     * for classes that extend `Error`
+     */
+    Object.setPrototypeOf(this, ForbiddenError.prototype);
+
+    this.namespace = namespace + ':forbidden';
+    this.name = 'ForbiddenError';
+    this.statusCode = 403;
+
+    if (originalError) {
+      this._originalError = originalError;
+    }
+
+    this.body = { status: 'error', code: this.name, message };
+  }
+}