diff --git a/client/package.json b/client/package.json
index 2e99c9ec..091cdaab 100644
--- a/client/package.json
+++ b/client/package.json
@@ -1,6 +1,6 @@
 {
    "name": "gridify-client",
-   "version": "2.0.1",
+   "version": "2.0.2",
    "description": "Client JS library for the dotnet Gridify project",
    "main": "dist/index.cjs.js",
    "module": "dist/index.esm.js",
diff --git a/client/src/GridifyQueryBuilder.ts b/client/src/GridifyQueryBuilder.ts
index fc8b32de..77aa0968 100644
--- a/client/src/GridifyQueryBuilder.ts
+++ b/client/src/GridifyQueryBuilder.ts
@@ -31,7 +31,7 @@ export class GridifyQueryBuilder {
 
    addCondition(
       field: string,
-      operator: ConditionalOperator,
+      operator: ConditionalOperator | string,
       value: string | number | boolean,
       caseSensitive: boolean = true,
       escapeValue: boolean = true
@@ -45,6 +45,12 @@ export class GridifyQueryBuilder {
          filterValue = `${filterValue.toString()}/i`;
       }
 
+      if (typeof operator === "string" && !Object.values(ConditionalOperator).includes(operator as ConditionalOperator)) {
+         if (!operator.startsWith('#')) {
+            throw new Error(`Custom operators must start with the '#' character. Received: ${operator}`);
+         }
+      }
+
       var filterExpression = `${field.trim()}${operator}${filterValue}`;
       this.filteringExpressions.push({
          value: filterExpression,
diff --git a/client/test/GridifyQueryBuilder.test.ts b/client/test/GridifyQueryBuilder.test.ts
index eb6525ac..4bea348d 100644
--- a/client/test/GridifyQueryBuilder.test.ts
+++ b/client/test/GridifyQueryBuilder.test.ts
@@ -53,6 +53,24 @@ describe("GridifyQueryBuilder", () => {
    });
 });
 
+describe("GridifyQueryBuilder Custom Operator", () => {
+   it("should allow custom operator that starts with #", () => {
+      const query = new GridifyQueryBuilder()
+         .addCondition("age", "#customOp", 30)
+         .build();
+
+      expect(query.filter).toEqual("age#customOp30");
+   });
+
+   it("should throw an error for custom operator without # prefix", () => {
+      expect(() => {
+         new GridifyQueryBuilder()
+            .addCondition("age", "customOp", 30)
+            .build();
+      }).toThrow("Custom operators must start with the '#' character. Received: customOp");
+   });
+});
+
 describe("GridifyQueryBuilder Validation", () => {
    it("should allow balanced parentheses", () => {
       const query = new GridifyQueryBuilder()
@@ -161,3 +179,4 @@ describe("GridifyQueryBuilder Validation", () => {
    });
 
 });
+