diff --git a/next/src/form.ts b/next/src/form.ts
index 671d7ce4..fb228227 100644
--- a/next/src/form.ts
+++ b/next/src/form.ts
@@ -6,6 +6,7 @@ import { getErrorMessage } from './errors/messages'
 import { buildFieldSchema } from './field/schema'
 import { calculateFinalSchema, updateFieldProperties } from './mutations'
 import { validateSchema } from './validation/schema'
+import { registerCustomFunctionsToJsonLogic } from './validation/json-logic'
 
 export { ValidationOptions } from './validation/schema'
 
@@ -255,6 +256,10 @@ export function createHeadlessForm(
     options: options.validationOptions,
   })
 
+  if (options.validationOptions?.customJsonLogicOps) {
+    registerCustomFunctionsToJsonLogic(options.validationOptions.customJsonLogicOps)
+  }
+
   const fields = buildFields({ schema: updatedSchema, originalSchema: schema, strictInputType })
 
   // TODO: check if we need this isError variable exposed
diff --git a/next/src/validation/json-logic.ts b/next/src/validation/json-logic.ts
index 3c5c5d30..96f7f2fc 100644
--- a/next/src/validation/json-logic.ts
+++ b/next/src/validation/json-logic.ts
@@ -3,6 +3,16 @@ import type { ValidationError, ValidationErrorPath } from '../errors'
 import type { JsfObjectSchema, JsfSchema, JsonLogicContext, JsonLogicRules, JsonLogicSchema, NonBooleanJsfSchema, ObjectValue, SchemaValue } from '../types'
 import jsonLogic from 'json-logic-js'
 
+/**
+ * Register user defined functions to be used in JSON Logic rules.
+ * @param customJsonLogicOps An object containing custom JSON Logic operations to register
+ */
+export function registerCustomFunctionsToJsonLogic(customJsonLogicOps: Record<string, (...args: any[]) => any>) {
+  for (const [name, func] of Object.entries(customJsonLogicOps)) {
+    jsonLogic.add_operation(name, func)
+  }
+}
+
 /**
  * Builds a json-logic context based on a schema and the current value
  * @param schema - The schema to build the context from
diff --git a/next/src/validation/schema.ts b/next/src/validation/schema.ts
index 63d7ccb0..04f6992d 100644
--- a/next/src/validation/schema.ts
+++ b/next/src/validation/schema.ts
@@ -27,6 +27,12 @@ export interface ValidationOptions {
    * @default false
    */
   allowForbiddenValues?: boolean
+
+  /**
+   * Custom jsonLogic operations to register (only applies once at setup)
+   * Format: { [operationName]: (...args: any[]) => any }
+   */
+  customJsonLogicOps?: Record<string, (...args: any[]) => any>
 }
 
 /**
diff --git a/next/test/validation/json-logic-v0.test.js b/next/test/validation/json-logic-v0.test.js
index 8fdf2bbe..2b1ddc1b 100644
--- a/next/test/validation/json-logic-v0.test.js
+++ b/next/test/validation/json-logic-v0.test.js
@@ -1,6 +1,7 @@
-import { createHeadlessForm } from '@/createHeadlessForm'
 import { afterEach, beforeEach, describe, expect, it } from '@jest/globals'
+
 import { mockConsole, restoreConsoleAndEnsureItWasNotCalled } from '../test-utils'
+
 import {
   badSchemaThatWillNotSetAForcedValue,
   createSchemaWithRulesOnFieldA,
@@ -15,6 +16,7 @@ import {
   schemaWithComputedAttributeThatDoesntExist,
   schemaWithComputedAttributeThatDoesntExistDescription,
   schemaWithComputedAttributeThatDoesntExistTitle,
+  schemaWithCustomValidationFunction,
   schemaWithDeepVarThatDoesNotExist,
   schemaWithDeepVarThatDoesNotExistOnFieldset,
   schemaWithInlinedRuleOnComputedAttributeThatReferencesUnknownVar,
@@ -30,6 +32,7 @@ import {
   schemaWithUnknownVariableInValidations,
   schemaWithValidationThatDoesNotExistOnProperty,
 } from './json-logic.fixtures'
+import { createHeadlessForm } from '@/createHeadlessForm'
 
 beforeEach(mockConsole)
 afterEach(restoreConsoleAndEnsureItWasNotCalled)
@@ -446,4 +449,23 @@ describe('jsonLogic: cross-values validations', () => {
       expect(handleValidation({ field_a: 20, field_b: 41 }).formErrors).toEqual()
     })
   })
+
+  describe('custom operators', () => {
+    it('custom function', () => {
+      const { handleValidation } = createHeadlessForm(schemaWithCustomValidationFunction, { strictInputType: false, validationOptions: { customJsonLogicOps: { is_hello: a => a === 'hello world' } } })
+      expect(handleValidation({ field_a: 'hello world' }).formErrors).toEqual(undefined)
+      const { formErrors } = handleValidation({ field_a: 'wrong text' })
+      expect(formErrors?.field_a).toEqual('Invalid hello world')
+    })
+
+    it('custom function are form specific', () => {
+      const { handleValidation } = createHeadlessForm(schemaWithCustomValidationFunction, { strictInputType: false, validationOptions: { customJsonLogicOps: { is_hello: a => a === 'hello world' } } })
+      expect(handleValidation({ field_a: 'hello world' }).formErrors).toEqual(undefined)
+      const { formErrors } = handleValidation({ field_a: 'wrong text' })
+      expect(formErrors?.field_a).toEqual('Invalid hello world')
+
+      const { handleValidation: handleValidation2 } = createHeadlessForm(schemaWithCustomValidationFunction, { strictInputType: false, validationOptions: { customJsonLogicOps: { is_hello: a => a === 'hello world!' } } })
+      expect(handleValidation2({ field_a: 'hello world!' }).formErrors).toEqual(undefined)
+    })
+  })
 })
diff --git a/next/test/validation/json-logic.fixtures.js b/next/test/validation/json-logic.fixtures.js
index 4dc7d45b..15a70616 100644
--- a/next/test/validation/json-logic.fixtures.js
+++ b/next/test/validation/json-logic.fixtures.js
@@ -744,3 +744,22 @@ export const schemaWithReduceAccumulator = {
     },
   },
 }
+
+export const schemaWithCustomValidationFunction = {
+  'properties': {
+    field_a: {
+      'type': 'string',
+      'x-jsf-logic-validations': ['hello_world'],
+    },
+  },
+  'x-jsf-logic': {
+    validations: {
+      hello_world: {
+        errorMessage: 'Invalid hello world',
+        rule: {
+          is_hello: { var: 'field_a' },
+        },
+      },
+    },
+  },
+}