diff --git a/backend/demo.py b/backend/demo.py
new file mode 100644
index 0000000..c5e31e3
--- /dev/null
+++ b/backend/demo.py
@@ -0,0 +1,136 @@
+from dataclasses import dataclass
+from typing import Annotated, ClassVar, Iterator
+from annotated_types import (
+    SLOTS,
+    BaseMetadata,
+    GroupedMetadata,
+    Ge,
+    Le,
+    MultipleOf,
+    Predicate,
+    doc,
+)
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
+from pydantic import BaseModel, ConfigDict, Field
+from pydantic_forms.core import FormPage, post_form
+from pydantic_forms.types import State
+from pydantic_forms.exception_handlers.fastapi import form_error_handler
+from pydantic_forms.exceptions import FormException
+from pydantic_forms.core import FormPage as PydanticFormsFormPage
+from pydantic_forms.types import JSON
+
+from pydantic_forms.validators import (
+    unique_conlist,
+)
+
+
+class FormPage(PydanticFormsFormPage):
+    meta__: ClassVar[JSON] = {"hasNext": True}
+
+
+class SubmitFormPage(FormPage):
+    meta__: ClassVar[JSON] = {"hasNext": False}
+
+
+app = FastAPI()
+# Configure CORS
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],  # Allows all origins
+    allow_credentials=True,
+    allow_methods=["*"],  # Allows all methods
+    allow_headers=["*"],  # Allows all headers
+)
+app.add_exception_handler(FormException, form_error_handler)  # type: ignore[arg-type]
+
+
+@app.get("/")
+def read_root():
+    return {"Hello": "World"}
+
+
+@dataclass(frozen=True, **SLOTS)
+class ExtraData(GroupedMetadata):
+    props: dict
+
+    def __iter__(self) -> Iterator[BaseMetadata]:
+        yield Field(json_schema_extra=self.props)
+
+
+def example_backend_validation(val: int) -> bool:
+    if val == "Karel":
+        raise ValueError("No not Karel!")
+    return True
+
+
+NumberExample = Annotated[
+    int,
+    Ge(18),
+    Le(99),
+    MultipleOf(multiple_of=3),
+    Predicate(example_backend_validation),
+]
+
+StringExample = Annotated[
+    str,
+    Field(min_length=2, max_length=10),
+    Predicate(example_backend_validation),
+]
+
+
+@app.post("/form")
+async def form(form_data: list[dict] = []):
+    def form_generator(state: State):
+
+        class NameForm(FormPage):
+            model_config = ConfigDict(title="Demo form step 1")
+            name: str
+
+        name_form_data = yield NameForm
+
+        class NameValidationForm(FormPage):
+            model_config = ConfigDict(title="Demo form step 1")
+            name_with_validation: StringExample
+
+        name_validation_form_data = yield NameValidationForm
+
+        class NameAgeForm(FormPage):
+            model_config = ConfigDict(title="Demo form step 1")
+            name: StringExample
+            age: NumberExample
+
+        name_age_form_data = yield NameAgeForm
+
+        class PersonObjectForm(FormPage):
+            class Person(BaseModel):
+                name: StringExample
+                age: NumberExample
+
+            model_config = ConfigDict(title="Demo form step 1")
+            person: Person
+
+        person_object_form_data = yield PersonObjectForm
+
+        class PersonArrayForm(FormPage):
+            class Person(BaseModel):
+                name: StringExample
+                age: NumberExample
+
+            model_config = ConfigDict(title="Demo form step 1")
+            PersonList: unique_conlist(Person, min_items=1, max_items=3)
+
+        person_array_form_data = yield PersonArrayForm
+
+        return (
+            name_form_data.model_dump()
+            | name_validation_form_data.model_dump()
+            | name_age_form_data.model_dump()
+            | person_object_form_data.model_dump()
+            | person_array_form_data.model_dump()
+        )
+
+    post_form(form_generator, state={}, user_inputs=form_data)
+    return "OK!"