diff --git a/server/migrations/versions/2025-09-15-2112_unescape_checkout_id_placeholder_in_.py b/server/migrations/versions/2025-09-15-2112_unescape_checkout_id_placeholder_in_.py
new file mode 100644
index 0000000000..c38f25c299
--- /dev/null
+++ b/server/migrations/versions/2025-09-15-2112_unescape_checkout_id_placeholder_in_.py
@@ -0,0 +1,55 @@
+"""Unescape checkout_id placeholder in success URLs
+
+Revision ID: b797366de1fb
+Revises: bf0f120ca9a9
+Create Date: 2025-09-15 21:12:39.367225
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# Polar Custom Imports
+
+# revision identifiers, used by Alembic.
+revision = "b797366de1fb"
+down_revision = "bf0f120ca9a9"
+branch_labels: tuple[str] | None = None
+depends_on: tuple[str] | None = None
+
+ENCODED_PLACEHOLDER = "%7BCHECKOUT_ID%7D"
+DECODED_PLACEHOLDER = "{CHECKOUT_ID}"
+
+
+def upgrade() -> None:
+    op.execute(
+        f"""
+        UPDATE checkout_links
+        SET success_url = REPLACE(success_url, '{ENCODED_PLACEHOLDER}', '{DECODED_PLACEHOLDER}')
+        WHERE success_url LIKE '%{ENCODED_PLACEHOLDER}%'
+        """
+    )
+    op.execute(
+        f"""
+        UPDATE checkouts
+        SET success_url = REPLACE(success_url, '{ENCODED_PLACEHOLDER}', '{DECODED_PLACEHOLDER}')
+        WHERE success_url LIKE '%{ENCODED_PLACEHOLDER}%'
+        """
+    )
+
+
+def downgrade() -> None:
+    op.execute(
+        f"""
+        UPDATE checkout_links
+        SET success_url = REPLACE(success_url, '{DECODED_PLACEHOLDER}', '{ENCODED_PLACEHOLDER}')
+        WHERE success_url LIKE '%{DECODED_PLACEHOLDER}%'
+        """
+    )
+    op.execute(
+        f"""
+        UPDATE checkouts
+        SET success_url = REPLACE(success_url, '{DECODED_PLACEHOLDER}', '{ENCODED_PLACEHOLDER}')
+        WHERE success_url LIKE '%{DECODED_PLACEHOLDER}%'
+        """
+    )
diff --git a/server/polar/checkout/schemas.py b/server/polar/checkout/schemas.py
index d3ebf6ec11..53ff72aaee 100644
--- a/server/polar/checkout/schemas.py
+++ b/server/polar/checkout/schemas.py
@@ -7,10 +7,10 @@
     AliasChoices,
     Discriminator,
     Field,
-    HttpUrl,
     IPvAnyAddress,
     Tag,
     computed_field,
+    field_validator,
 )
 from pydantic.json_schema import SkipJsonSchema
 
@@ -46,6 +46,7 @@
     TrialConfigurationOutputMixin,
     TrialInterval,
 )
+from polar.kit.validators import validate_http_url
 from polar.models.checkout import (
     CheckoutBillingAddressFields,
     CheckoutCustomerBillingAddressFields,
@@ -97,7 +98,7 @@
     Address, Field(description="Billing address of the customer.")
 ]
 SuccessURL = Annotated[
-    HttpUrl | None,
+    str | None,
     Field(
         description=(
             "URL where the customer will be redirected after a successful payment."
@@ -204,6 +205,11 @@ class CheckoutCreateBase(
     success_url: SuccessURL = None
     embed_origin: EmbedOrigin = None
 
+    @field_validator("success_url")
+    @classmethod
+    def validate_is_http_url(cls, url: str | None) -> str | None:
+        return validate_http_url(url)
+
 
 class CheckoutPriceCreate(CheckoutCreateBase):
     """
@@ -325,6 +331,11 @@ class CheckoutUpdate(
     success_url: SuccessURL = None
     embed_origin: EmbedOrigin = None
 
+    @field_validator("success_url")
+    @classmethod
+    def validate_is_http_url(cls, url: str | None) -> str | None:
+        return validate_http_url(url)
+
 
 class CheckoutUpdatePublic(CheckoutUpdateBase):
     """Update an existing checkout session using the client secret."""
diff --git a/server/polar/checkout_link/schemas.py b/server/polar/checkout_link/schemas.py
index 266a19a615..8124df0fb8 100644
--- a/server/polar/checkout_link/schemas.py
+++ b/server/polar/checkout_link/schemas.py
@@ -1,6 +1,12 @@
 from typing import Annotated, Literal
 
-from pydantic import UUID4, AliasPath, Field, HttpUrl, computed_field
+from pydantic import (
+    UUID4,
+    AliasPath,
+    Field,
+    computed_field,
+    field_validator,
+)
 from pydantic.json_schema import SkipJsonSchema
 
 from polar.config import settings
@@ -18,6 +24,7 @@
     TimestampedSchema,
 )
 from polar.kit.trial import TrialConfigurationInputMixin, TrialConfigurationOutputMixin
+from polar.kit.validators import validate_http_url
 from polar.organization.schemas import OrganizationID
 from polar.product.schemas import (
     BenefitPublicList,
@@ -28,7 +35,7 @@
 )
 
 SuccessURL = Annotated[
-    HttpUrl | None,
+    str | None,
     Field(
         description=(
             "URL where the customer will be redirected after a successful payment."
@@ -74,6 +81,11 @@ class CheckoutLinkCreateBase(TrialConfigurationInputMixin, MetadataInputMixin, S
     )
     success_url: SuccessURL = None
 
+    @field_validator("success_url")
+    @classmethod
+    def validate_is_http_url(cls, url: str | None) -> str | None:
+        return validate_http_url(url)
+
 
 class CheckoutLinkCreateProductPrice(CheckoutLinkCreateBase):
     """
@@ -132,6 +144,11 @@ class CheckoutLinkUpdate(MetadataInputMixin, TrialConfigurationInputMixin):
     )
     success_url: SuccessURL = None
 
+    @field_validator("success_url")
+    @classmethod
+    def validate_is_http_url(cls, url: str | None) -> str | None:
+        return validate_http_url(url)
+
 
 class CheckoutLinkBase(
     MetadataOutputMixin, TrialConfigurationOutputMixin, TimestampedSchema, IDSchema
diff --git a/server/polar/kit/validators.py b/server/polar/kit/validators.py
new file mode 100644
index 0000000000..6409e6c403
--- /dev/null
+++ b/server/polar/kit/validators.py
@@ -0,0 +1,8 @@
+from pydantic import HttpUrl, TypeAdapter
+
+
+def validate_http_url(url: str | None) -> str | None:
+    if not url:
+        return None
+    TypeAdapter(HttpUrl).validate_python(url)
+    return url
diff --git a/server/tests/checkout/test_service.py b/server/tests/checkout/test_service.py
index 29be329df6..4bc033a036 100644
--- a/server/tests/checkout/test_service.py
+++ b/server/tests/checkout/test_service.py
@@ -7,7 +7,7 @@
 import pytest
 import pytest_asyncio
 import stripe as stripe_lib
-from pydantic import HttpUrl, ValidationError
+from pydantic import ValidationError
 from pytest_mock import MockerFixture
 from sqlalchemy.orm import joinedload
 
@@ -739,9 +739,7 @@ async def test_valid_success_url_with_interpolation(
             session,
             CheckoutPriceCreate(
                 product_price_id=price.id,
-                success_url=HttpUrl(
-                    "https://example.com/success?checkout_id={CHECKOUT_ID}"
-                ),
+                success_url="https://example.com/success?checkout_id={CHECKOUT_ID}",
             ),
             auth_subject,
         )
@@ -765,9 +763,7 @@ async def test_valid_success_url_with_invalid_interpolation_variable(
             session,
             CheckoutPriceCreate(
                 product_price_id=price.id,
-                success_url=HttpUrl(
-                    "https://example.com/success?checkout_id={CHECKOUT_SESSION_ID}"
-                ),
+                success_url="https://example.com/success?checkout_id={CHECKOUT_SESSION_ID}",
             ),
             auth_subject,
         )
diff --git a/server/tests/checkout_link/test_service.py b/server/tests/checkout_link/test_service.py
index d278122c99..fb67d6764d 100644
--- a/server/tests/checkout_link/test_service.py
+++ b/server/tests/checkout_link/test_service.py
@@ -2,7 +2,6 @@
 
 import pytest
 import pytest_asyncio
-from pydantic import HttpUrl
 
 from polar.auth.models import AuthSubject
 from polar.checkout_link.schemas import (
@@ -159,9 +158,7 @@ async def test_valid(
             CheckoutLinkCreateProducts(
                 payment_processor=PaymentProcessor.stripe,
                 products=[product_one_time.id],
-                success_url=HttpUrl(
-                    "https://example.com/success?checkout_id={CHECKOUT_ID}"
-                ),
+                success_url="https://example.com/success?checkout_id={CHECKOUT_ID}",
                 metadata={"key": "value"},
             ),
             auth_subject,
@@ -192,9 +189,7 @@ async def test_valid_discount(
                 payment_processor=PaymentProcessor.stripe,
                 products=[product_one_time.id],
                 discount_id=discount_fixed_once.id,
-                success_url=HttpUrl(
-                    "https://example.com/success?checkout_id={CHECKOUT_ID}"
-                ),
+                success_url="https://example.com/success?checkout_id={CHECKOUT_ID}",
                 metadata={"key": "value"},
             ),
             auth_subject,