diff --git a/src/common/chains.ts b/src/common/chains.ts
index 80e21698..69b7fd9f 100644
--- a/src/common/chains.ts
+++ b/src/common/chains.ts
@@ -6,4 +6,5 @@ export enum SupportedChainId {
   MAINNET = 1,
   GOERLI = 5,
   GNOSIS_CHAIN = 100,
+  SEPOLIA = 11155111,
 }
diff --git a/src/common/consts.ts b/src/common/consts.ts
index da014b94..26ab0450 100644
--- a/src/common/consts.ts
+++ b/src/common/consts.ts
@@ -1,12 +1,13 @@
 import { SupportedChainId } from './chains'
-import contractNetworks from '@cowprotocol/contracts/networks.json'
-
-const { GPv2Settlement } = JSON.parse(contractNetworks as unknown as string) as typeof contractNetworks
 
 export const BUY_ETH_ADDRESS = '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE'
 export const EXTENSIBLE_FALLBACK_HANDLER = '0x2f55e8b20D0B9FEFA187AA7d00B6Cbe563605bF5'
 export const COMPOSABLE_COW = '0xfdaFc9d1902f4e0b84f65F49f244b32b31013b74'
 
+// TODO: use addresses from the contracts repo
+const VAULT_RELAYER = '0xC92E8bdf79f0507f65a392b0ab4667716BFE0110'
+const SETTLEMENT_CONTRACT = '0x9008D19f58AAbD9eD0D60971565AA8510560ab41'
+
 /**
  * The list of supported chains.
  */
@@ -14,37 +15,35 @@ export const ALL_SUPPORTED_CHAIN_IDS: SupportedChainId[] = [
   SupportedChainId.MAINNET,
   SupportedChainId.GOERLI,
   SupportedChainId.GNOSIS_CHAIN,
+  SupportedChainId.SEPOLIA,
 ]
 
+export function mapAddressToSupportedNetworks(address: string): Record<SupportedChainId, string> {
+  return ALL_SUPPORTED_CHAIN_IDS.reduce<Record<number, string>>(
+    (acc, chainId) => ({
+      ...acc,
+      [chainId]: address,
+    }),
+    {}
+  )
+}
+
 /**
  * An object containing the addresses of the CoW Protocol settlement contracts for each supported chain.
  */
-export const COW_PROTOCOL_SETTLEMENT_CONTRACT_ADDRESS = ALL_SUPPORTED_CHAIN_IDS.reduce<Record<number, string>>(
-  (acc, chainId) => ({
-    ...acc,
-    [chainId]: GPv2Settlement[chainId].address,
-  }),
-  {}
-)
+export const COW_PROTOCOL_SETTLEMENT_CONTRACT_ADDRESS = mapAddressToSupportedNetworks(SETTLEMENT_CONTRACT)
+
+/**
+ * An object containing the addresses of the CoW Protocol Vault realyer contracts for each supported chain.
+ */
+export const COW_PROTOCOL_VAULT_RELAYER_ADDRESS = mapAddressToSupportedNetworks(VAULT_RELAYER)
 
 /**
  * An object containing the addresses of the `ExtensibleFallbackHandler` contracts for each supported chain.
  */
-export const EXTENSIBLE_FALLBACK_HANDLER_CONTRACT_ADDRESS = ALL_SUPPORTED_CHAIN_IDS.reduce<Record<number, string>>(
-  (acc, chainId) => ({
-    ...acc,
-    [chainId]: EXTENSIBLE_FALLBACK_HANDLER,
-  }),
-  {}
-)
+export const EXTENSIBLE_FALLBACK_HANDLER_CONTRACT_ADDRESS = mapAddressToSupportedNetworks(EXTENSIBLE_FALLBACK_HANDLER)
 
 /**
  * An object containing the addresses of the `ComposableCow` contracts for each supported chain.
  */
-export const COMPOSABLE_COW_CONTRACT_ADDRESS = ALL_SUPPORTED_CHAIN_IDS.reduce<Record<number, string>>(
-  (acc, chainId) => ({
-    ...acc,
-    [chainId]: COMPOSABLE_COW,
-  }),
-  {}
-)
+export const COMPOSABLE_COW_CONTRACT_ADDRESS = mapAddressToSupportedNetworks(COMPOSABLE_COW)
diff --git a/src/order-book/api.ts b/src/order-book/api.ts
index 942b001a..eb420497 100644
--- a/src/order-book/api.ts
+++ b/src/order-book/api.ts
@@ -39,6 +39,7 @@ export const ORDER_BOOK_PROD_CONFIG: ApiBaseUrls = {
   [SupportedChainId.MAINNET]: 'https://api.cow.fi/mainnet',
   [SupportedChainId.GNOSIS_CHAIN]: 'https://api.cow.fi/xdai',
   [SupportedChainId.GOERLI]: 'https://api.cow.fi/goerli',
+  [SupportedChainId.SEPOLIA]: 'https://api.cow.fi/sepolia',
 }
 
 /**
@@ -48,6 +49,7 @@ export const ORDER_BOOK_STAGING_CONFIG: ApiBaseUrls = {
   [SupportedChainId.MAINNET]: 'https://barn.api.cow.fi/mainnet',
   [SupportedChainId.GNOSIS_CHAIN]: 'https://barn.api.cow.fi/xdai',
   [SupportedChainId.GOERLI]: 'https://barn.api.cow.fi/goerli',
+  [SupportedChainId.SEPOLIA]: 'https://barn.api.cow.fi/sepolia',
 }
 
 function cleanObjectFromUndefinedValues(obj: Record<string, string>): typeof obj {
diff --git a/src/order-book/generated/models/OrderPostError.ts b/src/order-book/generated/models/OrderPostError.ts
index c1fee9ac..6aa0d310 100644
--- a/src/order-book/generated/models/OrderPostError.ts
+++ b/src/order-book/generated/models/OrderPostError.ts
@@ -23,20 +23,17 @@ export namespace OrderPostError {
         SELL_AMOUNT_OVERFLOW = 'SellAmountOverflow',
         TRANSFER_SIMULATION_FAILED = 'TransferSimulationFailed',
         ZERO_AMOUNT = 'ZeroAmount',
-        INCOMPATIBLE_SIGNING_SCHEME = 'IncompatibleSigningScheme',        
-        UNSUPPORTED_BUY_TOKEN_DESTINATION = 'UnsupportedBuyTokenDestination',
+        INCOMPATIBLE_SIGNING_SCHEME = 'IncompatibleSigningScheme',
+        TOO_MANY_LIMIT_ORDERS_UNSUPPORTED_BUY_TOKEN_DESTINATION = 'TooManyLimitOrders UnsupportedBuyTokenDestination',
         UNSUPPORTED_SELL_TOKEN_SOURCE = 'UnsupportedSellTokenSource',
         UNSUPPORTED_ORDER_TYPE = 'UnsupportedOrderType',
         INSUFFICIENT_VALID_TO = 'InsufficientValidTo',
         EXCESSIVE_VALID_TO = 'ExcessiveValidTo',
         TRANSFER_ETH_TO_CONTRACT = 'TransferEthToContract',
-        INVALID_NATIVE_SELL_TOKEN = 'InvalidNativeSellToken',
-        SAME_BUY_AND_SELL_TOKEN = 'SameBuyAndSellToken',
+        INVALID_NATIVE_SELL_TOKEN_SAME_BUY_AND_SELL_TOKEN = 'InvalidNativeSellToken SameBuyAndSellToken',
         UNSUPPORTED_SIGNATURE = 'UnsupportedSignature',
-        TOO_MANY_LIMIT_ORDERS= 'TooManyLimitOrders',
-        INVALID_APP_DATA = 'InvalidAppData',
         UNSUPPORTED_TOKEN = 'UnsupportedToken',
-        UNSUPPORTED_CUSTOM_INTERACTION = 'UnsupportedCustomInteraction',
+        UNSUPPORTED_CUSTOM_INTERACTION_INVALID_APP_DATA = 'UnsupportedCustomInteraction InvalidAppData',
         APP_DATA_HASH_MISMATCH = 'AppDataHashMismatch',
     }
 
diff --git a/src/subgraph/api.ts b/src/subgraph/api.ts
index f4a3a001..9bf11dc1 100644
--- a/src/subgraph/api.ts
+++ b/src/subgraph/api.ts
@@ -18,6 +18,7 @@ export const SUBGRAPH_PROD_CONFIG: ApiBaseUrls = {
   [SupportedChainId.MAINNET]: SUBGRAPH_BASE_URL + '/cow',
   [SupportedChainId.GNOSIS_CHAIN]: SUBGRAPH_BASE_URL + '/cow-gc',
   [SupportedChainId.GOERLI]: SUBGRAPH_BASE_URL + '/cow-goerli',
+  [SupportedChainId.SEPOLIA]: '',
 }
 
 /**
@@ -30,6 +31,7 @@ export const SUBGRAPH_STAGING_CONFIG: ApiBaseUrls = {
   [SupportedChainId.MAINNET]: SUBGRAPH_BASE_URL + '/cow-staging',
   [SupportedChainId.GNOSIS_CHAIN]: SUBGRAPH_BASE_URL + '/cow-gc-staging',
   [SupportedChainId.GOERLI]: '',
+  [SupportedChainId.SEPOLIA]: '',
 }
 
 /**