diff --git a/README.md b/README.md
index 235d7408..055102d3 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ Since the API supports different networks and environments, there are some optio
 
 #### Environment configuration
 
-`chainId` - can be one of `SupportedChainId.MAINNET`, `SupportedChainId.GNOSIS_CHAIN`, `SupportedChainId.ARBITRUM_ONE` or `SupportedChainId.SEPOLIA`
+`chainId` - can be one of `SupportedChainId.MAINNET`, `SupportedChainId.GNOSIS_CHAIN`, `SupportedChainId.ARBITRUM_ONE`, `SupportedChainId.BASE` or `SupportedChainId.SEPOLIA`
 
 `env` - this parameter affects which environment will be used:
 
@@ -135,6 +135,7 @@ const orderBookApi = new OrderBookApi({
     [SupportedChainId.MAINNET]: 'https://YOUR_ENDPOINT/mainnet',
     [SupportedChainId.GNOSIS_CHAIN]: 'https://YOUR_ENDPOINT/gnosis_chain',
     [SupportedChainId.ARBITRUM]: 'https://YOUR_ENDPOINT/arbitrum_one',
+    [SupportedChainId.BASE]: 'https://YOUR_ENDPOINT/base',
     [SupportedChainId.SEPOLIA]: 'https://YOUR_ENDPOINT/sepolia',
   },
 })
diff --git a/package.json b/package.json
index ec7f7b3a..1f780415 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@cowprotocol/cow-sdk",
-  "version": "5.6.0",
+  "version": "5.7.0-RC.0",
   "license": "(MIT OR Apache-2.0)",
   "files": [
     "/dist"
@@ -100,4 +100,4 @@
     "typescript",
     "subgraph"
   ]
-}
+}
\ No newline at end of file
diff --git a/src/common/chains.ts b/src/common/chains.ts
index 28e847b4..8e916da4 100644
--- a/src/common/chains.ts
+++ b/src/common/chains.ts
@@ -6,5 +6,6 @@ export enum SupportedChainId {
   MAINNET = 1,
   GNOSIS_CHAIN = 100,
   ARBITRUM_ONE = 42161,
+  BASE = 8453,
   SEPOLIA = 11155111,
 }
diff --git a/src/common/configs.ts b/src/common/configs.ts
index 488f7839..ad3cd48e 100644
--- a/src/common/configs.ts
+++ b/src/common/configs.ts
@@ -1,6 +1,6 @@
-import { SupportedChainId } from './chains'
 import { BackoffOptions } from 'exponential-backoff'
 import { RateLimiterOpts } from 'limiter/dist/esm'
+import { SupportedChainId } from './chains'
 
 /**
  * IPFS configuration.
@@ -42,6 +42,8 @@ export type PartialApiContext = Partial<ApiContext>
 /**
  * @property {string} [1] The base URL for the mainnet API.
  * @property {string} [100] The base URL for the Gnosis Chain API.
+ * @property {string} [42161] The base URL for the Arbitrum One API.
+ * @property {string} [8453] The base URL for the Base API.
  * @property {string} [11155111] The base URL for the Sepolia testnet API.
  */
 export type ApiBaseUrls = Record<SupportedChainId, string>
@@ -53,6 +55,8 @@ export type ApiBaseUrls = Record<SupportedChainId, string>
  * {@link SupportedChainId Supported chains} are:
  * - Mainnet
  * - Gnosis Chain
+ * - Arbitrum One
+ * - Base
  * - Sepolia
  *
  * Each chain has it's own API, and each API has it's own base URL.
diff --git a/src/order-book/api.ts b/src/order-book/api.ts
index bf2e457e..0af88598 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.ARBITRUM_ONE]: 'https://api.cow.fi/arbitrum_one',
+  [SupportedChainId.BASE]: 'https://api.cow.fi/base',
   [SupportedChainId.SEPOLIA]: 'https://api.cow.fi/sepolia',
 }
 
@@ -49,6 +50,7 @@ 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.ARBITRUM_ONE]: 'https://barn.api.cow.fi/arbitrum_one',
+  [SupportedChainId.BASE]: 'https://barn.api.cow.fi/base',
   [SupportedChainId.SEPOLIA]: 'https://barn.api.cow.fi/sepolia',
 }
 
diff --git a/src/subgraph/api.ts b/src/subgraph/api.ts
index 4b4dcde3..13337e0b 100644
--- a/src/subgraph/api.ts
+++ b/src/subgraph/api.ts
@@ -25,6 +25,7 @@ export const SUBGRAPH_PROD_CONFIG: SubgraphApiBaseUrls = {
   [SupportedChainId.MAINNET]: SUBGRAPH_BASE_URL + '/cow',
   [SupportedChainId.GNOSIS_CHAIN]: SUBGRAPH_BASE_URL + '/cow-gc',
   [SupportedChainId.ARBITRUM_ONE]: null,
+  [SupportedChainId.BASE]: null,
   [SupportedChainId.SEPOLIA]: null,
 }
 
@@ -38,6 +39,7 @@ export const SUBGRAPH_STAGING_CONFIG: SubgraphApiBaseUrls = {
   [SupportedChainId.MAINNET]: SUBGRAPH_BASE_URL + '/cow-staging',
   [SupportedChainId.GNOSIS_CHAIN]: SUBGRAPH_BASE_URL + '/cow-gc-staging',
   [SupportedChainId.ARBITRUM_ONE]: null,
+  [SupportedChainId.BASE]: null,
   [SupportedChainId.SEPOLIA]: null,
 }