CoW Swap is the first trading interface built on top of CoW Protocol.

It allows you to buy and sell tokens using gasless orders that are settled peer-to-peer among its users or into any on-chain liquidity source while providing MEV protection.

First install Dependencies:

pnpm install

To upgrade @cowprotocol/cow-sdk and all @cowprotocol/sdk-* packages to the latest published versions:

pnpm upgrade-sdk-latest
pnpm install

Or, if you want to use @cowprotocol/sdk preview versions like "@cowprotocol/cow-sdk": "7.0.4-pr-546-c04641f0.0", then:

• run pnpm upgrade-sdk-preview https://github.com/cowprotocol/cow-sdk/pull/787 with a link to SDK PR with deployed previews
• run PACKAGE_READ_AUTH_TOKEN=XXX pnpm run install:ci instead of just pnpm install
• the token must be generated in GitHub with read:packages permissions

Start CoW Swap on http://localhost:3000

pnpm start

Environment selection for cowswap-frontend is configured explicitly via REACT_APP_ENVIRONMENT in the app-level .env.* files:

• Supported values: local, development, pr, staging, production, ens

• apps/cowswap-frontend/.env.development -> local

• apps/cowswap-frontend/.env.dev -> development

• apps/cowswap-frontend/.env.staging -> staging

• apps/cowswap-frontend/.env.production -> production

Build the project. The static files will be generated in the build folder.

pnpm run build

cowswap-frontend generates production sourcemaps for Sentry.

• Runtime error reporting still uses REACT_APP_SENTRY_DSN.
• Build-time sourcemap upload uses SENTRY_AUTH_TOKEN.
• SENTRY_ORG and SENTRY_PROJECT are optional overrides. Defaults: cowprotocol and cowswap

If SENTRY_AUTH_TOKEN is not set, the build still succeeds, but sourcemaps are not uploaded to Sentry.

pnpm run test

Start the Explorer on http://localhost:4200

Read more about the Explorer

pnpm run start:explorer

Explorer environment selection is configured explicitly via REACT_APP_ENVIRONMENT. See apps/explorer/.env.example.

pnpm run build:explorer

Start cow.fi on http://localhost:3001

pnpm run start:cowfi

cow-fi no longer infers its environment from the hostname. Set NEXT_PUBLIC_ENVIRONMENT explicitly. See apps/cow-fi/.env.example.

pnpm run build:cowfi

Start the Widget Configurator on http://localhost:4200/widget-configurator

# Start
pnpm run start:widget

# Build
pnpm run build:widget

Start the Cosmos UI Library on http://localhost:5000

pnpm run cosmos

CoW Swap's e2e suite lives in apps/cowswap-e2e-tests (Playwright + Synpress). See that app's README for the full guide — mocks, page objects, wallet fixtures, and troubleshooting.

⚠️ Add the required environment variables to your root .env.local file:

• INTEGRATION_TEST_PRIVATE_KEY=<a throwaway Sepolia private key>
• REACT_APP_NETWORK_URL_11155111=<a Sepolia RPC URL>

Most specs — including the PR smoke subset run in CI — use a fast mock wallet fixture and need no setup beyond the env vars above. A separate Synpress fixture drives a real MetaMask extension for scenarios that must exercise actual wallet UI; only specs using that fixture need a pre-built cache:

pnpm e2e:build-cache

Neither the e2e-pw-smoke nor e2e-pw-nightly CI workflow runs this step — no spec in the suite currently uses the Synpress fixture, so CI never touches .cache-synpress. If a spec starts using it, its workflow must build or restore the cache first.

Then run the suite. Playwright builds and serves the app itself, so there's no need to start a dev server in a separate terminal:

# Full suite
pnpm e2e

# PR smoke subset only
pnpm e2e:smoke

# Playwright UI mode, for interactive debugging
pnpm e2e:ui

Analyze CoW Swap bundle:

# Use one of the following templates: "sunburst" | "treemap" | "network" | "raw-data" | "list";
ANALYZE_BUNDLE=true ANALYZE_BUNDLE_TEMPLATE=sunburst pnpm run build

You should set your own RPC endpoints.

One simple way to do this, is by defining your own REACT_APP_INFURA_KEY environment var.

Alternatively you can define the RPC URLs directly with the following environment variables:

REACT_APP_NETWORK_URL_1: https://...
REACT_APP_NETWORK_URL_56: https://...
REACT_APP_NETWORK_URL_100: https://rpc.gnosis.gateway.fm
REACT_APP_NETWORK_URL_137: https://...
REACT_APP_NETWORK_URL_8453: https://...
REACT_APP_NETWORK_URL_9745: https://rpc.plasma.to
REACT_APP_NETWORK_URL_42161: https://...
REACT_APP_NETWORK_URL_43114: https://...
REACT_APP_NETWORK_URL_57073: https://rpc-ten.inkonchain.com
REACT_APP_NETWORK_URL_59144: https://rpc.linea.build
REACT_APP_NETWORK_URL_11155111: https://...

Additionally, if you plan to run the integration tests locally you must define:

INTEGRATION_TESTS_INFURA_KEY: YOUR_INFURA_KEY
INTEGRATION_TESTS_PRIVATE_KEY: YOUR_TEST_WALLET_PRIVATE_KEY

Fee quote requests and posting orders are sent to the Orderbook API. This API has the responsibility of collecting orders and handing them to the solvers.

The reference implementation of the API is CoW Protocol Services.

The API endpoint is configured using the environment variable REACT_APP_ORDER_BOOK_URLS:

REACT_APP_ORDER_BOOK_URLS='{"1":"https://YOUR_HOST","100":"https://YOUR_HOST","5":"https://YOUR_HOST"}

For apps/cowswap-frontend:

REACT_APP_SENTRY_DSN=https://<public-dsn>
SENTRY_AUTH_TOKEN=<sentry-auth-token>

Optional overrides for the build-time upload target:

SENTRY_ORG=cowprotocol
SENTRY_PROJECT=cowswap

SENTRY_AUTH_TOKEN is the only required secret for source map upload. The org and project values are public identifiers and already default to the values above.

The BFF API is a helper API that provides some additional data to the frontend. It is a API that is used to enhance the frontend experience enabling some features. It is not consider a required API for CoW Swap core functionality, the app will still allow the user to place order and will have some fallback logics in case this API is not available.

The reference implementation of the API is BFF (Backend For Frontend).

The API endpoint is configured using the environment variable REACT_APP_BFF_BASE_URL:

REACT_APP_BFF_BASE_URL=https://bff.cow.fi

The CMS API is a helper API that provides some additional content to the frontend.

It is not considered a required API for CoW Swap core functionality, the app will still allow the user to place orders and will have some fallback logic in case this API is not available.

The reference implementation of the API is CMS API.

The API endpoint is configured using the environment variable REACT_APP_CMS_BASE_URL:

REACT_APP_CMS_BASE_URL=https://cms.cow.fi/api

CoW Swap tries to find the best price available on-chain using some price feeds.

All price feeds are enabled by default, but they can be individually disabled by using an environment variable:

The app will attach some metadata to all orders.

This metadata will be sent to the smart contract as a hexadecimal value in an order field called AppData. This value comes from hashing the content of a metadata JSON containing some information about the trade (using keccak256 on the UTF-8 bytes).

The format of the JSON follows the format defined in @cowprotocol/sdk-app-data.

To set your own AppData, change REACT_APP_FULL_APP_DATA_<environment> environment variable. For more details, check out the environment file (<.env>)

pnpm run build:cowfi also generates ./sitemap.xml file.

See next-sitemap.config.js

In case of problems with the service worker cache you force a reset using emergency.js The plan:

1. const resetCacheInCaseOfEmergency = false - change false to true
2. Deploy a new version to production

emergency.js is not cached by browser and loaded before all.

Each app’s vercel.json uses cd ../.. then npx pnpm@10.30.3 so installs match root packageManager and avoid Vercel’s default pnpm 9 (which can trigger ERR_PNPM_LOCKFILE_CONFIG_MISMATCH with this lockfile).

Project settings that must line up (if deploys fail for unclear reasons):

1. Root Directory for that Vercel project should be the app folder (e.g. apps/cow-fi). If it is the monorepo root instead, cd ../.. is wrong and install reads the wrong tree.
2. Build & Development → no Install Command / Build Command override in the dashboard that replaces vercel.json (or align them with the repo).
3. Node.js version on Vercel should be current LTS (Corepack / npx expect a recent Node).
4. ERR_PNPM_LOCKFILE_CONFIG_MISMATCH: run pnpm install locally with pnpm 10.30.3, commit any pnpm-lock.yaml change, and ensure root package.json pnpm.* config was not edited without reinstalling.
5. Ignored Build Step: use node tools/scripts/ignore-build-step.js --app=… — do not use a broken one-line [ … || … ] sh test (see below).

Since this repo includes multiple apps, we do not want to build all of them on each PR because it causes long build queues in Vercel.
Some apps (see the list below) are not required to be built on each PR so we run them only a PR is labeled with a specific label. This label is defined in the project settings on Vercel in Settings/Git/Ignored Build Step script. Use the Node script below (do not use a one-line sh/bash test with [ ... || ... ] inside a single [ — POSIX [ does not support || there, which breaks branch names like feature/foo and logs [: missing \]'`).

For example, the label for the widget-configurator is preview-widget-cfg:

node tools/scripts/ignore-build-step.js --app=preview-widget-cfg

List of applications and their labels:

• widget-configurator: preview-widget-cfg
• cosmos: preview-cosmos
• sdk-tools: preview-sdk-tools

1. Oveall Architecture
2. Amounts formatting
3. ABIs