# Run-time environment variables

The app instance could be customized by passing following variables to NodeJS environment at run-time. See their list below.

**IMPORTANT NOTE!** For _production_ build purposes all json-like values should be single-quoted. If it contains a hash (`#`) or a dollar-sign (`$`) the whole value should be wrapped in single quotes as well (see `dotenv` [readme](https://github.com/bkeepers/dotenv#variable-substitution) for the reference)

## Table of contents
- [App configuration](ENVS.md#app-configuration)
- [Blockchain parameters](ENVS.md#blockchain-parameters)
- [API configuration](ENVS.md#api-configuration)
- [UI configuration](ENVS.md#ui-configuration)
  - [Homepage](ENVS.md#homepage)
  - [Sidebar](ENVS.md#sidebar)
  - [Footer](ENVS.md#footer)
  - [Favicon](ENVS.md#favicon)
  - [Views](ENVS.md#views)
    - [Block](ENVS.md#block-views)
  - [Misc](ENVS.md#misc)
- [App features](ENVS.md#app-features)
  - [My account](ENVS.md#my-account)
  - [Address verification](ENVS.md#address-verification-in-my-account) in "My account"
  - [Blockchain interaction](ENVS.md#blockchain-interaction-writing-to-contract-etc) (writing to contract, etc.)
  - [Banner ads](ENVS.md#banner-ads)
  - [Text ads](ENVS.md#text-ads)
  - [Beacon chain](ENVS.md#beacon-chain)
  - [Rollup (L2) chain](ENVS.md#rollup-l2-chain)
  - [Export data to CSV file](ENVS.md#export-data-to-csv-file)
  - [Google analytics](ENVS.md#google-analytics)
  - [Mixpanel analytics](ENVS.md#mixpanel-analytics)
  - [GraphQL API documentation](ENVS.md#graphql-api-documentation)
  - [REST API documentation](ENVS.md#rest-api-documentation)
  - [Marketplace](ENVS.md#marketplace)
  - [Solidity to UML diagrams](ENVS.md#solidity-to-uml-diagrams)
  - [Blockchain statistics](ENVS.md#blockchain-statistics)
  - [Web3 wallet integration](ENVS.md#web3-wallet-integration-add-token-or-network-to-the-wallet) (add token or network to the wallet)
  - [Verified tokens info](ENVS.md#verified-tokens-info)
  - [Sentry error monitoring](ENVS.md#sentry-error-monitoring)
- [3rd party services configuration](ENVS.md#external-services-configuration)

&nbsp;

## App configuration

| Variable | Type| Description | Compulsoriness | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_APP_PROTOCOL | `http \| https` | App url schema | - | `https` | `http` |
| NEXT_PUBLIC_APP_HOST | `string` | App host | Required | - | `blockscout.com` |
| NEXT_PUBLIC_APP_PORT | `number` | Port where app is running | - | `3000` | `3001` |
| NEXT_PUBLIC_USE_NEXT_JS_PROXY | `boolean` | Tells the app to proxy all APIs request through the NextJS app. **We strongly advise not to use it in the production environment**, since it can lead to performance issues of the NodeJS server | - | `false` | `true` |

&nbsp;

## Blockchain parameters

| Variable | Type| Description | Compulsoriness | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_NETWORK_NAME | `string` | Displayed name of the network | Required | - | `Gnosis Chain` |
| NEXT_PUBLIC_NETWORK_SHORT_NAME | `string` | Used for SEO attributes (e.g, page description) | - | -  | `OoG` |
| NEXT_PUBLIC_NETWORK_ID | `number` | Chain id, see [https://chainlist.org](https://chainlist.org) for the reference | Required | -  | `99` |
| NEXT_PUBLIC_NETWORK_RPC_URL | `string` | Chain public RPC server url, see [https://chainlist.org](https://chainlist.org) for the reference | - | - | `https://core.poa.network` |
| NEXT_PUBLIC_NETWORK_CURRENCY_NAME | `string` | Network currency name | - | - | `Ether` |
| NEXT_PUBLIC_NETWORK_CURRENCY_SYMBOL | `string` | Network currency symbol | - | - | `ETH` |
| NEXT_PUBLIC_NETWORK_CURRENCY_DECIMALS | `string` | Network currency decimals | - | `18` | `6` |
| NEXT_PUBLIC_NETWORK_VERIFICATION_TYPE | `validation` or `mining` | Verification type in the network | - | `mining` | `validation` |
| NEXT_PUBLIC_IS_TESTNET | `boolean`| Set to true if network is testnet | - | `false` | `true` |

&nbsp;

## API configuration

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_API_PROTOCOL | `http \| https` | Main API protocol | - | `https` | `http` |
| NEXT_PUBLIC_API_HOST | `string` | Main API host | Required | - | `blockscout.com` |
| NEXT_PUBLIC_API_PORT | `number` | Port where API is running on the host | - | - | `3001` |
| NEXT_PUBLIC_API_BASE_PATH | `string` | Base path for Main API endpoint url | - | - | `/poa/core` |
| NEXT_PUBLIC_API_WEBSOCKET_PROTOCOL | `ws \| wss` | Main API websocket protocol | - | `wss` | `ws` |

&nbsp;

## UI configuration

### Homepage

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_HOMEPAGE_CHARTS | `Array<'daily_txs' \| 'coin_price' \| 'market_cap'>` | List of charts displayed on the home page | - | - | `['daily_txs','coin_price','market_cap']` |
| NEXT_PUBLIC_HOMEPAGE_PLATE_TEXT_COLOR | `string` | Text color of the hero plate on the homepage (escape "#" symbol if you use HEX color codes or use rgba-value instead) | - | `white` | `\#DCFE76` |
| NEXT_PUBLIC_HOMEPAGE_PLATE_BACKGROUND | `string` | Background css value for hero plate on the homepage (escape "#" symbol if you use HEX color codes or use rgba-value instead) | - | `radial-gradient(103.03% 103.03% at 0% 0%, rgba(183, 148, 244, 0.8) 0%, rgba(0, 163, 196, 0.8) 100%), var(--chakra-colors-blue-400)` | `radial-gradient(at 15% 86%, hsla(350,65%,70%,1) 0px, transparent 50%)` \| `no-repeat bottom 20% right 0px/100% url(https://placekitten/1400/200)` |
| NEXT_PUBLIC_HOMEPAGE_SHOW_GAS_TRACKER | `boolean` | Set to false if network doesn't have gas tracker | - | `true` | `false` |
| NEXT_PUBLIC_HOMEPAGE_SHOW_AVG_BLOCK_TIME | `boolean` | Set to false if average block time is useless for the network | - | `true` | `false` |

&nbsp;

### Sidebar

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_NETWORK_LOGO | `string` | Network logo; if not provided, placeholder will be shown; *Note* the logo height should be 20px and width less than 120px | - | - | `https://placekitten.com/240/40` |
| NEXT_PUBLIC_NETWORK_LOGO_DARK | `string` | Network logo for dark color mode; if not provided, **inverted** regular logo will be used instead | - | - | `https://placekitten.com/240/40` |
| NEXT_PUBLIC_NETWORK_ICON | `string` | Network icon; used as a replacement for regular network logo when nav bar is collapsed; if not provided, placeholder will be shown; *Note* the icon size should be at least 60px by 60px | - | - | `https://placekitten.com/60/60` |
| NEXT_PUBLIC_NETWORK_ICON_DARK | `string` | Network icon for dark color mode; if not provided, **inverted** regular icon will be used instead | - | - | `https://placekitten.com/60/60` |
| NEXT_PUBLIC_FEATURED_NETWORKS | `string` | URL of configuration file (`.json` format only) which contains list of featured networks that will be shown in the network menu. See [below](#featured-network-configuration-properties) list of available properties for particular network | - | - | `https://example.com/featured_networks_config.json` |
| NEXT_PUBLIC_OTHER_LINKS | `Array<{url: string; text: string}>` | List of links for the "Other" navigation menu | - | - | `[{'url':'https://blockscout.com','text':'Blockscout'}]` |

#### Featured network configuration properties

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| title | `string` | Displayed name of the network | Required | - | `Gnosis Chain` |
| url | `string` | Network explorer main page url | Required | - | `https://blockscout.com/xdai/mainnet` |
| group | `Mainnets \| Testnets \| Other` | Indicates in which tab network appears in the menu | Required | - | `Mainnets` |
| icon | `string` | Network icon; if not provided, the common placeholder will be shown; *Note* that icon size should be at least 60px by 60px | - | - | `https://placekitten.com/60/60` |
| isActive | `boolean` | Pass `true` if item should be shonw as active in the menu | - | - | `true` |
| invertIconInDarkMode | `boolean` | Pass `true` if icon colors should be inverted in dark mode | - | - | `true` |

&nbsp;

### Footer

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_FOOTER_LINKS | `string` | URL of configuration file (`.json` format only) which contains list of link groups to be displayed in the footer. See [below](#footer-links-configuration-properties) list of available properties for particular group | - | - | `https://example.com/footer_links_config.json` |

The app version shown in the footer is derived from build-time ENV variables `NEXT_PUBLIC_GIT_TAG` and `NEXT_PUBLIC_GIT_COMMIT_SHA` and cannot be overwritten at run-time.

#### Footer links configuration properties

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| title | `string` | Title of link group | Required | - | `Company` |
| links | `Array<{'text':string;'url':string;}>` | list of links | Required | - | `[{'text':'Homepage','url':'https://www.blockscout.com'}]` |

&nbsp;

### Favicon

By default, the app has generic favicon. You can override this behavior by providing the following variables. Hence, the favicon assets bundle will be generated at the container start time and will be used instead of default one.

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_FAVICON_GENERATOR_API_KEY | `string` | RealFaviconGenerator [API key](https://realfavicongenerator.net/api/) | Required | - | `<your-secret>` |
| NEXT_PUBLIC_FAVICON_MASTER_URL | `string` | - | - | `NEXT_PUBLIC_NETWORK_ICON` | `https://placekitten.com/180/180` |

&nbsp;

### Views

#### Block views

| Variable | Type | Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_VIEWS_BLOCK_HIDDEN_FIELDS | `Array<BlockFieldId>` | Array of the block fields ids that should be hidden. See below the list of the possible id values. | - | - | `'["burnt_fees","total_reward"]'` |


##### Block fields list
| Id | Description |
| --- | --- |
| `burnt_fees` | Burnt fees |
| `total_reward` | Total block reward |
| `nonce` | Block nonce |

&nbsp;

### Misc

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_NETWORK_EXPLORERS | `Array<NetworkExplorer>` where `NetworkExplorer` can have following [properties](#network-explorer-configuration-properties) | Used to build up links to transactions, blocks, addresses in other chain explorers. | - | - | `[{'title':'Anyblock','baseUrl':'https://explorer.anyblock.tools','paths':{'tx':'/ethereum/poa/core/tx'}}]` |
| NEXT_PUBLIC_HIDE_INDEXING_ALERT | `boolean` | Set to `true` to hide indexing alert, if the chain indexing isn't completed | - | `false` | `true` |

#### Network explorer configuration properties

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| title | `string` | Displayed name of the explorer | Required | - | `Anyblock` |
| baseUrl | `string` | Base url of the explorer | Required | - | `https://explorer.anyblock.tools` |
| paths | `Record<'tx' \| 'block' \| 'address' \| 'token', string>` | Map of explorer entities and their paths | Required | - | `{'tx':'/ethereum/poa/core/tx'}` |

*Note* The url of an entity will be constructed as `<baseUrl><paths[<entity-type>]><entity-id>`, e.g `https://explorer.anyblock.tools/ethereum/poa/core/tx/<tx-id>`

&nbsp;

## App features

*Note* The variables which are marked as required should be passed as described in order to enable the particular feature, but there are not required in the whole app context.

### My account

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_IS_ACCOUNT_SUPPORTED | `boolean` | Set to true if network has account feature | Required | - | `true` |
| NEXT_PUBLIC_AUTH0_CLIENT_ID | `string` | Client id for [Auth0](https://auth0.com/) provider | Required | - | `<your-secret>` |
| NEXT_PUBLIC_AUTH_URL | `string` | Account auth base url; it is used for building login URL (`${ NEXT_PUBLIC_AUTH_URL }/auth/auth0`) and logout return URL (`${ NEXT_PUBLIC_AUTH_URL }/auth/logout`); if not provided the base app URL will be used instead | Required | - | `https://blockscout.com` |
| NEXT_PUBLIC_LOGOUT_URL | `string` | Account logout url. Required if account is supported for the app instance. | Required | - | `https://blockscoutcom.us.auth0.com/v2/logout` |

&nbsp;

### Address verification in "My account"

*Note* all ENV variables required for [My account](ENVS.md#my-account) feature should be passed along side with the following ones:

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_CONTRACT_INFO_API_HOST | `string` | Contract Info API endpoint url | Required | - | `https://contracts-info.services.blockscout.com` |
| NEXT_PUBLIC_ADMIN_SERVICE_API_HOST | `string` | Admin Service API endpoint url | Required | - | `https://admin-rs.services.blockscout.com` |

&nbsp;

### Blockchain interaction (writing to contract, etc.)

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_WALLET_CONNECT_PROJECT_ID | `string` | Project id for [WalletConnect](https://docs.walletconnect.com/2.0/web3modal/react/installation#obtain-project-id) integration | Required | - | `<your-secret>` |
| NEXT_PUBLIC_NETWORK_RPC_URL | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | - | `https://core.poa.network` |
| NEXT_PUBLIC_NETWORK_NAME | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | - | `Gnosis Chain` |
| NEXT_PUBLIC_NETWORK_ID | `number` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | -  | `99` |
| NEXT_PUBLIC_NETWORK_CURRENCY_NAME | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | - | `Ether` |
| NEXT_PUBLIC_NETWORK_CURRENCY_SYMBOL | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | - | `ETH` |
| NEXT_PUBLIC_NETWORK_CURRENCY_DECIMALS | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | - | `18` | `6` |

&nbsp;

### Banner ads

This feature is **enabled by default** with the `slise` ads provider. To switch it off pass `NEXT_PUBLIC_AD_BANNER_PROVIDER=none`.

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_AD_BANNER_PROVIDER | `slise` \| `adbutler` \| `coinzilla` \| `none` | Ads provider  | - | `slise` | `coinzilla` |
| NEXT_PUBLIC_AD_ADBUTLER_CONFIG_DESKTOP | `{ id: string; width: string; height: string }` | Placement config for desktop Adbutler banner | - | - | `{'id':'123456','width':'728','height':'90'}` |
| NEXT_PUBLIC_AD_ADBUTLER_CONFIG_MOBILE | `{ id: string; width: number; height: number }` | Placement config for mobile Adbutler banner | - | - | `{'id':'654321','width':'300','height':'100'}` |

&nbsp;

### Text ads

This feature is **enabled by default** with the `coinzilla` ads provider. To switch it off pass `NEXT_PUBLIC_AD_TEXT_PROVIDER=none`.

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_AD_TEXT_PROVIDER | `coinzilla` \| `none` | Ads provider | - | `coinzilla` | `none` |

&nbsp;

### Beacon chain

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_HAS_BEACON_CHAIN | `boolean` | Set to true for networks with the beacon chain | Required | - | `true` |
| NEXT_PUBLIC_BEACON_CHAIN_CURRENCY_SYMBOL | `string` | Beacon network currency symbol | - | `NEXT_PUBLIC_NETWORK_CURRENCY_SYMBOL` | `ETH` |

&nbsp;

### Rollup (L2) chain

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_IS_L2_NETWORK | `boolean` | Set to true for L2 solutions | Required | - | `true` |
| NEXT_PUBLIC_L1_BASE_URL | `string` | Blockscout base URL for L1 network | Required | - | `'http://eth-goerli.blockscout.com'` |
| NEXT_PUBLIC_L2_WITHDRAWAL_URL | `string` | URL for L2 -> L1 withdrawals | Required | - | `https://app.optimism.io/bridge/withdraw` |

&nbsp;

### Export data to CSV file

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_RE_CAPTCHA_APP_SITE_KEY | `string` | See [below](ENVS.md#google-recaptcha) | true | - | `<your-secret>` |

&nbsp;

### Google analytics

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_GOOGLE_ANALYTICS_PROPERTY_ID | `string` | Property ID for [Google Analytics](https://analytics.google.com/) service | true | - | `UA-XXXXXX-X` |

&nbsp;

### Mixpanel analytics

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_MIXPANEL_PROJECT_TOKEN | `string` | Project token for [Mixpanel](https://mixpanel.com/) analytics service | true | - | `<your-secret>` |

&nbsp;

### GraphQL API documentation

This feature is **always enabled**, but you can configure its behavior by passing the following variables.

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_GRAPHIQL_TRANSACTION | `string` | Txn hash for default query at GraphQl playground page | - | - | `0x4a0ed8ddf751a7cb5297f827699117b0f6d21a0b2907594d300dc9fed75c7e62` |

&nbsp;

### REST API documentation

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_API_SPEC_URL | `string` | Spec to be displayed on `/api-docs` page | Required | `https://raw.githubusercontent.com/blockscout/blockscout-api-v2-swagger/main/swagger.yaml` | `https://raw.githubusercontent.com/blockscout/blockscout-api-v2-swagger/main/swagger.yaml` |

&nbsp;

### Marketplace

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_MARKETPLACE_CONFIG_URL | `string` | URL of configuration file (`.json` format only) which contains list of apps that will be shown on the marketplace page. See [below](#marketplace-app-configuration-properties) list of available properties for an app | Required | - | `https://example.com/marketplace_config.json` |
| NEXT_PUBLIC_MARKETPLACE_SUBMIT_FORM | `string` | Link to form where authors can submit their dapps to the marketplace | Required | - | `https://airtable.com/shrqUAcjgGJ4jU88C` |
| NEXT_PUBLIC_NETWORK_RPC_URL | `string` | See in [Blockchain parameters](ENVS.md#blockchain-parameters) section | Required | - | `https://core.poa.network` |

#### Marketplace app configuration properties

| Property | Type | Description | Compulsoriness | Example value
| --- | --- | --- | --- | --- |
| id | `string` | Used as slug for the app. Must be unique in the app list. | Required | `'app'` |
| external | `boolean` | `true` means that the application opens in a new window, but not in an iframe. | - | `true` |
| title | `string` | Displayed title of the app. | Required | `'The App'` |
| logo | `string` | URL to logo file. Should be at least 288x288. | Required | `'https://foo.app/icon.png'` |
| shortDescription | `string` | Displayed only in the app list. | Required | `'Awesome app'` |
| categories | `Array<MarketplaceCategoryId>` | Displayed category. Select one of the following bellow. | Required | `['security', 'tools']` |
| author | `string` | Displayed author of the app | Required | `'Bob'` |
| url | `string` | URL of the app which will be launched in the iframe. | Required | `'https://foo.app/launch'` |
| description | `string` | Displayed only in the modal dialog with additional info about the app. | Required | `'The best app'` |
| site | `string` | Displayed site link | - | `'https://blockscout.com'` |
| twitter | `string` | Displayed twitter link | - | `'https://twitter.com/blockscoutcom'` |
| telegram | `string`  | Displayed telegram link | - | `'https://t.me/poa_network'` |
| github | `string` | Displayed github link | - | `'https://github.com/blockscout'` |

#### Marketplace categories ids

For each application, you need to specify the `MarketplaceCategoryId` to which it belongs. Select one of the following:

- `defi`
- `exchanges`
- `finance`
- `games`
- `marketplaces`
- `nft`
- `security`
- `social`
- `tools`
- `yieldFarming`

&nbsp;

### Solidity to UML diagrams

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_VISUALIZE_API_HOST | `string` | Visualize API endpoint url | Required | - | `https://visualizer.services.blockscout.com` |

&nbsp;

### Blockchain statistics

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_STATS_API_HOST | `string` | API endpoint url | Required | - | `https://stats.services.blockscout.com` |

&nbsp;

### Web3 wallet integration (add token or network to the wallet)

This feature is **enabled by default** with the `['metamask']` value. To switch it off pass `NEXT_PUBLIC_WEB3_WALLETS=none`.

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_WEB3_WALLETS | `Array<'metamask' \| 'coinbase' \| 'token_pocket'>` | Array of Web3 wallets which will be used  to add tokens or chain to. The first wallet which is enabled in user's browser will be shown. | - | `[ 'metamask' ]` | `[ 'coinbase' ]` |
| NEXT_PUBLIC_WEB3_DISABLE_ADD_TOKEN_TO_WALLET | `boolean`| Set to `true` to hide icon "Add to your wallet" next to token addresses | - | - | `true` |

&nbsp;

### Verified tokens info

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_CONTRACT_INFO_API_HOST | `string` | Contract Info API endpoint url | Required | - | `https://contracts-info.services.blockscout.com` |

&nbsp;

### Sentry error monitoring

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_SENTRY_DSN | `string` | Client key for your Sentry.io app | Required | - | `<your-secret>` |
| SENTRY_CSP_REPORT_URI | `string` | URL for sending CSP-reports to your Sentry.io app | - | - | `<your-secret>` |
| NEXT_PUBLIC_APP_ENV | `string` | Current app env (e.g development, review or production). Passed as `environment` property to Sentry config | - | `process.env.NODE_ENV` | `production` |
| NEXT_PUBLIC_APP_INSTANCE | `string` | Name of app instance. Used as custom tag `app_instance` value in the main Sentry scope | - | - | `wonderful_kepler` |

&nbsp;

## External services configuration

### Google ReCaptcha

For obtaining the variables values please refer to [reCAPTCHA documentation](https://developers.google.com/recaptcha).

| Variable | Type| Description | Compulsoriness  | Default value | Example value |
| --- | --- | --- | --- | --- | --- |
| NEXT_PUBLIC_RE_CAPTCHA_APP_SITE_KEY | `string` | Site key | - | - | `<your-secret>` |
