# @api3/chains
> API3 chains
Latest version **11.8.0** (published 2025-02-13) · MIT license · 0 weekly downloads
## Install
```sh
npm install @api3/chains
pnpm add @api3/chains
yarn add @api3/chains
bun add @api3/chains
```
## Health
**Score 40/100 (D)** — status: maintenance-mode.
Positive: has types; no vulnerabilities; has provenance; high quality score.
Warnings: low downloads; no esm support.
Negative: stale; low maintenance score.
## Facts
| | |
|---|---|
| Version | 11.8.0 |
| Published | 2025-02-13 |
| First published | 2023-03-06 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 2 |
| Unpacked size | 243.3 KB |
| Known vulnerabilities | 0 (+1 in 1 direct dependencies) |
| Install scripts | no |
| Provenance | attested (GitHub Actions) |
| GitHub stars | 4 |
| Author | API3 DAO |
| Maintainers | aquarat, dcroote, bbenligiray, siegrift |
## Links
- npm: https://www.npmjs.com/package/@api3/chains
- Repository: https://github.com/api3dao/chains
- Homepage: https://github.com/api3dao/chains#readme
- Issues: https://github.com/api3dao/chains/issues
- npm.io page: https://npm.io/package/@api3/chains
## Dependencies (2)
- [zod](https://npm.io/package/zod.md) ^3.23.8
- [viem](https://npm.io/package/viem.md) ^2.21.29
## Recent versions
- 11.8.0 (latest) — 2025-02-13
- 11.7.0 — 2025-02-12
- 11.6.0 — 2025-02-06
- 11.5.1 — 2025-02-04
- 11.5.0 — 2025-01-15
- 11.4.2 — 2025-01-06
- 11.4.1 — 2025-01-04
- 11.4.0 — 2024-12-19
- 11.3.0 — 2024-12-18
- 11.2.2 — 2024-12-17
- 11.2.1 — 2024-12-17
- 11.2.0 — 2024-12-16
- 11.1.1 — 2024-12-12
- 11.1.0 — 2024-12-11
- 11.0.0 — 2024-12-04
- … 97 more at https://npm.io/package/@api3/chains/versions
## README
API3 chains
[](https://www.npmjs.com/package/@api3/chains)
[](https://github.com/api3dao/chains/actions/workflows/continuous-build.yml)
[](https://github.com/api3dao/chains/actions/workflows/check-providers.yml)
[](https://www.npmjs.com/package/@api3/chains)
The single source of truth for chain-related information across API3 projects
## 📦 Installation
```sh
npm install @api3/chains --save
yarn add @api3/chains
pnpm add @api3/chains
```
## 📖 API
The following variables/functions are exported from this package
### CHAINS
The single source of truth for the list of supported chains.
A static array of `Chain` objects.
```ts
import { CHAINS } from '@api3/chains';
console.log(CHAINS);
/*
[
{
name: 'Arbitrum Sepolia testnet',
alias: 'arbitrum-sepolia-testnet',
id: '421614',
...
},
...
]
*/
```
### hardhatConfig.networks()
Returns an object where the key is each chain's alias and the value is an object that can be used as the `networks` field of [`hardhat.config.js`](https://hardhat.org/hardhat-runner/docs/config).
The default `url` values can be overridden with chain specific environment variables. These environment variables take the form of `HARDHAT_HTTP_RPC_URL_${toUpperSnakeCase(chain.alias)}`. e.g. `HARDHAT_HTTP_RPC_URL_ARBITRUM_SEPOLIA_TESTNET`.
```ts
import { hardhatConfig } from '@api3/chains';
console.log(hardhatConfig.networks());
/*
{
"arbitrum-sepolia-testnet": {
accounts: { mnemonic: '' },
chainId: '421614',
url: 'https://...',
},
...
}
*/
```
### hardhatConfig.etherscan()
Returns an object where the key is each chain's alias and the value is an object that can be used as the `etherscan` field of [`hardhat.config.js`](https://hardhat.org/hardhat-runner/docs/config) (requires the [`hardhat-etherscan` plugin](https://hardhat.org/hardhat-runner/plugins/nomiclabs-hardhat-etherscan)).
NOTE: [hardhat-etherscan](https://www.npmjs.com/package/@nomiclabs/hardhat-etherscan) requires us to use a dummy API key with Blockscout block explorer APIs. We use "DUMMY_VALUE" but it could have been anything else.
```ts
import { hardhatConfig } from '@api3/chains';
console.log(hardhatConfig.etherscan());
/*
{
apiKey: {
'arbitrumSepolia': { ... }
},
customChains: [
...
]
}
*/
```
### hardhatConfig.getEnvVariableNames()
Returns an array of expected environment variable names for chains that have an API key required for the explorer. The array also includes a single `MNEMONIC` variable that can be used to configure all networks.
NOTE: Each `ETHERSCAN_API_KEY_` and `HARDHAT_HTTP_RPC_URL_` environment variable has the chain alias as a suffix, where the alias has been converted to upper snake case.
```ts
import { hardhatConfig } from '@api3/chains';
console.log(hardhatConfig.getEnvVariableNames());
/*
[
'MNEMONIC',
'ETHERSCAN_API_KEY_ARBITRUM_SEPOLIA_TESTNET',
...
'HARDHAT_HTTP_RPC_URL_ARBITRUM_SEPOLIA_TESTNET',
...
]
*/
```
### viemConfig.chains()
Returns an array of chains in the format that [Viem](https://viem.sh/docs/chains/introduction) expects. Each Chain object can be used to [create a Viem public client](https://viem.sh/docs/clients/public#usage).
Additional `rpcUrls` values can (optionally) be added through the use of environment variables. These environment variables take the form of `API3_CHAINS_HTTP_RPC_URL_${toUpperSnakeCase(chain.alias)}`. If a matching environment variable is detected for a given chain, then it will be added to the `http` array of the `rpcUrls.environment` object. If no matching environment variable is detected, then the `http` array is left empty.
```ts
import { viemConfig } from '@api3/chains';
console.log(viemConfig.chains());
/*
[
{
id: 421613,
name: 'arbitrum-sepolia-testnet',
network: 'arbitrum-sepolia-testnet',
rpcUrls: { default: ..., public: ..., environment: ... }
...
},
...
]
*/
```
### Types
Types are also exported and can be found in `src/types.ts`.
Types are generated from [zod](https://github.com/colinhacks/zod) schemas.
These schemas are also used to validate each chain.
## 📄 Scripts
The following utility scripts are available
### generate:chains
Generates the latest `CHAINS` array and outputs the file to `src/generated/chains.ts`
```sh
pnpm generate:chains
```
### providers:ping
Iterates through the list of chains to check that the chain is configured correctly and is responsive.
```sh
pnpm providers:ping
```
## 🛠️ Development
The most common type of change would be adding or updating a chain. This can be done by creating or editing the relevant JSON file in the `chains/` directory.
If any changes are made to chains, you will need to "regenerate" the chains. This will compile all of the JSON files into a single TypeScript file for projects to import. This can be done with the following command
```sh
pnpm generate:chains
```
The list of TypeScript chains is also validated against all of the list of JSON files to ensure that everything is in sync.
NOTE: You will not be able to push changes to chains without having regenerated the TypeScript chains.
### Validation
Validations can be run with the following commands.
```sh
# Validate each chain JSON file conforms to the zod schemas
pnpm validate:chains
# Run all validations
pnpm validate
```
## 🚢 Releasing
Releasing new versions is handled automatically with [changesets](https://github.com/changesets/changesets). Pull requests should include a changeset file before being merged.
These can be generated by running `pnpm changeset` and following the instructions. Once a new version is ready to be released, simply merge `main` into the `production`
branch. Changeset files will be consolidated into a single new version and that version released to npm.
More information is contained in the [API3 guidelines](https://github.com/api3dao/tasks/blob/main/API3%20Packages/changeset.md).
---
_Source: https://npm.io/package/@api3/chains · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._