Providers

A Provider is an abstraction of a connection to the Ethereum network, providing a concise, consistent interface to standard Ethereum node functionality.

The ethers.js library provides several options which should cover the vast majority of use-cases, but also includes the necessary functions and classes for sub-classing if a more custom configuration is necessary.

Most users should use the Default Provider.

Default Provider

The default provider is the safest, easiest way to begin developing on Ethereum, and it is also robust enough for use in production.

It creates a FallbackProvider connected to as many backend services as possible. When a request is made, it is sent to multiple backends simultaneously. As responses from each backend are returned, they are checked that they agree. Once a quorum has been reached (i.e. enough of the backends agree), the response is provided to your application.

This ensures that if a backend has become out-of-sync, or if it has been compromised that its responses are dropped in favor of responses that match the majority.

ethers.getDefaultProvider( [ network , [ options ] ] ) Provider

Returns a new Provider, backed by multiple services, connected to network. If no network is provided, homestead (i.e. mainnet) is used.

The network may also be a URL to connect to, such as http://localhost:8545 or wss://example.com.

The options is an object, with the following properties:

PropertyDescription 
alchemyAlchemy API Token 
etherscanEtherscan API Token 
infuraINFURA Project ID or { projectId, projectSecret } 
pocketPocket Network Application ID or { applicationId, applicationSecretKey } 
quorumThe number of backends that must agree (default: 2 for mainnet, 1 for testnets) 
Option Properties 
Note: API Keys

It is highly recommended for production services to acquire and specify an API Key for each service.

The default API Keys used by ethers are shared across all users, so services may throttle all services that are using the default API Keys during periods of load without realizing it.

Many services also have monitoring and usage metrics, which are only available if an API Key is specified. This allows tracking how many requests are being sent and which methods are being used the most.

Some services also provide additional paid features, which are only available when specifying an API Key.

Networks

There are several official common Ethereum networks as well as custom networks and other compatible projects.

Any API that accept a Networkish can be passed a common name (such as "mainnet" or "ropsten") to use that network definition or may specify custom parameters.

Custom ENS Contract

One common reason to specify custom properties for a Network is to override the address of the root ENS registry, either on a common network to intercept the ENS Methods or to specify the ENS registry on a dev network (on most dev networks you must deploy the ENS contracts manually).

Example: Override the ENS registry
const network = { name: "dev", chianId: 1337, ensAddress: customEnsAddress };

Provider Documentation

Provider
Accounts Methods
Blocks Methods
Ethereum Naming Service (ENS) Methods
Logs Methods
Network Status Methods
Transactions Methods
Event Emitter Methods
Inspection Methods
JsonRpcProvider
JsonRpcSigner
JsonRpcUncheckedSigner
Node-Specific Methods
API Providers
EtherscanProvider
InfuraProvider
AlchemyProvider
CloudflareProvider
Other Providers
FallbackProvider
IpcProvider
UrlJsonRpcProvider
Web3Provider
WebSocketProvider
Types
BlockTag
Networkish
Network
Block
Events and Logs
Transactions