# Lotus JSON-RPC API reference

This is the reference documentation for the Lotus JSON-RPC API.

Both the Lotus Node and the Lotus Miner serve a JSON-RPC API when started. This APIs are used by the lotus and lotus-miners CLI applications to control the running daemons, so all the necessary functionality performed by those applications also exists as API methods.

# Endpoints

The API can be accessed on:

  • http://[api:port]/rpc/v0 - HTTP RPC-API endpoint
  • ws://[api:port]/rpc/v0 - Websocket RPC-API endpoint
  • http://[api:port]/rest/v0/import (PUT only) - REST endpoint for file import (multipart upload). It requires write permissions.

The Lotus Node configures its listen interface and port in its configuration and the Lotus Miner own config file.

# Methods

The JSON-RPC(opens new window) API matches directly the methods defined in the Lotus API package (link to the Go documentation(opens new window) . This is the best place to discover what methods and types exist for the Lotus and the Lotus Miner APIs. For information on how to jump from a Go method definition to the JSON-RPC method see cURL examples below.

# Common methods

Common methods are available in both the Lotus Node API and the Lotus Miner API. The existing common methods are shown here:

https://pkg.go.dev/github.com/filecoin-project/lotus/api?tab=doc#Common(opens new window)

# Lotus Node methods

The following methods are only provided by the Lotus Node API:

https://pkg.go.dev/github.com/filecoin-project/lotus/api?tab=doc#FullNode(opens new window)

# Lotus Miner methods

The following methods are specific to the Lotus Miner API:

https://pkg.go.dev/github.com/filecoin-project/lotus/api?tab=doc#StorageMiner(opens new window)

# API client libraries

Read the Lotus client libraries page for an overview of existing clients.

Lotus uses its own Go library implementation of JSON-RPC(opens new window) . An example on how to use the client side of it is available here.

# cURL examples

To demonstrate making an API request, we will take the method ChainHead from api/api_full.go(opens new window) and create a CURL command. The method is defined as:

ChainHead(context.Context) (*types.TipSet, error)

Thus, ChainHead will translate as the following JSON-RPC(opens new window) request object:

  "jsonrpc": "2.0",
  "method": "Filecoin.ChainHead",
  "params": [],
  "id": 1

Note the id is an arbitrary number.

In order to make a cURL request we will also need an authorization token, which can be easily generated.

curl -X POST \
	 -H "Content-Type: application/json" \
	 -H "Authorization: Bearer $(cat ~/.lotusminer/token)" \
	 --data '{ "jsonrpc": "2.0", "method": "Filecoin.ChainHead", "params": [], "id": 1 }' \

The response will be a JSON object corresponding to the Typset type(opens new window) (which is actually serialized to JSON from the ExpTipSet type(opens new window) ).

Let us now make a request with parameters using the ChainGetMessage method(opens new window) for a message with CID bafy2bzacedcdedrghloawlwkntdhqnknqzxgh26ddwix7ld2a5ygagco3ngee. Per the above, the JSON-RPC request payload will look like:

  "jsonrpc": "2.0",
  "method": "Filecoin.ChainGetMessage",
  "params": [
    { "/": "bafy2bzacedcdedrghloawlwkntdhqnknqzxgh26ddwix7ld2a5ygagco3ngee" }
  "id": 1

Notice how the CID has been serialized (a common pitfall).

The cURL request will then be:

curl -X POST \
	 -H "Content-Type: application/json" \
	 -H "Authorization: Bearer $(cat ~/.lotusminer/token)" \
	 --data '{"jsonrpc":"2.0","method":"Filecoin.ChainGetMessage","params":[{"/":"bafy2bzacedcdedrghloawlwkntdhqnknqzxgh26ddwix7ld2a5ygagco3ngee"}],"id":1}' \

And the response is a JSON-serialized Message type(opens new window)

All the above should help you getting bootstrapped to harness the power of the Lotus APIs!