# JSON-RPC Server
Learn about the JSON-RPC server to interact with the EVM.
# Pre-requisite Readings
# JSON-RPC API
JSON (opens new window) is a lightweight data-interchange format. It can represent numbers, strings, ordered sequences of values, and collections of name/value pairs.
JSON-RPC (opens new window) is a stateless, light-weight remote procedure call (RPC) protocol. Primarily this specification defines several data structures and the rules around their processing. It is transport agnostic in that the concepts can be used within the same process, over sockets, over HTTP, or in many various message passing environments. It uses JSON (RFC 4627 (opens new window)) as data format.
# JSON-RPC Support
Evmos supports all standard web3 JSON-RPC APIs. You can find documentation for these APIs on the
JSON-RPC Methods page.
JSON-RPC is provided on multiple transports. Evmos supports JSON-RPC over HTTP and WebSocket. Transports must be enabled through command-line flags or through the
app.toml configuration file. For more details see the 
Ethereum JSON-RPC APIs use a name-space system. RPC methods are grouped into several categories depending on their purpose. All method names are composed of the namespace, an underscore, and the actual method name within the namespace. For example, the eth_call method resides in the eth namespace.
Access to RPC methods can be enabled on a per-namespace basis. Find documentation for individual namespaces in the Namespaces page.
# HEX value encoding
At present there are two key datatypes that are passed over JSON: unformatted byte arrays and quantities. Both are passed with a hex encoding, however with different requirements to formatting:
When encoding QUANTITIES (integers, numbers): encode as hex, prefix with
"0x", the most compact representation (slight exception: zero should be represented as
0x41(65 in decimal)
0x400(1024 in decimal)
0x(should always have at least one digit - zero is
0x0400(no leading zeroes allowed)
ff(must be prefixed
When encoding UNFORMATTED DATA (byte arrays, account addresses, hashes, bytecode arrays): encode as hex, prefix with
"0x", two hex digits per byte. Examples:
0xf0f0f(must be even number of digits)
004200(must be prefixed
# Default block parameter
The following methods have an extra default block parameter:
When requests are made that act on the state of Evmos, the last default block parameter determines the height of the block.
The following options are possible for the
HEX String- an integer block number
String "earliest"for the earliest/genesis block
String "latest"- for the latest mined block
String "pending"- for the pending state/transactions
# Curl Examples Explained
The curl options below might return a response where the node complains about the content type, this is because the
--data option sets the content type to
application/x-www-form-urlencoded. If your node does complain, manually set the header by placing
-H "Content-Type: application/json" at the start of the call.
The examples also do not include the URL/IP & port combination which must be the last argument given to curl e.x.