To facilitate testing and debugging of ABCI servers and simple apps, we built a CLI, the abci-cli, for sending ABCI messages from the command line.


Make sure you have Go installed.

Next, install the abci-cli tool and example applications:

git clone
cd cometbft
make install_abci

Now run abci-cli to see the list of commands:

  abci-cli [command]

Available Commands:
  batch            run a batch of abci commands against an application
  check_tx         validate a transaction
  commit           commit the application state and return the Merkle root hash
  completion       Generate the autocompletion script for the specified shell
  console          start an interactive ABCI console for multiple commands
  deliver_tx       deliver a new transaction to the application
  echo             have the application echo a message
  help             Help about any command
  info             get some info about the application
  kvstore          ABCI demo example
  prepare_proposal prepare proposal
  process_proposal process proposal
  query            query the application state
  test             run integration tests
  version          print ABCI console version

      --abci string        either socket or grpc (default "socket")
      --address string     address of application socket (default "tcp://")
  -h, --help               help for abci-cli
      --log_level string   set the logger level (default "debug")
  -v, --verbose            print the command and results as if it were a console session

Use "abci-cli [command] --help" for more information about a command.

KVStore - First Example

The abci-cli tool lets us send ABCI messages to our application, to help build and debug them.

The most important messages are deliver_tx, check_tx, and commit, but there are others for convenience, configuration, and information purposes.

We’ll start a kvstore application, which was installed at the same time as abci-cli above. The kvstore just stores transactions in a merkle tree. Its code can be found here and looks like the following:

func cmdKVStore(cmd *cobra.Command, args []string) error {
	logger := log.NewTMLogger(log.NewSyncWriter(os.Stdout))

	// Create the application - in memory or persisted to disk
	var app types.Application
	if flagPersist == "" {
		var err error
		flagPersist, err = os.MkdirTemp("", "persistent_kvstore_tmp")
		if err != nil {
			return err
	app = kvstore.NewPersistentKVStoreApplication(flagPersist)
	app.(*kvstore.PersistentKVStoreApplication).SetLogger(logger.With("module", "kvstore"))

	// Start the listener
	srv, err := server.NewServer(flagAddress, flagAbci, app)
	if err != nil {
		return err
	srv.SetLogger(logger.With("module", "abci-server"))
	if err := srv.Start(); err != nil {
		return err

	// Stop upon receiving SIGTERM or CTRL-C.
	cmtos.TrapSignal(logger, func() {
		// Cleanup
		if err := srv.Stop(); err != nil {
			logger.Error("Error while stopping server", "err", err)

	// Run forever.
	select {}

Start the application by running:

abci-cli kvstore

And in another terminal, run

abci-cli echo hello
abci-cli info

You’ll see something like:

-> data: hello
-> data.hex: 68656C6C6F


-> data: {"size":0}
-> data.hex: 7B2273697A65223A307D

An ABCI application must provide two things:

When we run the abci-cli tool we open a new connection to the application’s socket server, send the given ABCI message, and wait for a response.

The server may be generic for a particular language, and we provide a reference implementation in Golang. See the list of other ABCI implementations for servers in other languages.

The handler is specific to the application, and may be arbitrary, so long as it is deterministic and conforms to the ABCI interface specification.

So when we run abci-cli info, we open a new connection to the ABCI server, which calls the Info() method on the application, which tells us the number of transactions in our Merkle tree.

Now, since every command opens a new connection, we provide the abci-cli console and abci-cli batch commands, to allow multiple ABCI messages to be sent over a single connection.

Running abci-cli console should drop you in an interactive console for speaking ABCI messages to your application.

Try running these commands:

> echo hello
-> code: OK
-> data: hello
-> data.hex: 0x68656C6C6F

> info 
-> code: OK
-> data: {"size":0}
-> data.hex: 0x7B2273697A65223A307D

> prepare_proposal "abc"
-> code: OK
-> log: Succeeded. Tx: abc

> process_proposal "abc"
-> code: OK
-> status: ACCEPT

> commit 
-> code: OK
-> data.hex: 0x0000000000000000

> deliver_tx "abc"
-> code: OK

> info 
-> code: OK
-> data: {"size":1}
-> data.hex: 0x7B2273697A65223A317D

> commit 
-> code: OK
-> data.hex: 0x0200000000000000

> query "abc"
-> code: OK
-> log: exists
-> height: 2
-> key: abc
-> key.hex: 616263
-> value: abc
-> value.hex: 616263

> deliver_tx "def=xyz"
-> code: OK

> commit 
-> code: OK
-> data.hex: 0x0400000000000000

> query "def"
-> code: OK
-> log: exists
-> height: 3
-> key: def
-> key.hex: 646566
-> value: xyz
-> value.hex: 78797A

> prepare_proposal "preparedef"
-> code: OK
-> log: Succeeded. Tx: replacedef

> process_proposal "replacedef"
-> code: OK
-> status: ACCEPT

> process_proposal "preparedef"
-> code: OK
-> status: REJECT

> prepare_proposal 

> process_proposal 
-> code: OK
-> status: ACCEPT

> commit 
-> code: OK
-> data.hex: 0x0400000000000000

Note that if we do deliver_tx "abc" it will store (abc, abc), but if we do deliver_tx "abc=efg" it will store (abc, efg).

You could put the commands in a file and run abci-cli --verbose batch < myfile.

Note that the abci-cli is designed strictly for testing and debugging. In a real deployment, the role of sending messages is taken by CometBFT, which connects to the app using four separate connections, each with its own pattern of messages.

For examples of running an ABCI app with CometBFT, see the getting started guide.


Want to write an app in your favorite language?! We’d be happy to add you to our ecosystem! See funding opportunities from the Interchain Foundation for implementations in new languages and more.

Decorative Orb