cardano-api

cardano-api is the Haskell library for writing applications that interact with the Cardano blockchain. It lets you build and sign transactions, manage keys and addresses, query a running node, and convert between the formats used on Cardano (CBOR, JSON, bech32).

It is the same layer that cardano-cli and cardano-node are built on. Under the hood it combines the ledger, consensus and networking libraries, and hides most of their details behind a single module: Cardano.Api.

What is in this repository

Requirements

You can build with Nix (easiest: it provides everything) or with your own Haskell toolchain.

With Nix:

• Nix with flakes enabled.
• Answer "yes" when Nix asks to accept the flake settings. That enables the IOG binary cache (cache.iog.io). Without it, you will compile GHC and every dependency from source.
• Works on x86_64-linux, aarch64-linux and aarch64-darwin.

Without Nix:

The Developer Portal's Installing cardano-node guide covers this exact setup step by step. Follow it up to the point where it starts building the node itself. In short, you need:

• GHC 9.6, 9.10, 9.12 or 9.14, and Cabal 3.16 (for example via GHCup). Development mostly happens on GHC 9.12.
• Cardano's C libraries: libsodium (the IOG fork, with VRF support), libsecp256k1 and libblst. Prebuilt packages are on the iohk-nix releases page; this GitHub action shows how CI installs them.
• A few common system packages; on Ubuntu: libsystemd-dev liblmdb-dev liburing-dev libsnappy-dev protobuf-compiler.

Quick start

git clone https://github.com/IntersectMBO/cardano-api
cd cardano-api
nix develop          # skip this line if you are not using Nix
cabal update         # needed at least once, see note below
cabal build all --enable-tests

Run the tests:

cabal test all --enable-tests --test-show-details=direct

Build notes:

• cabal update downloads the package lists of two repositories: Hackage and CHaP (Cardano Haskell Packages, where the Cardano-specific dependencies live). CHaP is already configured in this repo's cabal.project.
• The project builds with -Werror, so every warning is an error. Stick to the GHC versions listed above.
• Other Nix shells: nix develop .#ghc967 and .#ghc914 (other compilers, x86_64-linux only), .#profiling, .#wasm (WebAssembly toolchain) and .#demo (Elm toolchain for the browser demo).
• To build the WebAssembly module, see cardano-wasm/README.md.

Using the library in your project

cardano-api is released on CHaP, not on Hackage, so your project needs CHaP configured. A minimal project is three files:

cabal.project points at your package and registers CHaP:

packages: .

repository cardano-haskell-packages
  url: https://chap.intersectmbo.org/
  secure: True
  root-keys:
    3e0cce471cf09815f930210f7827266fd09045445d65923e6d0238a6cd15126f
    443abb7fb497a134c343faf52f0b659bd7999bc06b7f63fa76dc99d631f9bea1
    a86a1f6ce86c449c46666bda44268677abf29b5b2d2eb5ec7af903ec2f117a82
    bcec67e8e99cabfa7764d75ad9b158d72bfacf70ca1d0ec8bc6b4406d1bf8413
    c00aae8461a256275598500ea0e187588c35a5d5d7454fb57eac18d9edb86a56
    d4a35cd3121aa00d18544bb0ac01c3e1691d618f462c46129271bccf39f7e8ee

(Tip: also pin an index-state to make your builds reproducible; see the CHaP README.)

example.cabal:

cabal-version: 3.0
name:          example
version:       0.1.0.0
build-type:    Simple

executable example
  main-is:          Main.hs
  default-language: Haskell2010
  build-depends:
    , base
    , cardano-api ^>=11.5
    , text

Main.hs creates a key and prints a fresh mainnet address. No running node needed:

module Main where

import Cardano.Api

import qualified Data.Text.IO as Text

main :: IO ()
main = do
  -- Make a new payment key.
  signingKey <- generateSigningKey AsPaymentKey
  -- Hash its verification (public) key.
  let keyHash = verificationKeyHash (getVerificationKey signingKey)
      -- Build a mainnet address that pays to that key, with no stake part.
      address = makeShelleyAddress Mainnet (PaymentCredentialByKey keyHash) NoStakeAddress
  Text.putStrLn (serialiseAddress address)

Run it with cabal update && cabal run. It prints a mainnet address (it starts with addr1). Expect the first build to take a while: it compiles the whole Cardano stack. Without Nix, you also need the C libraries from Requirements.

Where to go next:

• The Cardano.Api.Tx haddocks contain worked examples for building, balancing and signing transactions.
• The test suite doubles as a set of small examples: Test.Cardano.Api.Envelope reads and writes key files, Test.Cardano.Api.Address turns keys into addresses, and Test.Cardano.Api.Experimental builds and balances transactions with protocol parameters.
• To talk to a live node from Haskell, look at Cardano.Api.Network.IPC (queries and transaction submission over the node's local socket).
• Cardano.Api.Experimental is a newer transaction-building API that will replace parts of the current one. It is usable, but still changing.

Documentation

• Haddock documentation: the full API reference, rebuilt from master.
• Cardano Node Wiki: development documentation.
• Browser wallet demo: built on cardano-wasm.
• Cardano Developer Portal: if you are new to Cardano itself.

Contributing

See the Contributing guide for how to contribute to this project.

Core maintainers

• Jordan Millar
• Mateusz Gałażyn
• Pablo Lamela