Blockfrost

Blockfrost is a hosted provider: it runs the cardano-node and indexer for you and serves the chain over a REST API, so you can put it under your SDK (or call it directly) without running any infrastructure. It is the quickest backend to start with, has a free tier, and its core is open source. For where it sits among the alternatives, see Choosing a provider.

Create an account and project

Create a free account at blockfrost.io.

After signing in, create a project: click + ADD PROJECT, name it, select the network (mainnet, preprod, or preview), and SAVE. Each project is scoped to one network and gets its own project_id, which is your API key.

warning

Keep your project_id secret. Never commit it or embed it in client-side code. Store it in an environment variable on your backend so it cannot leak to users.

Cardano networks

Each network has its own endpoint and its own project_id:

Network	Endpoint
Cardano mainnet	https://cardano-mainnet.blockfrost.io/api/v0/
Cardano preprod testnet	https://cardano-preprod.blockfrost.io/api/v0/
Cardano preview testnet	https://cardano-preview.blockfrost.io/api/v0/

Your first request

Blockfrost is REST: you authenticate with the project_id header and request an endpoint. Most apps reach it through an SDK's Blockfrost provider (see Query the chain), but you can call it directly:

curl

export BLOCKFROST_PROJECT_ID_MAINNET=mainnet...
curl -H "project_id: $BLOCKFROST_PROJECT_ID_MAINNET" https://cardano-mainnet.blockfrost.io/api/v0/blocks/latest

JavaScript

import { BlockFrostAPI } from "@blockfrost/blockfrost-js";

const API = new BlockFrostAPI({ projectId: "YOUR_PROJECT_ID" });

const latestBlock = await API.blocksLatest();
console.log(latestBlock);

A successful call returns JSON:

{
  "time": 1641338934,
  "height": 15243593,
  "hash": "4ea1ba291e8eef538635a53e59fddba7810d1679631cc3aed7c8e6c4091a516a",
  "slot": 412162133,
  "epoch": 425,
  "slot_leader": "pool1pu5jlj4q9w9jlxeu370a3c9myx47md5j5m2str0naunn2qnikdy",
  "tx_count": 1,
  "fees": "592661"
}

Blockfrost has official SDKs for 15+ languages (JavaScript, Python, Rust, Go, Java, and more). The full endpoint reference is at blockfrost.dev.

Beyond the Cardano API

• IPFS: Blockfrost also runs an IPFS gateway (https://ipfs.blockfrost.io/api/v0/) for pinning off-chain content such as NFT assets.
• Webhooks: subscribe to on-chain events and receive them via HTTP POST instead of polling, with up to five JSONPath filter conditions per webhook. See the webhooks docs.
• Run your own: the backend (blockfrost-backend-ryo), SDKs, and OpenAPI spec are open source. Run a self-hosted instance from source or the prebuilt Docker image:

docker run --rm --name blockfrost-ryo -p 3000:3000 \
  -e BLOCKFROST_CONFIG_SERVER_LISTEN_ADDRESS=0.0.0.0 \
  -v $PWD/config:/app/config \
  blockfrost/backend-ryo:latest