Blockfrost

A Blockfrost-compatible REST API for Cardano, hosted by Demeter.

What it is for

Reading chain data over HTTP: blocks, transactions, addresses, UTxOs, assets, protocol parameters, and transaction submission. Any client written for the Blockfrost API works against it once you point it at the Demeter URL. Mesh, Lucid Evolution and Blaze all ship a Blockfrost provider, and @blockfrost/blockfrost-js is the Blockfrost SDK itself.

For the endpoints it serves, see the API reference.

Hosts

The pattern, where {network} is cardano-mainnet, cardano-preprod or cardano-preview:

https://{network}.blockfrost-m1.dmtr.host

On preprod:

https://cardano-preprod.blockfrost-m1.dmtr.host

The authenticated form puts the key in the host:

https://{key}.{network}.blockfrost-m1.dmtr.host

Paths start at the root, so the latest block is /blocks/latest. There is no /api/v0 prefix.

Authentication

Send the key in the dmtr-api-key header:

dmtr-api-key: <your key>

Or use the authenticated host, with no header. Use it with libraries that cannot set a custom header. Mesh, Lucid Evolution and Blaze are all in that group.

Networks

cardano-mainnet, cardano-preprod and cardano-preview. Each port serves one network, chosen when you create it.

Limits

Usage is counted per 100,000 requests, and throughput is capped by requests per second. Minimum fees apply only to the tiers that reserve throughput.

Getting a key

Create a Blockfrost port at https://console.demeter.run. The port's page shows its endpoint, its authenticated endpoint and its API key.

Example

Set the key in your shell:

export DEMETER_API_KEY=...   # the API key from the port's page

With curl, the latest block on preprod:

curl -H "dmtr-api-key: $DEMETER_API_KEY" \
  https://cardano-preprod.blockfrost-m1.dmtr.host/blocks/latest

Mesh

BlockfrostProvider takes a base URL and sends no custom header, so use the authenticated host (checked against @meshsdk/core 1.9.1):

import { BlockfrostProvider } from "@meshsdk/core";

const provider = new BlockfrostProvider(
  `https://${process.env.DEMETER_API_KEY}.cardano-preprod.blockfrost-m1.dmtr.host`,
);

console.log(await provider.fetchLatestBlock());

Lucid Evolution

Blockfrost takes a URL and an optional project id, which it sends as a project_id header. Demeter reads the key from the host, so leave the project id out (checked against @lucid-evolution/lucid 0.8.2):

import { Blockfrost, Lucid } from "@lucid-evolution/lucid";

const provider = new Blockfrost(
  `https://${process.env.DEMETER_API_KEY}.cardano-preprod.blockfrost-m1.dmtr.host`,
);

console.log(await provider.getProtocolParameters());

const lucid = await Lucid(provider, "Preprod");

Blaze

Blaze's Blockfrost provider has no base-URL option: its constructor takes a network name and builds a blockfrost.io URL from it. Its url field is public, and every request reads it, so you can point it at Demeter after construction. The value must end with /. This works as of @blaze-cardano/query 0.6.4, but it is not a documented option, so pin your version:

import { Blockfrost } from "@blaze-cardano/query";

const provider = new Blockfrost({ network: "cardano-preprod", projectId: "" });
provider.url = `https://${process.env.DEMETER_API_KEY}.cardano-preprod.blockfrost-m1.dmtr.host/`;

console.log(await provider.getParameters());