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15 Aug 2023

Apibara indexers preview

We are excited to release the first iteration of the Apibara command line tool. This tool is the first step in overhauling the Apibara developer experience to reduce the time needed to build production-grade indexers. This tool enables developers to easily synchronize onchain data with any offchain service they use: from databases like PostgreSQL and MongoDB to any service that accepts webhooks.

Over the past year, we worked with dozens of teams to understand how they consume onchain data and build applications. We learned that all projects are different, so we wanted a tool that enables them to keep using the tools they already know and love.

The new indexers are built on top of the DNA streams and provide a higher-level developer experience for building indexers.

The new CLI is the main entry point to Apibara: use it to run indexers and manage integrations. Installation is as simple as:

curl -sL https://install.apibara.com | bash

Indexers are implemented in Javascript or Typescript. Apibara embeds a Deno runtime to execute the code users provide on each batch of data it receives in the stream. Thanks to Deno, the indexer scripts are self-contained, and you can run them in a single command. Apibara doesn’t require you to manage half a dozen configuration files.

For example, the following code is enough to index all ERC-20 transfers to a PostgreSQL database. Apibara takes care of all the low-level details such as chain reorganizations.

import { hash, uint256 } from "https://esm.run/starknet@5.14";
import { formatUnits } from "https://esm.run/viem@1.4";
const DECIMALS = 18;
const filter = {
// Only request header if any event matches.
header: {
weak: true,
events: [
keys: [
export const config = {
streamUrl: "https://goerli.starknet.a5a.ch",
startingBlock: 800_000,
network: "starknet",
sinkType: "postgres",
sinkOptions: {
tableName: "transfers",
// Transform each batch of data using the function defined in starknet.js.
export default function transform(batch) {
return batch.flatMap(decodeTransfersInBlock);
function decodeTransfersInBlock({ header, events }) {
const { blockNumber, blockHash, timestamp } = header;
return events.map(({ event, receipt }) => {
const { transactionHash } = receipt;
const transferId = `${transactionHash}_${event.index}`;
const [fromAddress, toAddress, amountLow, amountHigh] = event.data;
const amountRaw = uint256.uint256ToBN({ low: amountLow, high: amountHigh });
const amount = formatUnits(amountRaw, DECIMALS);
// Convert to snake_case because it works better with postgres.
return {
network: "starknet-goerli",
symbol: "ETH",
block_hash: blockHash,
block_number: +blockNumber,
block_timestamp: timestamp,
transaction_hash: transactionHash,
transfer_id: transferId,
from_address: fromAddress,
to_address: toAddress,
amount: +amount,
amount_raw: amountRaw.toString(),

After data is streamed and transformed, it’s sent to the downstream integration. As of today, Apibara ships with 4 integrations:

  • PostgreSQL: mirror onchain data to a database table.
  • MongoDB: mirror onchain data to a collection.
  • Webhook: invoke a webhook every time a new block is produced.
  • Parquet: generate datasets from onchain data.

This is just the first step in a new journey for Apibara. Over the following weeks, we will launch the following products:

  • A hosted service where to deploy your indexers. Develop your indexers locally with the tools presented today. When it comes time to deploy to production, we will take care of it.
  • A new testing framework for indexers. Record live data streams and replay them offline to test your transformation step.
  • A Typescript library to help develop type-safe indexers.
  • More integrations. From high-tech databases like ClickHouse to low-tech solutions like Google Sheets, Apibara can integrate with any app.

Head over to the getting started page to learn how to setup and run your first indexer in less than 10 minutes.

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Apibara is the fastest platform to build production-grade indexers that connect onchain data to web2 services.



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