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FAQ

About Engine​

What are the differences between Engine and thirdweb SDKs?​

Engine is a server that manages your backend wallets and how they interact with contracts. This difference unlocks capabilities that thirdweb and other web3 SDKs, including:

  • Management of KMS backend wallets
  • Fine-grained access control with access tokens
  • Transaction parallelization to handle higher throughput per wallet
  • Observability and retries on stuck transactions
  • Webhooks on completed transactions to sync on-chain and off-chain activity

Additionally, Engine is built on top of the thirdweb SDK and has the same capabilities.

Does Engine work with all thirdweb smart contracts?​

Yes. Engine has intuitive interfaces to deploy prebuilt contracts, manage smart wallets, run a marketplace, and more.

Does Engine work with my non-thirdweb smart contracts?​

Yes. Engine can read and write to any EVM contract with low-level API calls, including providing raw calldata. ERC-721 and ERC-1155 APIs can also be used for contracts imported to thirdweb.

Using Engine​

How do I wait until a transaction completes?​

APIs that call contract write methods (i.e. transactions sent from your backend wallets) enqueue an async job and return a corresponding queueId.

On the backend, use webhooks to be notified when a transaction event occurs.

On frontend clients, use websockets:

const socket = new WebSocket(
  "wss://<engine_url>/transaction/status/<queue_id>?token=<session_token>",
);
socket.onmessage = (event) => {
  const res = JSON.parse(event.data);
  console.log("Received data:", JSON.parse(res.result));
};

How do I customize RPC URLs?​

Set the CHAIN_OVERRIDES environment variable to the path to a JSON file or internet-accessible URL. The default value is ./chain-overrides.json if found. See the example format.

Troubleshooting​

Why is Engine unable to connect to my Postgres DB?​

Here are some common troubleshooting tips:

  • Ensure the Postgres DB is running in Docker:
    • In same container, ensure the host in the POSTGRES_CONNECTION_URL is set to localhost.
    • In different container, ensure the host in the POSTGRES_CONNECTION_URL is set to host.docker.internal.
  • Ensure the Postgres DB connection URL and credentials are correct.
  • Ensure the database name exists on the Postgres DB.