Chain Operators
Chain Features
Run an Alt-DA Mode Chain

How to Run an Alt-DA Mode Chain


The Alt-DA Mode feature is a Beta feature of the MIT licensed OP Stack. While it has received initial review from core contributors, it is still undergoing testing and may have bugs or other issues.

This guide provides a walkthrough for chain operators who want to run an Alt-DA Mode chain. See the Alt-DA Mode Explainer for a general overview of this OP Stack configuration. An Alt-DA Mode OP Stack chain enables a chain operator to post and read data to any alternative data availability layer that has built a functioning OP Stack DA Server.


This page includes providers that meet specific inclusion criteria, as outlined below.


You should use at least the following compatible op* versions when running your chain.

For deploying your contracts, use the latest release.

If you are trying to launch an Alt-DA Mode Chain using a custom gas token, follow the contract deployment instructions in our Custom Gas Token docs.

Setup Your DA Server


DA Servers are not built or maintained by Optimism Collective Core Contributors. DA servers are maintained by third parties and run at your own risk. Please reach out to the team who built the DA Server you are trying to run with any questions or issues.

Configure Your op-node

  • Spin up your OP chain as usual but set --altda.enabled=true and point both op-batcher and op-node to the DA server.
  • No configuration changes are required for op-geth or op-proposer.

    --altda.da-server value                                               ($OP_NODE_ALTDA_DA_SERVER)
          HTTP address of a DA Server
    --altda.enabled                    (default: false)                   ($OP_NODE_ALTDA_ENABLED)
          Enable Alt-DA mode
    --altda.verify-on-read             (default: true)                    ($OP_NODE_ALTDA_VERIFY_ON_READ)
          Verify input data matches the commitments from the DA storage service

Configure Your Batcher

  • Set --altda.enabled=true and --altda.da-service=true.
  • Provide the URL for --atlda.da-server=$DA_SERVER_HTTP_URL.
    --altda.da-server value                                               ($OP_BATCHER_ALTDA_DA_SERVER)
          HTTP address of a DA Server
    --altda.da-service                 (default: false)                   ($OP_BATCHER_ALTDA_DA_SERVICE)
          Use DA service type where commitments are generated by the DA server
    --altda.enabled                    (default: false)                   ($OP_BATCHER_ALTDA_ENABLED)
          Enable Alt-DA mode
    --altda.verify-on-read             (default: true)                    ($OP_BATCHER_ALTDA_VERIFY_ON_READ)
          Verify input data matches the commitments from the DA storage service

After completing steps 1-3 above, you will have an Alt-DA mode chain up and running.

Set Your Fee Configuration

  • Chain operators are not posting everything to Ethereum, just commitments, so chain operators will need to determine fee scalars values to charge users. The fee scalar values are network throughput dependent, so values will need to be adjusted by chain operators as needed.

  • Cost structure for Alt-DA Mode: The transaction data is split up into 128kb chunks and then submitted to your DA Layer. Then, 32 byte commitments are submitted (goes to batch inbox address) to L1 for each 128kb chunk. Then, figure out how much that costs relative to the amount of transactions your chain is putting through.

  • Set scalar values inside the deploy config. The example below shows some possible fee scalar values, calculated assuming negligible DA Layer costs, but will need to be adjusted up or down based on network throughput - as a reminder of how to set your scalar values, see this section (opens in a new tab) of the docs.

    // Set in Deploy Config
      "gasPriceOracleBaseFeeScalar": 7663, // Approximate commitment tx base cost
      "gasPriceOracleBlobBaseFeeScalar": 0, // blobs aren't used for submitting the small data commitments

Some initial scalar values must be set early on in the deploy config in Step 2. And then at a later point, chain operators can update the scalar values with an L1 transaction.

For Node Operators (Full and Archive Nodes)

  • Run a DA server as laid out in Step 1
  • Provide the same --altda.enabled=true, --altda.da-server... on op-node as listed in Step 2

Inclusion Criteria

Alt DA teams who want to be featured on this page must meet the following criteria:

  • Functional DA Server (opens in a new tab), maintained in your own repo
  • Supporting detailed documentation, to be referenced here
  • Functioning OP Stack devnet using your DA server with linked configuration, contract addresses, and RPC address

Next Steps