> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# op-batcher

> Canonical hub for op-batcher, the OP Stack batch submitter — what it does, who runs it, and where its guides, reference, releases, source, and spec live.

op-batcher is the OP Stack's batch submitter: the service that makes an L2
chain's transaction data available by posting it to the data availability
layer.

## Overview

op-batcher reads unsafe blocks from the sequencer, compresses them into
channels, splits the channels into frames, and submits those frames to the
data availability layer — as Ethereum calldata or blob transactions, or via
an [Alt-DA](/op-stack/features/experimental/alt-da-mode) layer. It can also
select between calldata and blobs automatically based on current L1 prices.

It exists because an OP Stack chain is *derived* from the data availability
layer: until op-batcher posts a block's data, verifier nodes cannot derive it
and the chain's safe head does not advance. Batches must also land within the
chain's sequencing window — see the
[batcher guide](/chain-operators/guides/configuration/batcher) for the policy
constraints.

**Who runs it:** the chain operator, as part of the sequencer's
infrastructure, submitting from the chain's batch submitter address. During
data availability backlogs, op-batcher can also instruct the block builder to
throttle how much DA-consuming data new L2 blocks include.

## Get started

* [Spin up batcher](/chain-operators/tutorials/create-l2-rollup/op-batcher-setup)
  — set up and configure op-batcher as part of standing up an OP Stack
  chain.

## How-tos

* [Configure the batcher](/chain-operators/guides/configuration/batcher) —
  batcher policy, cost tuning, multi-blob transactions, and sequencer
  throttling.
* [Using Blobs](/chain-operators/guides/features/blobs) — switch the chain's
  data availability type to blobs.
* [Enable span batches](/chain-operators/guides/features/enable-span-batches)
  — configure the batch type on op-batcher.
* [How to run an Alt-DA mode chain](/chain-operators/guides/features/alt-da-mode-guide)
  — post data to an Alt-DA layer instead of Ethereum.

## Configuration & flags reference

* [Batcher configuration reference](/chain-operators/reference/batcher-configuration)
  — every CLI flag and environment variable, with defaults. The reference
  page states the release it was written against.

## Releases

* [op-batcher release history](/releases/op-batcher)

## Source & spec links

* [Source: `op-batcher/`](https://github.com/ethereum-optimism/optimism/tree/develop/op-batcher)
  in the Optimism monorepo — its [README](https://github.com/ethereum-optimism/optimism/blob/develop/op-batcher/readme.md)
  documents the internal architecture and design principles.
* [DA throttling deep-dive](https://github.com/ethereum-optimism/optimism/blob/develop/op-batcher/throttling.md)
  — in-repo documentation of the throttling controllers (step, linear,
  quadratic, and PID), their configuration, and runtime management over
  RPC.
* [Batch submitter specification](https://specs.optimism.io/protocol/batcher.html)
  — the normative definition of the batcher's role.