A proposal to modify Bitcoin Core and expand the capacity of OP_Return outputs has sparked debate among developers. The initiative, aiming to remove arbitrary limits and maintain a standard output form, has faced objections from some community members.
The proposal, submitted by Bitcoin Core developer Todd Zotterell, focuses on two main points. Firstly, it calls for removing the configuration settings -datacarrier and -datacarriersize, which currently restrict how much data users can include in an OP_Return output.
These limits, meant to protect the network from spam, are mostly symbolic as protocols and users have found ways to bypass them. For instance, Marathon Digital’s Slipstream allows clients to submit transactions directly to miners, bypassing public mempools and ignoring the standard size limits.
Moreover, Libre Rpay, a fork of Bitcoin Core maintained by Blockstream, removes these enforcement rules completely. This allows projects like BRC-20 tokens to push more data without constraint, simply by using alternative infrastructure. Some protocols also sidestep OP_Return entirely—storing data in unspendable outputs or scriptsigs instead.
In Zotterell’s view, it makes more sense to acknowledge this reality and let Bitcoin Core catch up to the way the network already works. The proposal keeps the form of datacarrier outputs standardized: a single OP_Return followed by zero or more data pushes.
This proposal comes as Bitcoin saw a record number of non-financial transactions in Q1 2024, many of them using OP_Return-like mechanisms to carry data. With the rise of Ordinals and BRC-20 tokens, there's been a surge in on-chain activity, pushing the boundaries of what Bitcoin can do.
