Bitcoin confirms removal of OP_Return byte limit: Is Bitcoin facing another on-chain governance split?

Yesterday (22), the Bitcoin Core development team officially confirmed that the 80-byte limit on the OP_Return opcode will be removed in version 30.0. Bitcoin developer and advocate Jimmy Song strongly criticized this move by Bitcoin Core, calling it a fundamentally "fiat mindset."

The development team ignores voices from the Bitcoin community and node operators

OP_Return is a special output format in Bitcoin transactions that allows a small amount of data to be written to the blockchain. It is mainly used to store small pieces of information on the Bitcoin blockchain and does not affect Bitcoin’s functionality. However, unlike regular transaction outputs, OP_Return outputs cannot be spent and do not add to the unspent transaction outputs (UTXOs) set.

It can be said that OP_Return enables Bitcoin to be used not only as a currency but also as a tool for data storage and verification. It also provides a foundation for the development of other assets and applications, for example, it was widely used during the Ordinals inscription craze at the beginning of 2024.

OP_Return was proposed by the Bitcoin developer community in 2014. Its original purpose was to allow transactions to safely carry "small amounts of data" into the blockchain, with a typical limit of 40 bytes, which was later increased to 80 bytes in v0.11. The intention behind this feature was to give users the opportunity to leave a short message on the Bitcoin chain (such as proof of ownership, digital file hashes, copyright statements, evidence of artwork, etc.), while avoiding "non-monetary uses" from occupying UTXO space and keeping the ledger clean.

This decision to remove the OP_Return opcode limit has led Jimmy Song to accuse Core developers of dodging user concerns over lifting the OP_Return restriction (currently 80 bytes) and ignoring strong opposition from the Bitcoin community and node operators.

Many opponents worry that if a large amount of non-financial data floods in, the blockchain size will rapidly expand, increasing hardware costs and undermining the foundation that "everyone can run a node."

Song stated: "Claiming that spam is hard to define, and therefore making no distinction in software design, is a wasteful 'political' sophistry. Non-monetary uses of Bitcoin are just spam."

The debate over OP_Return has lasted nearly six months, inevitably reminding the market of the Bitcoin block size debate from 2015 to 2017. That dispute ultimately led to a hard fork of the Bitcoin protocol and the birth of Bitcoin Cash, causing some in the Bitcoin community to speculate whether the OP_Return controversy will also trigger a similar split.

In 2017, the community failed to reach consensus for a long time, eventually leading to a hard fork

From 2015 to 2017, the Bitcoin community was embroiled in fierce debate over the block size limit (1MB), splitting into "big block" and "small block" factions. The former wanted to modify the original Bitcoin protocol to increase block capacity to handle more transactions, arguing that cheaper and faster transactions would make Bitcoin more scalable.

The latter wanted to maintain the 1 MB size limit (Satoshi Nakamoto originally added a clear 1 MB size limit per block, but never publicly explained why), prioritizing Bitcoin’s security and decentralization principles. They believed that increasing the block size would raise the cost for ordinary users to run Bitcoin nodes, leading to enterprises hosting nodes in data centers and harming the network’s decentralization.

After a prolonged inability to reach consensus, a hard fork was the result. On August 1, 2017, the camp supporting block expansion created a new chain, Bitcoin Cash, raising the block limit to 8MB and later to 32MB. BTC (Bitcoin) maintained the original 1MB block limit, shifting towards a "digital gold" and store of value role; BCH focused on "payment applications" and fast, low-fee daily transactions.

This established two major paths: BTC as digital gold (high security, store of value) and BCH as a circulating currency (fast, low fees), directly influencing subsequent Bitcoin governance, protocol disputes, and other fork discussions.

Opponents leave en masse, turning to Bitcoin Knots

Currently, many node operators are turning to Bitcoin Knots, which continues the existing data limits. According to Coin Dance data, the proportion of nodes using Bitcoin Knots has soared from about 1% in 2024 to 20%, showing vertical growth in just nine months. Knots allows node operators to enforce strict data size limits, and supporters believe this is necessary to maintain the decentralization of the Bitcoin protocol.

Since the decentralized protocol was established in 2009, the Bitcoin ledger has generated about 680 GB of data, thanks to Bitcoin’s simple architecture and strict data limits. Bitcoin’s low data storage requirements allow anyone to synchronize about 680 GB of full chain data with retail hardware costing around $300, greatly enabling democratic participation and maximum decentralization.

This time, node operators are resisting with concrete actions, turning en masse to Bitcoin Knots and sparking a historic wave of departures.

Developers supporting the removal of the OP_Return limit argue that the current 80-byte restriction is merely an artificial threshold, and there are already various ways to bypass it, such as using Taproot and Ordinals technology in Bitcoin protocol upgrades to split data and embed it in different parts of a transaction, breaking through the single OP_Return size limit. If data carrying capacity can be increased, it could inspire more innovative applications and support the network’s sustainable development.

This debate over the OP_Return limit highlights the Bitcoin community’s challenge in balancing on-chain data storage space and the principle of decentralization. As technology evolves and use cases diversify, the 80-byte limit can no longer effectively reflect real-world needs. Removing this restriction means the Bitcoin ecosystem will enter a more open and inclusive stage, helping to foster more innovative applications and providing new revenue incentives for miners.

However, this also brings risks of network bloat and decentralization pressure, forcing the community to re-examine how to balance expansion with the protection of core values.