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Blockchain Forks Explained: Soft Fork vs Hard Fork (and What It Means for Your Crypto)

Last updated: 3 July 2026 · By Spencer Li, CFTe

A blockchain fork is when a cryptocurrency’s chain splits into two paths because the network’s software rules changed. A soft fork is backward-compatible: old nodes (computers running the network) still work, so the chain stays as one. A hard fork is not backward-compatible: it creates a permanent new chain, and you end up holding coins on both the old and the new chain. That is the whole thing in two sentences. A soft fork is an upgrade everyone can live with; a hard fork is a divorce. Bitcoin Cash splitting from Bitcoin in 2017 was a hard fork. SegWit on Bitcoin was a soft fork. As a holder, the practical question is simple: a soft fork rarely needs you to do anything, while a hard fork forces a choice (old chain, new chain, or claim both).

Here is what each fork actually is, why developers choose one over the other, and how it affects your holdings and your exchange.

What is a blockchain fork?

Cryptocurrencies like Bitcoin (BTC) and Ethereum (ETH) run on decentralized, open-source software called a blockchain (a shared ledger of transactions that anyone can read and contribute code to). Because it is open-source, the network relies on its community of developers to keep the code current.

A fork is when that chain of data suddenly diverges into two branches. The new branch shares all of the earlier branch’s history, then heads off in its own direction. From the split point on, each branch goes its own way.

Forks happen for many reasons, but they fall into two buckets:

Accidental forks. Thousands of miners (the computers that race to add new blocks) are working at once. Sometimes two of them mine the same block at nearly the same moment. The network resolves this on its own: it keeps building on the longer chain and abandons the shorter one. No drama, no new coin.
Intentional forks. Here the network does not reconverge. Developers deliberately change the protocol (the blockchain’s core rulebook), for example to alter the block size, reduce block time, or test a new consensus algorithm. Intentional forks are the ones worth understanding, and they come in two flavours: soft and hard.

Soft fork vs hard fork: what is the difference?

The whole distinction comes down to one word: compatibility.

A hard fork is a permanent divergence that creates a brand-new chain and makes the old rules invalid on it. Every node has to adopt the new rules to stay on the new chain. Nodes on the two chains can no longer talk to each other. This usually happens when developers simply cannot agree on a proposed change. When it happens, users and miners face a decision: keep running the old software (stay on the legacy chain) or upgrade to the new one. Either way, you now hold coins on both chains. You still own the legacy coin, and you can claim the new chain’s coin. Any node that refuses to upgrade gets kicked off the new main chain, because it cannot process the new consensus rules.

A soft fork is the gentle version. Its changes are backward-compatible with the pre-fork blocks. Blocks created under the new rules are still valid under the old rules, so nodes do not have to upgrade. You can keep running the old software and still take part in the network. Soft forks tighten the rulebook rather than rewrite it, so the community is nudged onto the new rules instead of being forced. If you never update, things keep working and you still interact with everyone who did update.

Here is the side-by-side.

	Soft fork	Hard fork
Compatibility	Backward-compatible (new blocks still valid under old rules)	Not compatible (old and new chains cannot communicate)
Must nodes upgrade?	No, old software still works	Yes, to stay on the new chain
Result	One chain, upgraded	Two permanent chains
New coin created?	No	Yes, holders end up with coins on both chains
Typical use	Routine upgrades and improvements	Major rule changes, or an unresolved community split
Examples	Bitcoin SegWit	Bitcoin Cash, Ethereum Classic

What are the different types of soft forks?

Not all soft forks activate the same way. There are two:

User-activated soft fork (UASF). Nodes agree to switch on the new rules at a specified block height (a point in the chain’s count). Once activated, those nodes enforce the new rules on every block from then on and reject blocks built under the old rules. A UASF only activates once a majority of hash power (mining power) has signalled support. The risk: if a lot of hash power stays on the old version, you can get a replay attack, where a transaction made on one chain also appears on the other.
Miner-activated soft fork (MASF). This one activates at an agreed-upon block number, triggered by nodes and miners at regular intervals, so there is a built-in delay before full activation. MASFs are generally less disruptive than UASFs because they do not interfere with how users create transactions.

Blockchain forks in practice: the real examples

Most coins have an independent developer community responsible for upgrading the network, so forks happen whenever they add features or harden security. Developers can also use a fork to spin off an entirely new currency and ecosystem. The most famous splits:

Event	Type	When	What changed
Bitcoin Cash (BCH)	Hard fork	Mid-2017	Forked from Bitcoin; block size limit raised from 1 MB to 8 MB, later to 32 MB
Ethereum Classic (ETC)	Hard fork	October 2016	A group rejected the new hard-fork rules and kept running the old Ethereum chain, later renamed ETC
Bitcoin SegWit	Soft fork	2017	Segregated Witness restructured transactions without splitting the chain; un-upgraded nodes still participate
Ethereum to Ethash	Soft fork	,	Moved off Bitcoin’s SHA256 algorithm to Ethash via a forward-compatible upgrade

A couple of things to notice from these.

Bitcoin Cash and Ethereum Classic both came from disagreement. BCH split off after the community could not agree on how to upgrade Bitcoin’s software, so the BCH side loosened the restrictions on what you could do. ETC was the opposite reflex: a group that rejected a hard-fork change and chose to keep the old chain alive. Same mechanism, opposite motivations.

SegWit is the instructive one. It was widely assumed that changing Bitcoin’s transaction structure would need a hard fork. The developers found a forward-compatible way to ship it as a soft fork instead, so nodes that never updated still work on the network. That is the pattern: because a hard fork can split the community in two, developers usually try to solve the problem with a soft fork first, and only hard-fork when there is no compatible path.

If a coin you hold goes through a hard fork, this is the knowledge that lets you decide which branch to follow.

How do forks affect a trading platform?

This is the part that touches your money directly. A hard fork can change how you buy, sell, or trade a coin, because it briefly turns one asset into two.

Not every exchange handles this the same way. Some platforms only list coins they consider viable to trade, which means an upcoming hard fork might be unsupported or trading might be disabled entirely while it resolves. Other platforms support all hard forks. A few even let you buy during a fork by giving you access to the funds and the new coin before trading opens elsewhere, which can give you an early read on how the change will hit your portfolio. The practical takeaway: before a known fork, check how your specific platform plans to handle it, because “do nothing and it sorts itself out” is true for a soft fork and not always true for a hard fork.

Where the human edge comes in

Here is the honest bit. Knowing the mechanics of a fork is the easy half, and frankly an AI can recite the soft-vs-hard difference for you in a second. What the textbook will not do is sit you down before a contentious hard fork and ask whether you actually want exposure to a brand-new coin born out of a community that just fractured, or whether the cleaner move for your book is to step aside through the noise and reassess after the dust settles. That call is judgment, sizing, and a bit of psychology under uncertainty. It is the same skill that separates a good trader from a well-read one, and it is the first of the Five Edges no model trades for you.

FAQ

What is the difference between a soft fork and a hard fork?
A soft fork is backward-compatible, so old nodes keep working and the chain stays unified; it is used for routine upgrades. A hard fork is not backward-compatible, so it creates a permanent second chain, and holders end up with coins on both. SegWit was a soft fork; Bitcoin Cash was a hard fork.

Do I get free coins from a hard fork?
Effectively yes. After a hard fork you still hold your original coin on the legacy chain and can claim the new chain’s coin as well, so you hold the asset on both chains. Whether the new coin holds any value is a separate question entirely.

Is Bitcoin Cash a hard fork or a soft fork?
Bitcoin Cash (BCH) is a hard fork. It split from Bitcoin in mid-2017 and raised the block size limit from 1 MB to 8 MB, later to 32 MB.

What is a UASF versus a MASF?
A user-activated soft fork (UASF) switches on new rules at a set block height once a majority of mining power signals support. A miner-activated soft fork (MASF) activates at an agreed block number triggered by miners, with a built-in delay, and is usually less disruptive.

Should I sell before a fork or hold through it?
There is no one answer, and this is not advice. A soft fork rarely requires you to do anything. For a contentious hard fork, the real question is whether you want exposure to a new, untested chain or would rather reduce risk through the event. Check how your exchange handles the fork before deciding.

So, the next time a coin you hold announces a fork, you will know which kind it is and what it asks of you. Would you sell your tokens and buy back after the split, or hold straight through it? Let me know in the comments below.

And if you want the full picture on how blockchains, coins, and DeFi fit together, read the pillar: The Ultimate Guide to Blockchain and Cryptocurrencies.

Want a system instead of more crypto trivia? Grab the free 15-Minute Swing Trading Starter Kit. It is the exact routine I use to scan once a day and trade any market, crypto included, in 15 minutes.

About the author. Spencer Li is the founder of Synapse Trading and a Certified Financial Technician (CFTe) with 15 years of trading across stocks, forex, crypto, commodities, and bonds. His trade log is public, 404 trades, losses left in. He teaches low-risk swing trading in 15 minutes a day, one system for any market.

Education, not financial advice. Synapse Trading is not licensed by MAS to advise on investment products. Trading carries risk of loss; past performance is not indicative of future results.

The Ultimate Guide to Blockchain and Cryptocurrencies (pillar) · What is Bitcoin and how does it work · Proof of work vs proof of stake · How to start trading cryptocurrency