Glossary / Nodes & software
Signet
- Definition
- Signet is a test network whose blocks are only valid if a designated signer has signed them, which keeps its ten minute block schedule steady instead of erratic.
Specified in BIP-325.
Signet trades permissionless mining for predictability. Bitcoin Core added it in version 0.21.0, released in January 2021, and the public default signet has produced blocks on a roughly ten minute rhythm ever since. If you want to try a wallet, a Lightning channel, or a merchant checkout under conditions that resemble mainnet, this is the network to reach for.
How it works
Signet adds exactly one requirement to bitcoin's normal validity checks: a block must carry a valid signature.
BIP325, written by Karl-Johan Alm and Anthony Towns, defines a signet challenge, which is simply a bitcoin script that the block's solution has to satisfy. The solution is attached to the block's segwit commitment inside the coinbase transaction, so nothing about the block format changes and existing software can parse a signet block without modification. Proof of work is still performed, but at a low difficulty, because the signature rather than the hash rate decides when a block counts.
Since the challenge is an ordinary script, it can be anything from a single public key to a threshold multisig. The public default signet, the one you join by passing the signet option with no further configuration, is operated by those two authors under a 1-of-2 multisig, and it listens on port 38333. Addresses reuse testnet's prefixes, so a wallet that already understands tb1 strings usually handles signet with no changes at all.
Anyone can start a private one. Passing a custom challenge script creates a separate network whose message magic is derived from that script, which means two custom signets cannot accidentally talk to each other. That is the feature that separates signet from every other option: you get a genuine multi-participant network with several machines and real propagation delays, without asking anyone's permission and without buying mining hardware.
Where you see it
Signet is where new consensus features get exercised in public before mainnet ever sees them.
Taproot was live on the default signet well before it activated on mainnet at block 709,632 in November 2021, which is a large part of why wallets could ship taproot support at activation rather than months later. The same pattern repeats with each proposal that reaches implementation: the code runs somewhere people can break it cheaply first.
Custom signets have found uses of their own. Mutinynet is a public one that produces a block every 30 seconds, built so Lightning developers do not spend their working day waiting for confirmations. Others exist to rehearse specific scenarios, since whoever holds the signing key can also produce a deliberate reorganization on demand and watch what wallets do about it.
For someone buying bitcoin, signet is invisible and still relevant. Faucets give the coins away, so nothing on this network has value, but the release of Sparrow, Core, or a Lightning node you install was almost certainly put through it first.
Signet vs regtest
Signet is a shared network with strangers on it; regtest is a chain that exists only inside your own computer. On regtest you mine blocks yourself with a single command and can conjure a hundred confirmations in a second. On signet you wait for the signers like everyone else, your transactions propagate through peers you do not control, and fee estimation behaves the way it does on mainnet. Regtest answers whether your code runs; signet answers whether it survives contact with a network.