[ANN] ThankBitcoin (TBC) — a Bitcoin Core fork; beneficiary decided by a Bitcoin

[thankbitcoin]

ThankBitcoin (TBC) - a Bitcoin Core fork that outsources one consensus decision to the Bitcoin chain

Experimental / educational protocol research. Not a product, not a company, not a financial instrument. See the disclaimer at the end.

TL;DR: A Bitcoin Core fork where who receives part of each block reward is decided by an open auction on the Bitcoin chain - and that ruling is enforced by Bitcoin's own hashrate. One added consensus rule; everything else is Bitcoin unchanged.

What it is

ThankBitcoin is a fork of Bitcoin Core with exactly one added consensus rule. Everything else - proof of work, the longest-chain rule, the UTXO model, scripts, signatures, addresses - is inherited from Bitcoin unchanged.

The one change: each block's coinbase pays two shares instead of one.

• a miner share (won by PoW, plus all transaction fees), and
• a beneficiary share - paid to an address that is not chosen by ThankBitcoin's own chain, but decided by a public, on-chain competition on the Bitcoin chain.

Why do this

A brand-new PoW chain has almost no hashrate, so its longest-chain rule is weak and its history is cheap to rewrite. ThankBitcoin does not claim to fix that for every transaction (it can't - ordinary blocks still rely on ThankBitcoin's own PoW; we say so plainly). Instead it takes the single most consensus-critical decision on the chain - who receives the beneficiary share - and hands the ruling to Bitcoin's hashrate. The competition result is written into a Bitcoin transaction; once that transaction has enough confirmations, changing the result would mean reorganizing Bitcoin itself.


How the competition works

Time is divided into terms of 1000 blocks each. Within one term the beneficiary is fixed. To become the beneficiary of the next term, you broadcast a specially-structured transaction on the Bitcoin chain:

Code:

   A qualifying bid = one Bitcoin transaction, 4 outputs:

   inputs: your BTC --+
                      |
                      +-> vout[0]  bid amount   --> fixed recipient (bitcoin.org donation addr)
                      |                              the higher the bid, the better your rank
                      |
                      +-> vout[1]  >= dust       --> previous term's beneficiary
                      |                              (links the term history, anyone can trace)
                      |
                      +-> vout[2]  change        --> back to you
                      |
                      +-> vout[3]  OP_RETURN 52B --> [ 32B: prev ThankBitcoin block hash | 20B: ThankBitcoin payout addr ]
                                                     binds the bid to THIS round (no replay)

• output 0 - your bid, a real Bitcoin transfer to a fixed recipient address (the public bitcoin.org donation address). Making the bid a real transfer is what makes bidding costly and sybil-resistant.
• output 1 - a small linking output to the previous term's beneficiary; chains term history together, verifiable by anyone scanning Bitcoin.
• output 3 - the only data output: the previous term's last ThankBitcoin block hash (binds the bid to this round, prevents replay) followed by the 20-byte hash of the address you want to receive the ThankBitcoin beneficiary share.

The rule for picking the winner is a deterministic pure function of the Bitcoin chain, so any two nodes with the same Bitcoin view compute the same result:

• Scan the Bitcoin chain from the term's start height upward.
• The decisive block B* is the first block that (a) contains at least one qualifying bid and (b) has at least 8 confirmations.
• Inside B*, the highest bid wins (ties broken deterministically by txid).

No bidders? A fallback, not a stall. Each term opens a grace window that starts at the term-boundary anchor and lasts until a Bitcoin block ~8 confirmations deep has appeared (so bidders get real on-chain time). If no qualifying bid shows up in that window, the term falls back: the beneficiary share is paid to a provably-unspendable burn address (all-zero HASH160 - no private key can exist for it, anyone can verify), not carried over to the previous beneficiary. This removes any incentive to manufacture a "no-bid" term to keep collecting - nobody can collect. The chain keeps producing blocks normally.

Note - two different addresses, don't confuse them: the bid recipient (output 0 above) is a real, spendable address on the Bitcoin chain (the bitcoin.org donation address); the fallback burn address is an all-zero address on the ThankBitcoin chain that provably has no private key. Bids are real Bitcoin transfers; fallback shares are ThankBitcoin coins that can never be spent (effectively destroyed).

Anchoring. Because each term-boundary block hash is embedded in the Bitcoin transaction that carries the bid, ThankBitcoin's key history is anchored into Bitcoin. This anchoring is enforced as a consensus rule: a term's first block is only valid if it correctly commits to the Bitcoin block that decided the term, checked against a fixed, closed interval - so both auctioned and fallback terms can be re-verified by anyone, at any time, and cannot be poisoned after the fact by a late bid.


It is not a "slow chain"

Out of 1000 blocks in a term, 999 are ordinary blocks produced at the normal 60-second target. Only the one term-first block waits - it must wait for the decisive Bitcoin block to reach 8 confirmations (~80 minutes, roughly once every ~16.7 hours). That pause is a design feature: it aligns the two chains and gives bidders real time to get on-chain.


Parameters

• Base: Bitcoin Core v31.1 fork
• Block target: 60 seconds
• Term length: 1000 blocks
• Beneficiary share = miner share x 1.7 (integer math); fees go only to the miner. (The beneficiary share is deliberately the larger of the two - an intentional choice to draw attention to on-chain bidding in the early phase; miners keep 100% of fees as an offset. This tradeoff is discussed openly in the whitepaper, section R9.)
• Bitcoin confirmations required to settle the competition: 8
• PoW: SHA256d (same as Bitcoin). "Difficulty = Litecoin x 2/5" refers only to the powLimit numeric value, not the hashing algorithm - it is NOT scrypt.
• Addresses/keys: byte-for-byte identical to Bitcoin mainnet (bech32 "bc1q...", same WIF/xpub, BIP44 coin type 0). Chains are separated by network magic + ports.

Running a node / verifying the competition

Verifying term rollover requires reading the Bitcoin chain. Two options:

• (Recommended, highest assurance) Run your own Bitcoin full node and point the ThankBitcoin node at its local RPC - zero third-party trust, fully self-verified.
• (Zero-setup) Point it at any Bitcoin data service you trust (e.g. getblock.io, mempool.space, or any public node) - no full node required; the tradeoff is trusting that source's view of the Bitcoin chain.

The data source is pluggable; the consensus logic is identical either way.


Status

Mining goes live: 2026-07-15 01:00 UTC. At that moment the genesis block becomes valid and anyone can start mining. The genesis timestamp is fixed to this time; the anchor Bitcoin height and seed node(s) are published in the source repo and announced in this thread at launch.

What is public right now: the full source code, the complete mechanism, and a running demo chain (visible in the block explorer) for review and experimentation.



How to participate

Two ways to take part:

• Mine - run a node and produce blocks (SHA256d, same as Bitcoin). The only setup choice is how your node reads the Bitcoin chain: your own full node (zero trust), or a public data service (mempool.space built-in, or getblock.io via a tiny local proxy). The miner share + all fees go to you.
• Bid - publish a structured transaction on the Bitcoin chain to compete for a term's beneficiary slot. You build and sign it with your own wallet - keys and coins never leave you; no ThankBitcoin server is involved. Note a bid spends real Bitcoin and is not refundable (see the guide).

Step-by-step commands for both (mining examples + exact bid transaction format): https://thankbitcoin.com/how-to


Links

• Source code: https://github.com/thankbitcoin/thankbitcoin
• Block explorer: https://thankbitcoin.com/
• Whitepaper: https://thankbitcoin.com/whitepaper
• How to participate (mining & bidding): https://thankbitcoin.com/how-to

Known limits (stated honestly)

• Ordinary blocks are protected only by ThankBitcoin's own PoW; against double-spends of ordinary transactions ThankBitcoin is no safer than any small PoW chain.
• Fallback (no-bid) terms carry no Bitcoin-backed finality - they are self-verifiable but not anchored by hashrate. This is most common early on.
• Bitcoin gives finality of the competition result, not censorship-resistance of the competition process - the miner who packs the decisive Bitcoin block still has influence over which bids it contains.

Disclaimer

ThankBitcoin is an experimental, educational protocol research project. It is not an investment, not a security, not a financial product, and makes no claims of value, price, return, or future worth of any kind. Do not treat TBC as money or as an asset. The code is provided as-is for study and experimentation. Run it only if you understand what it does.

[thankbitcoin]

LAUNCHED - mainnet is live

ThankBitcoin mainnet went live as scheduled: 2026-07-15 01:00 UTC. The genesis block is now valid and anyone can mine. As promised in the opening post, the launch parameters are published below and in the source repo.


Launch parameters

• Genesis timestamp (nTime): 1784077200 (2026-07-15 01:00:00 UTC) - fixed, as announced.
• Genesis block hash: 00000012ff37debd9900c5dc93bd243e41fe770a0e285f9cd93943dca23122c6
• Anchor Bitcoin height (ANCHOR_BTC_HEIGHT): 958065
• P2P port: 9333

Seed node(s) - add to your bitcoin.conf-style config or pass on the command line:

Code:

addnode=seed1.thankbitcoin.com:9333
addnode=seed2.thankbitcoin.com:9333

or:

Code:

thankbitcoind -addnode=seed1.thankbitcoin.com:9333 -addnode=seed2.thankbitcoin.com:9333

Wallets

• Desktop (Windows .exe): coming shortly - will be posted in a follow-up reply
• Android (.apk): coming shortly - will be posted in a follow-up reply
• Wallet source: https://github.com/thankbitcoin/thankbitcoin-wallet

Verify for yourself

• Source: https://github.com/thankbitcoin/thankbitcoin (build it, hash your genesis, confirm it matches above)
• Explorer: https://thankbitcoin.com/
• How to mine / how to bid: https://thankbitcoin.com/how-to

Verifying term rollover reads the Bitcoin chain - run your own Bitcoin full node (highest assurance) or point the node at any Bitcoin data service you trust. The consensus logic is identical either way.


ThankBitcoin is an experimental, educational protocol research project. It is not an investment, not a security, not a financial product, and makes no claims of value, price, return, or future worth. Run it only if you understand what it does.

[weesdr]

Hi. Getting error when trying to build

root/thankbitcoin/src/ipc/test/ipc_test.cpp:27:47: error: static assertion failed
   27 | static_assert(ipc::capnp::messages::MAX_MONEY == MAX_MONEY);

[thankbitcoin]

Thanks for trying it out!

That assertion is from the multiprocess/IPC component (Cap'n Proto), which is enabled by default. ThankBitcoin changes MAX_MONEY relative to Bitcoin Core, and the value hard-coded in the IPC capnp schema (ipc_test.capnp) wasn't updated to match, so the static_assert in ipc_test.cpp fails. IPC is not needed to run a node or wallet.

Just build with IPC disabled:

    cmake -B build -DENABLE_IPC=OFF
    cmake --build build -j"$(nproc)"

With -DENABLE_IPC=OFF the entire ipc_test target is skipped, so the assertion never compiles. This is exactly how the release binaries are built, and everything (node, mining, wallet, RPC) works normally without IPC.
Windows wallet is up

The desktop wallet (Windows, 64-bit) is now available - a light wallet forked from Electrum, for standard send / receive on the ThankBitcoin mainnet.


Download page: https://thankbitcoin.com/download

Three builds are offered there: Standalone (recommended), Portable, and Setup/installer. Each download button is on the page, along with its SHA-256 and verification instructions.

SHA-256 checksums (verify before running):

Code:

Standalone:  18b2ea5a5bdc9ba797ec6787a210962dda2d77247fe51ae429226c4e26a4d688
Portable:    dd9e18aef27d7886005700c50777bd3ab8b86979131410f3a6d79ad536868b6d
Setup:       4ae7783ef2f529d56d0cd99611c44d2f4445212afc0e067c815a007c8fbfc96c

Verify with:

• PowerShell: Get-FileHash .\<file>.exe -Algorithm SHA256
• Linux / macOS: sha256sum <file>.exe

Note: these binaries are not code-signed yet, so Windows SmartScreen may show an "unknown publisher" warning and some antivirus may flag the PyInstaller bootloader. This is expected for community builds - verifying the SHA-256 is what proves the file is authentic. You can also build from source and compare.

Wallet source: https://github.com/thankbitcoin/thankbitcoin-wallet

Android (.apk) build is still in progress and will follow.

ThankBitcoin is an experimental, educational protocol research project. It is not an investment, not a security, not a financial product, and makes no claims of value, price, return, or future worth.

Android wallet is up

The Android APK is now available (arm64-v8a, for 64-bit phones - most devices from 2018 onward).


Download page: https://thankbitcoin.com/download

SHA-256 (verify before installing):

Code:

Android arm64:  d1674f28beeb6bad95a25d82eb5997dae0708ad815f0b051c550286d3c39e253

Verify: sha256sum ThankBitcoin-Wallet-1.0.0-arm64.apk - the output must match.

Note: the APK is unsigned, so Android will ask you to allow "install from unknown sources". This is expected for community builds; verifying the SHA-256 is what proves the file is authentic. You can also build it from source.

Wallet source: https://github.com/thankbitcoin/thankbitcoin-wallet

ThankBitcoin is an experimental, educational protocol research project. It is not an investment, not a security, not a financial product, and makes no claims of value, price, return, or future worth.