TSUNAGI
A block-producing Cardano node written in Zig
Independent implementation. Built without grants. Built without treasury funding. Built in public. Proven the only way that counts — with canonical blocks on the Cardano Preview chain, externally verifiable by anyone.
Verify independently:
curl "https://preview.koios.rest/api/v1/pool_blocks?_pool_bech32=pool1nu2…fw5ts"
— the chain is the source of truth, not this website.
A real node, not a fork
TSUNAGI is a from-scratch implementation of the Cardano block-producer role,
written in Zig. It evaluates VRF leadership for every slot, forges
and signs blocks (KES/opcert), publishes them atomically, and serves them to peers
over the standard node-to-node mini-protocols — ChainSync and BlockFetch — to an
unmodified cardano-node, which accepts them into the canonical chain.
It is not a fork of the Haskell node, not a wrapper, and not a simulation. Every canonical block listed on this site was forged by this code and adopted by the Cardano Preview network under normal consensus rules, competing against every other pool's blocks.
On mainnet, TSUNAGI currently runs as a read-only, parity-proven follower — it does not produce mainnet blocks. See /mainnet/.
Built without permission
A real implementation
Not a fork, not a wrapper — an independent implementation of the Cardano block-producer role.
Written in Zig
A single static binary. Low-level, auditable, no runtime to trust.
Zero grant funding
No Catalyst, no foundation grants, no VC. The work funded itself.
Zero treasury draw
Not a single ada of treasury money. Independence is the point.
Every failure becomes a test
Each closed incident is pinned by a regression test. A frontier cannot silently reopen.
Every incident recorded
Fourteen incidents documented — thirteen verified-closed, one recovered pending root cause — in the Kintsugi record.
Every block recorded
Every canonical block is listed and verifiable against the chain — including the orphans.
Truth-first by design
Nothing here is a marketing counter. If a value can't be fetched, the site says unavailable.
Five guardians, one node
TSUNAGI's architecture is organized around five named subsystems — observe, protect, recover, reconnect, learn. The full explanation, with diagrams, is on the Architecture page.
Observe
Self-observation: acceptance tracking, verdicts, external cross-checks against the chain.
Protect
Forge gates that refuse any block the node cannot prove valid to itself first.
Recover
Watchdogs, quarantine, rollback chains — failure never cascades.
Reconnect
Parked peers, contiguous push walks — the network path that wins the propagation race.
Learn
The failure-memory system: every incident becomes a regression test and a documented lesson.