XChain is an open-source, tiered meta-blockchain — a 2-Domain → 3-Layer → 5-Tier architecture — that turns verifiability into shared, public infrastructure, so almost anything the world records can be proven, not just trusted. Whitepaper · Testnet MVC edition · 2026 · Apache-2.0 · Live network: www.xscan.org A note on method: this whitepaper describes an architecture and a running system. Where a component is fully live, We say so; where it is in progress or still a stand-in, We say that too — the honest, consolidated status of every part lives in §10, Roadmap & Status, and the live operational numbers on Network Status. ("We" is capitalized throughout on purpose: it means all of us — builders, users, and anyone who believes in open infrastructure that belongs to everyone, the founding team included.) Community-owned: XChain is built, run, controlled and optimized by its community as a public good, with the common good of the community and of society first. Nothing here — its direction, strategy, technology, or this document — is fixed by a founding team; all of it is open to contribution and, over time, to community governance (§12).

Abstract

Blockchains still cannot hold the world's data. The fastest single chains process a few thousand real transactions per second, and the cost of consensus makes recording high-volume, low-value data — likes, views, sensor readings, logs — economically impossible on chain. Scaling horizontally into many chains trades this for another wall: lost composability and fragile, expensive cross-chain state.

XChain resolves the tension by refusing to make one chain do everything. It is a tiered meta-blockchain, organized on three independent axes — 2 Domains → 3 Layers → 5 Tiers:

2 Domains are the invariant boundary — value vs data — enforced by the UAC primitive, so value-bearing data can never live in the data Domain.
3 Layers are the functional split — Settlement · Execution · Data.
5 Tiers (T0–T4) are the fine grain, each with cryptographic assurance and storage matched to the value of the data (T0 = Settlement; T1, T2 = Execution; T3, T4 = Data).

The Domains are joined by a single principle — verify, don't re-execute — and connected by a narrow waist of seven core primitives, hard-specified so many teams build in parallel and the community builds on top without permission.

This design makes verifiability a public good: the marginal cost of recording a low-value event approaches zero, while value and atomicity concentrate in a small, maximally-secured core. XChain invents no new primitive — it integrates proven components (Cosmos, Celestia, IBC, pessimistic proofs, recursive ZK) at a new architecture.

And it is a public good in the fullest sense: built, operated and optimized by its community, with the common good of that community and of society as the first priority. It belongs to no company and to no founding team — everything, this whitepaper included, is open to contribution and, over time, to community governance (§12).

XChain runs today on a live public testnet (the Testnet MVC). Six of the seven primitives are real on-chain modules; the seventh, proof aggregation, is real in its aggregation logic while its cryptographic prover remains a MOCK/stand-in — an honest, open piece of work. Headline capacity figures describe aggregate nominal throughput, not a single global composable state. The precise, current status of every claim is consolidated in §10; the live network numbers are on Network Status.

Thesis in one line: separate the world's data by value, verify instead of re-execute, and a blockchain can become a verifiable record layer for almost everything — as a public good anyone can build on.