XChain is an open-source, two-layer meta-blockchain 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 & Implementation 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.)

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 two-layer meta-blockchain. The Execution Layer is a set of consensus chains (Cosmos SDK + CometBFT + IBC) that hold value, assets and identity. The Data Availability Layer is a set of append-only, namespaced logs on a DA substrate (Celestia), with no per-log consensus, built for the ocean of high-volume low-value data. The two layers are joined by a single principle — verify, don't re-execute — and separated by one rule: security follows the asset, so value-bearing data can never live on the Data Layer. Connecting them is a narrow waist of seven core primitives, hard-specified so that many teams can build in parallel and the community can build 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.

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.

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.