Cloudy is a decentralized storage platform that settles on Arbitrum with zk proofs verified on-chain. Anyone can upload files, or become a provider and earn USDG for hosting. All secured by client-side encryption, erasure-coded redundancy across providers, on-chain challenges, and incentives that reward reliable providers and compensate data owners.
Storage proofs, payments and penalties all settle on Arbitrum, so apps can rely on off-chain data the way they rely on on-chain state. Any contract can check a file’s storage status in its own transaction, and users pay in USDG on the chain they already use, with no bridge, no second chain and no extra token.
Each check is answered by one compact zk proof (an SP1 STARK wrapped in Groth16), made in about a minute on a single GPU and verified on-chain at a small fixed cost, however large the data. Frequent checks stay cheap, which keeps storage affordable and lets anyone with a GPU become a provider.
Others: Merkle-proof systems such as Filecoin PDP pay on-chain gas for every sampled piece, and zk designs built on Poseidon2 hashing, such as Codex, make the data owner hash for days (about 76 h for 1 TB, versus under 2 h with Cloudy’s keccak).
A provider that fails to keep or serve the data loses USDG collateral to the data owner, enforced by the contract. Owners are assured of compensation, and providers have real money at stake to keep data safe.
Providers that deliver fastest earn more, and a provider that withholds data can be forced to publish it on-chain. Owners get their data back quickly whenever they need it, for free, and no provider can hold it hostage.
Others: Only about 13% of Filecoin retrievals succeeded in a 2024 measurement, and Storj, Sia and Shelby charge for every read.
Reed-Solomon erasure coding lets any one third of the providers rebuild the file, so data stays recoverable even if most providers disappear or lose it, for no more than 3× storage.
| Topic | Cloudy | Existing systems |
|---|---|---|
| Where proofs are verified | On Arbitrum, by SP1’s official audited verifier | None of 17 surveyed networks verifies or slashes on Arbitrum |
| Who receives the penalty | The data owner, in the same transaction | None of 12 systems checked pays the owner. Filecoin PDP: the provider only loses that period’s payment |
| Catching a provider that dropped 1% of the data | 14.9% per check; about 80% over 30 days (10 checks) | Filecoin PDP: 4.9% per day; 77.9% over 30 days (30 daily checks) |
| On-chain cost of a proof | One 356-byte proof, about 247k gas in the verifier, whatever the sample count or data size | Plain Merkle proofs (PDP-style): about 26k gas per sample |
| Hash the user’s machine must compute | keccak: a 1 TB file’s tree in the browser in about 16 min to 1.8 h | Poseidon2-based designs (e.g. Codex): about 76 h for the same tree |
| Trusted setup | SP1’s shared setup, 18 contributors including Offchain Labs | EthStorage ran its own ceremony with 287 participants |
| Reads | Free for the owner; fastest third paid double; withholding challengeable on-chain | Filecoin: ~13% retrieval success (2024); Walrus best-effort; Storj, Sia, Shelby charge per read |
The data owner encrypts a file on their own device, splits it into redundant shards and places a storage order on Arbitrum, priced in USDG.
Orders and provider offers meet in an on-chain order book. Each matching provider takes one shard, checks it against the order, and locks USDG collateral to accept the contract.
Arbitrum regularly challenges providers on random pieces of the data. Each answers with one zk proof (an SP1 STARK over a keccak Merkle tree, wrapped in Groth16), generated in about a minute and verified on-chain at a fixed cost, whatever the file size.
The owner downloads from several providers at once, for free.
A provider that won’t deliver can be challenged on-chain to publish the data. A provider that fails to prove or serve the data loses collateral to the data owner.
Providers that deliver data fast earn a larger share of each payment, which keeps downloads fast and makes withholding data unprofitable.
Thanks to Reed-Solomon erasure coding, any one third of the providers can rebuild the whole file, so data survives even if two thirds of them lose their data.
Individuals, businesses, apps, RWA issuers and AI agents that need files stored with guarantees. They use the web app in a browser, or Cloudy Node.
Anyone with spare disk space and a GPU, who earns USDG for hosting. They use Cloudy Node.
Any contract on Arbitrum can read whether a file is stored validly and act on it. For example, a sample RWA token only mints while its documents are safely stored.
| Component | Role | Who uses it |
|---|---|---|
| Cloudy contracts | Run the order book, payments, proof checks, incentives and penalties on Arbitrum, and publish storage status | Cloudy Node, the web app and other smart contracts |
| Cloudy Node | Rents and hosts storage, and generates the zk proofs for providers | Data owners, providers |
| Web app | Rents storage straight from the browser, with nothing to install | Data owners |
| Relay network | Helps browsers and nodes reach providers behind routers, and forwards encrypted traffic only when a direct connection fails | Cloudy Node and the web app, in the background |
| Sample RWA contract | Mints tokens only while their documents are stored validly | RWA issuers (example) |
One app for both roles: rent storage with faster uploads and downloads, or rent out your spare disk and earn USDG. Desktop app and command line, for Windows and Ubuntu.
Just want to store files? The web app rents storage right in your browser.
Open web app