Buy Cartesi

Cartesi is infrastructure for building blockchain applications in ordinary software, rather than in the narrow programming environment most smart contracts are written for. It lets a developer run a full Linux system inside a verifiable execution environment, with the result settled on Ethereum. CTSI is the network's token.

That is a developer tools proposition rather than a consumer one, and it is worth being clear about that up front. Buying CTSI is a bet on whether developers choose this approach to building applications. Our guide to blockchain layers explains where rollups sit, and our guide to Ethereum covers the network Cartesi settles to.

What problem is Cartesi trying to solve?

Smart contracts on Ethereum run in the Ethereum Virtual Machine, which is deliberately constrained. Computation is expensive, memory is limited, and developers write in Solidity using libraries built specifically for that environment. Anything computationally heavy, such as a physics engine, a machine learning model or a complex simulation, is impractical to run there.

Cartesi's answer is the Cartesi Machine: a deterministic virtual machine based on the open RISC-V instruction set, capable of booting Linux. Because it runs a real operating system, developers can use mainstream languages and libraries rather than rewriting everything for the blockchain.

The computation happens off chain, where it is cheap. What goes on chain is the claim about the result, plus a mechanism for anyone to challenge that claim if it is wrong.

How Cartesi Rollups work

Rather than putting every application on one shared chain, Cartesi gives each application its own rollup with its own dedicated compute.

Inputs are submitted to contracts on Ethereum, so the ordering of transactions inherits Ethereum's censorship resistance. A node runs those inputs through the Cartesi Machine and produces the new state, along with any outputs such as token withdrawals. Those outputs are validated on chain before they can be executed.

Cartesi Rollups are modular in how they are deployed. An application can run as a layer two settling directly to Ethereum, as a layer three on top of another rollup, or as a sovereign rollup, and it can use different data availability arrangements. That flexibility is a feature for builders, but it also means "an application built on Cartesi" does not describe a single, uniform set of security properties. Each deployment has to be assessed on its own configuration.

Fraud proofs and what Stage 2 means

An optimistic rollup assumes the results submitted on chain are correct unless someone proves otherwise. That only works if the proving mechanism actually functions and anyone is allowed to use it. Many rollups in the market still rely on a permissioned set of proposers or a security council that can override outcomes.

Cartesi's dispute system is called Permissionless Refereed Tournaments, and a second generation algorithm known as Dave has been developed to improve on it, particularly against attackers who try to win by causing delays. Participants post a bond to raise a dispute, which is what makes spamming challenges expensive.

The project tested this in public with the Honeypot: an application on mainnet holding a bounty that anyone is invited to steal by breaking the system. The independent research site L2BEAT, which classifies rollups by how much trust they require, has recognized the Honeypot as a Stage 2 deployment, its highest maturity classification and one held by very few projects.

The honest reading of that includes the failure. A stress test in late 2025 exposed a liveness bug in the dispute implementation, which was fixed before the system returned. Finding a bug in a live bounty environment is the intended outcome of a honeypot, and it is also a reminder that this technology is new.

What is CTSI actually used for?

Staking. CTSI is staked in a proof of stake contract on Ethereum. Stakers can run a node or delegate to a staking pool, and rewards are distributed by block production, weighted by share of total stake. Our guide to crypto staking explains the general model. Governance. Staked CTSI carries voting rights on proposals, including grant funding for ecosystem work. Voting is run through Snapshot, so it signals holder preference rather than executing changes automatically. Security bonds and bounties. CTSI is used for bonds in the dispute system and for bounties such as the Honeypot. Validator incentives. A validator marketplace, in which holders delegate to validators serving specific applications, has long been part of the design and is not fully in place.

There is one thing CTSI is not, and it is the most common misunderstanding about the asset. It is not the gas token that users of Cartesi applications must pay. Applications settle to Ethereum and pay Ethereum fees, and a developer building on Cartesi is not required to use CTSI in their product. That gap between network usage and token demand is central to assessing CTSI.

Supply, the reserve, and where rewards come from

CTSI's supply was fixed at one billion tokens when the project launched, with a large portion set aside in a reserve to fund staking rewards over time.

This means staking rewards are paid out of a pre-allocated pool rather than created by ongoing inflation, and that pool is finite. Once it is exhausted, continuing to pay rewards at any level would require a decision to change the token's economics, which is a governance and foundation matter rather than something guaranteed by the protocol. Anyone holding CTSI for staking rewards should treat the current arrangement as a policy that can change, not a permanent feature.

Governance and who actually steers the project

Direction comes from a combination of the Cartesi Foundation, which holds treasury funds and publishes transparency reports on its spending, and community voting by stakers on proposals and grants.

This is a common structure and it has a common weakness. Snapshot voting is off chain and non binding in a technical sense, participation in token votes is usually concentrated among a small number of large holders, and the foundation retains significant practical influence through funding decisions. It is more accountable than a purely private company and considerably less so than the on chain governance of a large network.

Which network is your CTSI on?

CTSI is natively an ERC-20 token on Ethereum. Bridged representations also exist on other networks, including BNB Chain, and those are separate tokens tracking the same asset rather than the same token in two places.

Addresses are not interchangeable across networks. Sending CTSI to an address on a network the receiving wallet or exchange does not support is one of the most common ways people permanently lose tokens. Before any transfer, confirm which network the destination expects and make sure the network you are sending from matches. Our guide to sending crypto on the wrong network covers what can and cannot be recovered.

What are the risks of holding CTSI?

Adoption risk. The technology is capable, but the case for the token depends on applications being built and used at scale. Developer infrastructure projects can be technically excellent and still fail to attract builders. Weak link between usage and token value. Applications built with Cartesi are not required to use CTSI, so growth in usage does not automatically translate into demand for the token. Reward sustainability. Staking rewards come from a finite reserve. What happens when it runs down is a governance decision, not a protocol guarantee. Competition. Rollup frameworks, app specific chain toolkits and general purpose high performance networks all compete for the same developers, and several are far better funded and more widely used. Technical risk. Fraud proof systems, bridges and rollup contracts are complex and relatively new. A liveness bug has already been found in the dispute system in live conditions, and further bugs are possible. Governance concentration. Voting power follows stake, and foundation funding decisions carry substantial weight. Liquidity and volatility. CTSI is a small capitalization altcoin. It can move sharply, and market depth can be thin when conditions turn. No consumer protection. Crypto assets are high risk and your capital is at risk. CTSI is not insured by the Federal Deposit Insurance Corporation and it is not protected by the Securities Investor Protection Corporation. You should be prepared to lose all the money you put in.

Buying CTSI with US dollars on CoinJar

CoinJar has operated since 2013 and lists CTSI against US dollars, so you can buy, sell and hold it without converting through another cryptocurrency first. Current charges are on our fees page, and live US dollar rates are on our cryptocurrency prices page.

CoinJar, Inc. is registered with FinCEN as a money services business and holds money transmitter licenses in a growing number of states, NMLS ID 2492913. You can check whether CoinJar operates in your state before you sign up.

How is CTSI taxed in the US?

The IRS generally treats CTSI as property. A taxable event can occur when you sell it for US dollars, exchange it for another cryptocurrency, spend it or give it away.

The IRS explains these rules on its digital assets guidance page. Our guide to downloading your transaction history for tax shows how to get the records you need. This is general information, not tax advice. Consider speaking to a qualified tax professional about your circumstances.