Custody

Key points

• Custody is the safekeeping of assets, whether by a third party on someone's behalf or by the owner of the funds themselves.
• In crypto, custody comes down to who controls the private keys, since whoever controls the keys controls the funds.
• Choosing between third-party custody and self-custody involves a trade-off between convenience and direct control.

What is custody?

Custody, in finance, is the safekeeping of assets. It can mean a third party holding assets on behalf of a client, like a bank, or a person holding and controlling what they own themselves. In the crypto world, the concept takes on a specific shape: since access to funds depends on cryptographic keys, custody essentially comes down to who controls those keys.

How it works

In crypto, funds are recorded on the blockchain, and the power to move them belongs to whoever holds the corresponding private key. That's why talking about custody means talking about control of keys. If a third party holds the keys on behalf of the user, this is called third-party custody; if users hold and control the keys themselves, this is called self-custody. This distinction is the foundation of the entire discussion around custody in the industry.

In third-party custody, a service, such as an exchange, holds the keys and moves the funds on the user's behalf. This brings convenience: users don't need to worry about storing keys or fear losing them, and there is someone to turn to if something goes wrong. The trade-off is dependence: the user trusts that the third party is honest, competent, and solvent, since, in practice, the third party is the one holding direct control of the funds.

In self-custody, users hold their own keys and control the funds directly, without an intermediary. This maximizes autonomy and eliminates dependence on third parties, but shifts all responsibility to the user: losing the keys means losing access, with no one to turn to. The choice between the two models, or combinations of them, depends on the balance each person seeks between convenience, control, and responsibility.

Understanding custody helps clarify one of the most important decisions when dealing with crypto.

Why it matters

Understanding custody helps clarify who actually controls the funds in each situation and enables a conscious decision between relying on a third party or taking direct control. It's a central distinction in crypto. This is a concept about security and control, and does not represent any operating recommendation.

Risks and limitations

In third-party custody, users depend on the honesty, competence, and solvency of whoever holds the keys; failures or fraud by the custodian directly affect the funds. In self-custody, all responsibility falls on the user, and losing the keys means irreversible loss. Each model trades one risk for another. Nothing here represents an operating recommendation.