Bitcoin-backed loans. Finally done right.


Firefish for borrowers

Firefish is built different. Just like bitcoin itself.

As bitcoiners, we have found ourselves in situations where we needed money for investments or personal use. However, we never felt comfortable handing over our bitcoin collateral to a centralized lender. That is why we launched Firefish – a bitcoin-backed lending platform based on self-custody, decentralization, and ease of use.

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No custody

You retain control of your bitcoin by placing it in an on-chain multi-signature contract, rather than relinquishing your private keys.

Real cash

You receive the money in your bank account just like a regular loan. No stablecoins involved.

Decentralized lending

Loans are made on a bilateral basis between members of the platform, rather than through a central lender.


The Firefish protocol and most of its implementation code are open source.

Bitcoin native

The platform is powered by the bitcoin network, with no reliance on sidechains or smart contract platforms.

Bureaucracy free

If you have bitcoin, you have credit, with no need for additional income verification.

How it works

Lock your

Use our platform to securely lock your bitcoin on specific multi-signature address, which secures your loan until you pay it back.


Conveniently receive the loan funds in your bank account, similar to a traditional loan.

Repay and unlock
your Bitcoin

Once you repay the loan, your bitcoin will be automatically released from the escrow and returned to your personal wallet.

Our strengths

Do not sell your bitcoin. Use it to achieve your goals.

  • Buy a house or complete a renovation.
  • Take a nice vacation.
  • Buy more bitcoin.
  • Make a large purchase (e.g. car or mining equipment).
  • Seize an investment opportunity.

Tax benefits

Taking out a loan with Firefish won’t trigger any capital gains tax, unlike when you sell your bitcoin and may be subject to such taxes.

Fit for HODL

If you are interested in potentially benefiting from future price appreciation of bitcoin, a Firefish loan can allow you to maintain or even increase your bitcoin exposure.

Current interest rates

  • USD
    5% p.a.
  • EUR
    6% p.a.
  • CZK
    7% p.a.


Juraj Bednár“Bitcoiners need a way to make use of their investment without doing the worst thing - selling their Bitcoin. Firefish is a great Bitcoin-native way to use Bitcoin as a collateral without selling it, built by Bitcoiners.”

Juraj Bednár

enterpreneur, educator

Ondřej Raška“Firefish is an exceptional team. They have built a service that does it right compared to centralized solutions.”

Ondřej Raška

Founding partner at Miton

Kixunil“After thorough analysis I concluded that the design is very secure, paranoid even. All hard core Bitcoiners should really enjoy it!.”


Bitcoiner. Rust-bitcoin contributor

The difference

FirefishCustodial lendersDeFi
No custodyYesNoYes
Real time collateral transparencyYesNoYes
No collatelar rehypotecationYesNoNo
Real cashYesYesNo
Brinding/wrapping freeYesYesNo


loans essential knowledge.

  • To secure your loan, we require you to place your bitcoin in a designated multi-signature escrow address. This escrow can only be accessed in two ways: returned to your wallet (e.g. if you pay back the loan) or transferred to the liquidator's address (e.g. if you don't repay the loan by the due date).
  • After a certain date in the future (the loan maturity date plus a buffer period), you can retrieve your bitcoin from the escrow and send it back to your private wallet without any further interaction with anyone. Even if the Firefish platform no longer exists, you will still be able to access your bitcoin.
  • For the loan to be safe for both you and the investor, it's important that the value of the collateral always exceeds the value of the loan.
  • If the value of your bitcoin falls close to the value of the loan (for example, due to a drop in the bitcoin exchange rate), your bitcoin will be sold on the open market and the proceeds used to pay off the loan. This process is called liquidation.
  • You have the option to add more bitcoin to the collateral to avoid liquidation. You can also pay off the loan early at any time to avoid liquidation.