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Writz is a lending protocol on Stellar backed by native BTC. A Bitcoin Script holds the collateral on Bitcoin itself rather than a company, and it never becomes a wrapped token. Borrow USDC against it, repay on your own schedule, and recover your Bitcoin even if Writz disappears. Live on Stellar testnet.
Writz is on testnet only. The contracts are not audited yet. Never send real BTC, real USDC or a wallet that holds real funds to the testnet app.

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Start here

What is Writz?

The short version, and why it was not possible before.

How Writz works

A loan from deposit to release, in plain language.

Try the testnet app

What you need and the order to set it up, with free test coins.

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Use the app

Borrow USDC against BTC

Lock test BTC on signet and draw test USDC on Stellar.

Repay and release your BTC

Pay back the loan and take your collateral back.

Lend USDC

Supply USDC to the pool and earn the interest borrowers pay.

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Build on Writz

Integration guide

Prove a Bitcoin transaction from your Soroban contract or your app.

Bitcoin SPV SDK

The verify_transaction reference: signature, errors and the proof route.

Contract reference

The public functions of the Writz contracts.

For AI agents

Contract IDs, signatures and verified examples in a compact format.

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Understand the design

Technical architecture

How the Bitcoin script, the light client and the lending contract fit together.

Security model

What the protocol protects against, and what it assumes.

SPV vs wrapped Bitcoin

Where a light client differs from bridges, and where it shares their risks.

Research

The studies behind the design: SPV, oracles, rates and liquidation.