How to read these docs
What each section is for, which page answers which question, how the numbers get here, and what the conventions mean.
Spec v0.9.1, reviewed 2026-09-08
These pages are organised by what you are trying to find out, not by how the contracts are laid out. Each page answers one question and says which rule of the specification settles it.
The five sections
| Section | Written for | Answers |
|---|---|---|
| User guide | Anyone about to deposit, borrow, lend or provide liquidity | What happens when I press this, what does it cost, what can I lose |
| Protocol | Anyone who wants the mechanism rather than the effect | How the price is computed, how a liquidation runs, where the interest goes |
| Risks | Everyone, before the first transaction | What can cost me money, what the contracts do about it, what is left over |
| Developers | Integrators, indexers, interface operators | Call order, events, invariants, what an interface must display |
| Legal | Everyone | The sixteen statements you accept before your first transaction, and what the collateral legally is |
If you read one page from each of the first three, read Borrow, Price regimes and Risks. If what you want to know is what is actually in the contracts on the day they land, that is How it starts, and the answer is nothing.
Where the numbers come from
Every protocol constant on these pages is printed from packages/protocol/src/params.ts, which is generated from section 13 of the specification. A page never types a parameter by hand. Hovering a number tells you what it is and which rule it comes from, and a reference to a constant that does not exist fails the build rather than reaching a reader.
Three kinds of number appear, and they are not the same kind of claim:
- Constants. Written into the contracts at deployment. They cannot change afterwards. Most numbers here are these.
- Formulas. Computed on-chain from constants and from what the market is doing: the borrowing limit of the day, the debt ceiling of a branch, the liquidation bonus, the confidence in the price.
- Measurements. What actually happened, over a stated window, on stated data. The three years of borrowing limits on page Volatility and the borrowing limit are of this kind. They describe the past and forecast nothing.
Where a constant is still provisional — waiting on a measurement that has to finish before deployment — the page says so and names the measurement. The list of those is What is measured before launch.
The three blocks
Three kinds of paragraph are set apart from the prose.
Guarantee
A property that is true by construction: something the contracts cannot do otherwise. It is never softened and never carries a condition that is not stated inside it.
Risk
A way you can lose money. Also never softened. Where the protocol has no mitigation, the block says there is none rather than describing something adjacent.
How it is calculated
A calculation, shown rather than asserted, so you can reproduce it.
Conventions
- Collateral ratio is the dollar value of your deposit divided by your debt. A ratio of 125% means you owe 80 cents for every dollar deposited. Loan-to-value is its inverse, and both appear because the contracts use the first and screens use the second.
- Tier 1, tier 2, tier 3 are the three risk classes of collateral. Tier 1 is index funds, broad-market funds and gold. Tier 2 is the six mega caps, the silver fund and five other large caps. Tier 3 is the four most volatile single names. The full lists are on Branches and tiers.
- LIVE24, DEGRADED, FROZEN, HALT are the four states of a branch's price, and they are the only regime names used anywhere. They describe how well the protocol can see the price, and each one has an exact table of what is open. See Price regimes.
- Rule references look like
R-6.1.3. They point at the numbered rules of the functional specification, which is the single source these pages are written from. A rule keeps its number for the life of the protocol. - A branch is one contract per collateral: its own positions, its own debt, its own Stability Pool, its own price sources. Nothing is pooled across branches.
- Day 0 is the deployment transaction. Every dated step in the protocol counts from it, or from the day a branch activated.
What these pages will not do
They will not recommend a rate, a tier, an amount or a strategy. They will not compare Fyber with a competitor. They will not tell you a yield to expect: where a range appears, it is what has been paid over a stated period, with the reason it moved.
The version of the specification these pages track is printed at the top of every one of them, with the date they were last read against it.