> ## Documentation Index > Fetch the complete documentation index at: https://dev.jup.ag/docs/llms.txt > Use this file to discover all available pages before exploring further. # Core Architecture > Jupiter Lend architecture: how Liquidity, Lending (Earn), and Vaults (Borrow) interact. Jupiter Lend is built on three core programs: **Liquidity** (the shared lending engine), **Lending** (Earn), and **Vaults** (Borrow). Lending and Vaults do not hold tokens directly. They CPI into Liquidity, which holds all underlying assets and tracks supply and borrow positions. ## Three-program design | Program | Purpose | Program ID | | --------- | --------------------------------------------------------------------- | --------------------------------------------- | | Liquidity | Core layer: token vaults, exchange prices, utilisation, rates | `jupeiUmn818Jg1ekPURTpr4mFo29p46vygyykFJ3wZC` | | Lending | Earn: deposit assets, mint jlTokens, supply into Liquidity | `jup3YeL8QhtSx1e253b2FDvsMNC87fDrgQZivbrndc9` | | Vaults | Borrow: collateralize, borrow, liquidate, supply/borrow via Liquidity | `jupr81YtYssSyPt8jbnGuiWon5f6x9TcDEFxYe3Bdzi` | Core architecture: Users → Lending (Earn) and Vaults (Borrow) → CPI → Operate → Liquidity Layer (Core) *** ## Liquidity (core layer) Liquidity serves as the foundational layer, owning all token vaults and custodying every deposited and borrowed asset. User-facing protocols never interact with tokens directly; they always make CPI calls into Liquidity to handle supply and borrow operations. ### Key state | Account | Purpose | | ------------------ | ------------------------------------------------------------------ | | TokenReserve | Per-mint: vault, exchange prices, totals, utilisation, rate config | | UserSupplyPosition | Per (mint, protocol): supply amount, withdrawal limit, status | | UserBorrowPosition | Per (mint, protocol): borrow amount, debt ceiling, status | | RateModel | Interest rate curve driven by utilisation | ### Protocol registration Protocols (Lending, Vaults) must be registered via `init_new_protocol(supply_mint, borrow_mint, protocol)`: * **Lending:** supply mint only (Earn supplies into Liquidity, no borrow) * **Vaults:** supply mint (collateral) and borrow mint (debt) ### Operate flow 1. **pre\_operate(mint):** marks the interacting protocol and timestamp on `TokenReserve` 2. Caller moves tokens into the Liquidity vault (via SPL transfer) 3. **operate(supply\_amount, borrow\_amount, withdraw\_to, borrow\_to, transfer\_type):** updates exchange prices, UserSupplyPosition/UserBorrowPosition, TokenReserve totals, and performs transfers Exchange prices and rates are updated during `operate`, so interest accrues on every interaction. *** ## Lending (Earn) Earn lets users deposit assets and receive jlTokens (shares). Deposits are supplied into Liquidity, and jlTokens represent a share of the pool with accrued interest and rewards. ### Key state | Account | Purpose | | ------------ | ----------------------------------------------------------------------------------------------------------------- | | LendingAdmin | Factory: authority, `liquidity_program`, rebalancer, auths | | Lending | Per-mint pool: mint, `jl_token_mint`, `token_reserves_liquidity`, `supply_position_on_liquidity`, exchange prices | ### User flow * **Deposit:** User transfers tokens → Lending CPIs Liquidity `pre_operate` + `operate(supply)` → mints jlTokens * **Withdraw/Redeem:** Burns jlTokens → CPIs Liquidity `operate(withdraw)` → user receives underlying The protocol signer for Liquidity CPI is the **Lending PDA** (not the user). Each Lending pool has a single `UserSupplyPosition` on Liquidity for that mint. The rewards rate model (separate program) adjusts the jlToken exchange price to include rewards on top of base yield. ### CPI summary | Caller | Signer | Supply position | Borrow position | | ------- | ----------- | ------------------------ | --------------- | | Lending | Lending PDA | Lending PDA (1 per mint) | None | *** ## Vaults (Borrow) Borrow vaults are collateralized lending markets. Each vault has a **supply token** (collateral) and a **borrow token** (debt). Users deposit collateral, borrow against it, and can be liquidated if collateral falls below the liquidation threshold. Positions are represented as NFTs. ### Key state | Account | Purpose | | ----------- | ---------------------------------------------------------------------------------------------------- | | VaultConfig | Params: supply\_token, borrow\_token, oracle, collateral\_factor, liquidation\_threshold, rebalancer | | VaultState | Runtime: total\_supply, total\_borrow, topmost\_tick, absorbed debt/collateral | | Position | User position: vault\_id, tick, supply\_amount, debt, liquidation status | | Branch | Liquidation structure: minima tick, debt factor, status | | Tick | Price-ratio ticks for collateralization | ### Tick-based pricing Vaults use **tick-based** pricing: collateralization is computed from a price-ratio tick rather than a simple LTV. Collateral factor is derived from tick ratio. Branches track liquidation state and merge positions when liquidated. ### User flow * **init\_position:** create Position + position mint NFT * **operate:** deposit/withdraw collateral, borrow/repay debt * **liquidate:** liquidate undercollateralized positions * **rebalance:** rebalancer supplies/borrows on Liquidity to match vault demand The protocol signer for Liquidity CPI is the **VaultConfig PDA**. Each vault has both a `UserSupplyPosition` (collateral) and a `UserBorrowPosition` (debt) on Liquidity. The Oracle program provides prices for collateral valuation and liquidation checks. ### CPI summary | Caller | Signer | Supply position | Borrow position | | ------ | --------------- | --------------- | --------------- | | Vaults | VaultConfig PDA | VaultConfig PDA | VaultConfig PDA | *** ## Shared data flow Both Lending and Vaults share the same Liquidity layer: | Shared account | Used by | Role | | ------------------ | ------- | --------------------------------- | | TokenReserve | Both | Aggregated supply/borrow per mint | | UserSupplyPosition | Both | Per-protocol supply | | UserBorrowPosition | Vaults | Per-protocol borrow | | Vault (ATA) | Both | Liquidity holds all tokens | | RateModel | Both | Interest rate parameters | ### Deposit (Earn) ``` User → Lending.deposit() → transfer tokens to Liquidity vault → pre_operate (Lending PDA) → operate(supply, borrow=0) → mint jlTokens ``` ### Borrow (Vaults) ``` User → Vaults.operate() → transfer collateral to vault → pre_operate (VaultConfig PDA) → operate(supply=collateral, borrow=debt) → update Position / Branch / Tick ``` *** ## Dependency graph | Program | Depends on | | --------- | ------------------------------------------- | | Lending | Liquidity (CPI), Lending Rewards Rate Model | | Vaults | Liquidity (CPI), Oracle | | Liquidity | Standalone | | Oracle | Standalone | *** ## Related docs * [Unifying Liquidity](/lend/liquidity/index): Liquidity layer overview and key features * [Earn Overview](/lend/earn/index): deposit/withdraw mechanics * [Borrow Overview](/lend/borrow/index): vaults, positions, liquidations * [Liquidity analytics](/lend/liquidity/analytics): market data, utilisation, exchange prices * [Oracles](/lend/oracles): price feeds for vaults * [Program addresses](/lend/program-addresses): program IDs and IDL