Developer overview
Build on Spield — an overview of the contracts, tokens, and integration paths for reading state and composing fixed-income products on Stellar.
Spield is built on Stellar's Soroban smart contracts, and its tokens and contracts are open and composable. This section is for developers integrating Spield into an app, indexing its data, or building products on top of PT and YT.
What this section covers — and doesn't
These docs describe Spield's public interface: the contract entry points you call, the tokens you interact with, the state you can read, and the events you can index. They do not cover internal implementation details — you don't need them to integrate.
Where to start
Architecture
The high-level layout: yield source, tokenization engine, vault, and market.
Contracts
The public function surface of each contract — reads and writes.
Tokens
PT, YT, and USDC as Stellar assets / SACs, and how to handle their units.
Reading state
Query positions, prices, solvency, and balances — free, no signing.
Integrating
Build, simulate, sign, and submit transactions from your app.
Events
The on-chain events Spield emits, for dashboards and indexers.
Contract addresses
Live testnet (and upcoming mainnet) contract + token addresses.
Tech stack at a glance
| Layer | Technology |
|---|---|
| Smart contracts | Soroban (Rust), on Stellar |
| Tokens | Stellar assets, wrapped as Stellar Asset Contracts (SACs) |
| Yield source | Blend lending market (via a thin adapter) |
| Reads | Soroban RPC simulateTransaction (free, no signing) |
| Writes | Build → simulate → sign (wallet) → submit → poll |
| Reference client | @stellar/stellar-sdk (JS/TS) |
The shape of an integration
Most integrations follow the same pattern:
- Reads are free simulations — query positions, prices, and solvency with no wallet and no fees.
- Writes are standard Soroban transactions, signed by the user's wallet.
- Events let you reconstruct full protocol state for dashboards or analytics.
Conventions used in these docs
- Base units. All token amounts on-chain are integers in base units (USDC, PT, and YT use 7 decimals).
10000000base units =1.0USDC. See Tokens. - Fixed-point rates. Rates and prices use a 12-decimal fixed-point representation.
implied_apyof0.08means 8%. - Function names are shown exactly as they appear on-chain (snake_case), e.g.
claim_yield.
Contract addresses
The live testnet (and upcoming mainnet) contract and token addresses are on the Contract addresses page. This documentation focuses on the interface and integration patterns; wire your app to those addresses via your own configuration.
Bridge USDC to Stellar
Step-by-step — bring USDC to Stellar from Ethereum, BSC, Polygon, Arbitrum, Solana, or Tron using Spield's built-in bridge.
Architecture
A high-level map of Spield's on-chain architecture — the yield adapter, the tokenization engine, the Fixed-Rate Vault, and the time-decay market.