Introduction

What is Aspens?

Aspens is an architecture for non-custodial crosschain trading: users keep custody of their assets until a trade settles, and every leg is verified on the chain it lives on. The first service built on the protocol is the Aspens Market Stack (AMS) — a deployable orderbook that matches and settles trades across chains.

Aspens Market Stack

A stack pairs an off-chain matching engine with on-chain trading contracts on every connected chain. Operators run their own stacks; developers build apps and traders submit orders against them via gRPC or the Aspens SDK.

What it gives you

Crosschain orderbook — a single book matches orders whose base and quote tokens live on different chains.
Non-custodial — funds stay under user control via per-chain trading contracts (MidribV3 on EVM, the Midrib Anchor program on Solana). Cancellations just release an off-chain reservation; withdrawals require a TEE-signed voucher.
Gas-free order entry — placing or cancelling an order is an off-chain, signed gRPC call (EIP-191 on EVM, Ed25519 on Solana) with no on-chain transaction. The arborter pays the gas for net on-chain settlement; users pay gas only for their own deposits and withdrawals.
Independent operation — operators run their own stack with their own infra, chains, tokens, markets, and fees.
Verifiable — every trade is reflected on both chains via netted on-chain settlement and recorded in the stack's trade journal.

Chain support

Architecture	Status	Curve	Trade contract
EVM	Production	secp256k1	`MidribV3`
Solana	Production	Ed25519	Midrib Anchor program
Hedera	In progress	secp256k1	(EVM-equivalent)

New architectures are added by implementing the chain-traits interface and registering a curve with the signer. The matching engine is chain-agnostic.

How it feels to trade

Orders match instantly and cost no gas to place or cancel — the responsiveness of a centralized exchange — while your funds stay in self-custody on their native chain and every trade settles on-chain. You pay gas only to move funds in or out.

Where to go next

Core Concepts — orderbook, optimistic ledger, settlement
Quick Start — make your first crosschain trade
Operator Guide — deploy and configure a stack
Developer Guide — build against an existing stack
API Reference — gRPC services and message shapes

Architecture overview

Architecture

A stack has these moving parts:

Arborter — orderbook + matching engine, chain dispatcher, gRPC server. Holds the per-chain instance signer keys inside a TEE.
Signer — TEE process that mints and uses the per-chain signing keys (secp256k1 or Ed25519). Wire-authenticated with HMAC + monotonic counter on every request.
Trading contracts — MidribV3 (EVM) and Midrib (Solana) hold deposited balances and apply net settlement (settleBatch) + voucher withdrawals.
Journal — TimescaleDB-backed record of orders, trades, and settlements.
Frontend — terminal-ui (trader-facing) and admin-console (operator-facing) Web UIs.