IBC applications and middleware for Cosmos SDK blockchains

Early IBC work started in the ibc-go repo. As the repo grew, the need arose to parallelize the work among many teams.

The ibc-apps repo is meant to be an easily discoverable, navigable, central place for modules and middleware.

IBC-Apps is for:

• Core ibc-go contributors; it frees them from having to maintain IBC Apps,

• Publishers of ibc apps, so their apps can be easily found, and

• Everyone who uses IBC and wants to benefit from the full range of its capabilities.

The Inter-Blockchain Communication Protocol (IBC) is a protocol to handle the authentication and transport of data between two blockchains. IBC requires a minimal set of functions, specified in the Interchain Standards (ICS). These specifications do not limit the network topology or consensus algorithm, so IBC can be used with a wide range of blockchains or state machines. The IBC protocol provides a permissionless way for relaying data packets between blockchains, unlike most trusted bridging technologies. The security of IBC reduces to the security of the participating chains.

IBC solves a widespread problem: cross-chain communication. This problem exists on public blockchains when exchanges wish to perform swaps. The problem arises early in the case of application-specific blockchains, where every asset is likely to emerge from its own purpose-built chain. Cross-chain communication is also a challenge in the world of private blockchains, in cases where communication with a public chain or other private chains is desirable.

Cross-chain communication between application-specific blockchains in Cosmos creates the potential for high horizontal scalability with transaction finality. These design features provide convincing solutions to well-known problems that plague other platforms, such as transaction costs, network capacity, and transaction confirmation finality.

IBC apps can be split into two categories - modules and middleware.

IBC Modules are self-contained applications that enable packets to be sent to and received from other IBC-enabled chains. IBC application developers do not need to concern themselves with the low-level details of clients, connections, and proof verification.

IBC Middleware are self-contained modules that sit between core IBC and an underlying IBC application. This allows developers to customize lower-level packet handling. Multiple middleware modules can be chained together.

If you'd like to include software in this repo, please see contributing.

Modules and middleware developed by other awesome teams in the ecosystem:

| CosmWasm NFT Transfer (ICS 721) | WASM Contract | Public Awesome (Stargaze), Ark Protocol | An application that enables cross chain NFT transfer. CosmWasm implementation of the above, written in Rust. | | recovery | Middleware | Evmos | Middleware enabling the recovery of tokens sent to unsupported addresses. | | ibc-rate-limit | Middleware | Osmosis Labs | Middleware that limits the in or out flow of an asset in a certain time period to minimise the risks of cross chain token transfers. This is implemented as a middleware wrapping ICS20 with the rate limiting logic implemented by cosmwasm contracts. | | Interchain Atomic Swap | WASM Contract | Side Labs | An application that facilitates inter-blockchain peer-to-peer asset swaps. | | Interchain Liquidity | WASM Contract | Side Labs | An application that splits the state of a weighted liquidity pool between two chains, enabling inter-blockchain automated asset swaps. |