Question 1

I’m ready to build with IBC. How can I get started?

Accepted Answer

Welcome to IBC’s developer community! The easiest way to get started with the code is by diving into our Github repo or reviewing the Interchain developer tutorials to learn about core IBC concepts. Developers new to the Interchain stack can join the Interchain Developer Academy, a seven-week learning program that covers IBC implementation in chain and application environments. Project teams can apply to the Interchain Builders Program, an incubator and mentorship program for new projects. Both programs are free and sponsored by the Interchain Foundation.Make sure to join the developer section on the Interchain Discord to meet the community.

Question 2

What is the Cosmos IBC? Is it the same as the IBC Protocol?

Accepted Answer

Yes, the Inter-blockchain Communication Protocol is the Cosmos IBC. It used to be called “Cosmos IBC” because it started in the Cosmos ecosystem. Today, IBC is used not only in Cosmos, but also connects to blockchain ecosystems like Polkadot and Avalanche. Over 115 blockchains are IBC-enabled.

Question 3

Is there a cost to build with IBC?

Accepted Answer

No, there are no costs or fees to build with IBC. The IBC implementations, middleware, and applications are offered free of charge on our open-source Github repository.In addition, there is no in-protocol rent extraction with IBC. Chains, apps, and IBC-enabled contracts do not pay any fees to the protocol to process transactions. This means that anyone, anywhere can get started building with IBC code entirely free of charge.

Question 4

Does IBC depend on a specific blockchain or token?

Accepted Answer

IBC is a general-purpose blockchain interoperability protocol. It is designed to be integrated into blockchains to enable interoperability. The IBC Protocol does not have a blockchain, nor require any particular blockchain to operate. IBC does not use or rely on any specific token to operate.

Question 5

Is IBC limited to chains using the Cosmos SDK and CometBFT, or can chains in other ecosystems connect to IBC?

Accepted Answer

IBC can be enabled on any chain. It is enabled on almost all Cosmos SDK chains. It can be set up for parachains within the Polkadot ecosystem using the ibc pallet with the hyperspace relayer, and live IBC implementations exist for Ethereum and rollups.Many teams are working to extend IBC accessibility to other ecosystems, including Avalanche, Near, Solana, and others.

Question 6

Is IBC limited to communication between chains, or can smart contracts communicate over IBC?

Accepted Answer

No, IBC is not limited to communication between chains. The protocol also enables modules and smart contracts on different chains to communicate.Developers can directly connect two modules or two smart contracts, or a smart contract can call into an existing module, e.g. ICS-20, token transfer. For smart contracts to communicate directly, the contract must contain logic for channel creation and logic to send and receive packets.The most common type of smart contract used with IBC is CosmWasm. More information can be found here.

Question 7

What is CosmWasm?

Accepted Answer

CosmWasm is the smart contract platform for the Interchain Stack. It allows developers to write smart contracts in Rust, which are then compiled to Wasm bytecode. CosmWasm was designed with interoperability in mind, and its smart contracts can use IBC to communicate with contracts and modules on connected chains to, for example, carry out token transfers and interchain queries.

Question 8

Do I need permission to integrate IBC into my blockchain?

Accepted Answer

No, IBC is an open-source, permissionless blockchain interoperability protocol. You don’t need the permission of the Interchain Foundation, the development teams, or that of any third party to integrate IBC interoperability into a blockchain.

Question 9

Does the IBC Protocol charge fees for cross-chain transactions?

Accepted Answer

No. I contrast to many blockchain bridges, IBC cross-chain transactions do not impose additional costs. The only costs are the origin and destination chain gas fees, which are required to process the transaction.From a technical perspective, the user pays to send the transaction, and the relayers pay to receive, acknowledge, and timeout transactions.

Question 10

Can I customize IBC for my use case?

Accepted Answer

Yes. IBC can be customized with applications, which provide standard semantics for specific cross-chain interactions. IBC applications are also called “IBC modules”. Popular IBC applications include fungible token transfers, interchain accounts, and interchain data queries. Additionally, IBC middleware lets developers customize package handling to add new functionality not supported by the main application. It does this by interposing modifying logic between the core transport layer and the application. Examples include the transfer rate limit middleware, callbacks middleware, and token filter middleware. A single IBC application can have multiple middleware attached to it depending on the desired end-state functionality, and middleware is re-usable and composable for flexible development. This reduces redundancy and improves efficiency.

Question 11

What is a light client?

Accepted Answer

A light client is a lightweight representation of a blockchain that exists within another blockchain's state machine. Unlike full nodes, light clients don't process every transaction or store the entire blockchain. Instead, they verify block headers and cryptographic proofs to validate the state of their counterparty chain.Light clients enable secure cross-chain communication. They allow one blockchain to efficiently verify information from another while minimizing computational and storage requirements.

Question 12

What kinds of light clients does IBC support?

Accepted Answer

IBC supports a broad range of client types as long as a client complies with the client semantics in the ICS-02 client specification. This means IBC can be used with clients supporting consensus state proofs, state transition functions, zero knowledge proofs, single signer or multi signer attestations of state. A diverse range of security models can be used to underpin IBC connections.

Question 13

Which languages are supported for writing light clients?

Accepted Answer

Light clients are a lightweight representation of a destination blockchain. They allow blockchains to verify the state of counterparty chains without validating the entire chain. New light clients can be written in Go using the ibc-go protocol implementation, Rust using the ibc-rs implementation, and any language that compiles to WebAssembly using the Wasm client.

Question 14

How do developers implement a new light client on a chain?

Accepted Answer

Most IBC-enabled chains use the CometBFT light client implementation to integrate with the Cosmos Interchain Network. Light client implementations are also available for other ecosystems, including GRANDPA, Hyperledger Fabric, Avalanche, Solana, and more.Alternatively blockchain developers can build custom clients that implement the IBC light client specifications. The WebAssembly light client module simplifies custom-client development in any language that compiles to Wasm, including Go, Rust, C, and C++. Wasm clients are deployed as bytecode and hosted on the Wasm VM.

Question 15

What is a relayer?

Accepted Answer

A relayer is an off-chain component that acts as a message courier between connected blockchains. Relayers monitor the state of each chain to monitor for IBC-related events, and when they detect an IBC-related event, they ferry the event in an IBC packet to a destination chain. Relayers are permissionless, meaning anyone can operate one without special authorization.

Question 16

What does “trust-minimized” mean?

Accepted Answer

IBC is a trust-minimized blockchain interoperability protocol. Trust-minimized means the security of cross-chain transactions over IBC does not depend on an external third party. Instead, the security of a transaction only depends on the security of the chains that are party to the transaction. IBC minimizes trust requirements by using light clients to verify the state of counterparty chains and permissionless off-chain relayers to transport packets between chains. The relayers cannot alter data packets, and if a misbehaving relayer attempted to do so, the changed packet would be rejected by the destination chain’s light client. Light clients are self-hosted by participating chains.Learn more about How IBC is Trust-Minimized.

Question 17

How is IBC different from an externally verified bridge?

Accepted Answer

Externally verified bridges often introduce separate security models and may require custom setups for each chain pair they connect. In contrast, IBC offers a trust-minimized, permissionless approach to blockchain interoperability. It relies on light clients to verify chain states directly, rooting its security in the connected blockchains' consensus mechanisms.IBC's design allows for scalable, multi-chain connections and supports cross-chain operations beyond simple asset transfers. It is a comprehensive cross-chain communication protocol for any type of data.

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