Tendermint Overview: Architecture, Design Principles, and Core Modules

The article introduces the rapid growth of public‑chain projects and the need for cross‑chain interoperability, highlighting Cosmos as a representative example. It explains that Cosmos builds on the core technology Tendermint to achieve inter‑network value transfer.

What is Tendermint? Tendermint is described as software that securely and consistently replicates an application across many machines, tolerating up to one‑third Byzantine failures. It consists of two main components: the Tendermint Core consensus engine and the Application Blockchain Interface (ABCI), which allows applications to be written in any programming language.

The core components are:

Tendermint Core : the BFT consensus engine that orders transactions and ensures identical logs on all non‑faulty nodes.

ABCI : a generic interface that lets applications process transactions in any language via a socket (TSP or gRPC) server.

Design Principles focus on ease of use, understandability, high performance, and applicability to various distributed applications. Tendermint separates the consensus layer from the application layer, enabling modular blockchain development.

The blockchain architecture is divided into three layers:

Networking layer – handles transaction propagation and data synchronization.

Consensus layer – ensures state consistency across validators.

Application layer – executes the actual transaction logic.

Typical issues with monolithic blockchains (code reuse difficulty and language lock‑in) are addressed by Tendermint’s modular design.

Consensus Algorithm – Tendermint implements a Byzantine Fault Tolerant (BFT) Proof‑of‑Stake algorithm. Validators propose blocks in turn, and a block is committed only after >2/3 of validators pre‑commit. The protocol includes lock‑step mechanisms to prevent double‑commit when < 1/3 of validators are Byzantine.

Compared with classic PBFT, Tendermint differs in its handling of Byzantine weight (based on voting power) and its dynamic validator set.

P2P Network adopts a Bitcoin‑like peer discovery mechanism with an address book. Connections are secured using a Station‑to‑Station (STS) authenticated key‑exchange based on ED25519 keys and a series of hash‑derived challenges.

Application Example – Tendermint ships with simple ABCI demos (counter and kvstore). The kvstore demo can be started with the following commands:

tendermint init
abci-cli kvstore
tendermint node

More complex applications, such as an Ethereum‑like platform (e.g., Ethermint), integrate go‑ethereum with an ABCI server.

Workflow – Clients broadcast transactions via RPC (broadcast_tx_commit). The mempool validates them with CheckTx, the consensus engine orders and packages them into blocks, and the ABCI Application processes DeliverTx and Commit messages, finally returning results to the client.

Conclusion – Understanding Tendermint enables rapid development of custom blockchains without dealing with consensus or P2P details, facilitates integration with the Cosmos cross‑chain ecosystem, and supports applications written in any language.