This topic examines AI agent marketplaces and the supporting frameworks and decentralized infrastructure that let autonomous agents initiate, coordinate and settle on‑chain transactions. As of 2026, growing demand for programmatic DeFi flows, automated NFT and gaming commerce, and wallet automation has pushed activity from isolated prototypes toward marketplaces where agents can be discovered, licensed, and run against smart contracts. Key categories include no‑code agent builders (Tate‑A‑Tate, AgentGPT) that let creators design and publish agents without writing code; developer frameworks (LangChain) that provide SDKs, observability, and integrations for building reliable LLM‑powered agents; and developer productivity and hosting platforms (Replit, GitHub Copilot, Aider) that accelerate iteration, testing and deployment. Specialist offerings such as AI‑integrated crypto wallet development (e.g., Aptos‑focused implementations) illustrate how agents are being embedded in custody and transaction flows. Marketplaces for autonomous on‑chain transactions need standard interfaces, verifiable execution logs, reputation and pricing models, off‑chain compute orchestration, and secure key management (MPC/threshold signing). Trends in 2026 emphasize composability—agents as modular services—plus stronger tooling for simulation, testing, and governance to reduce economic and security risk. Interoperability between agent platforms, smart contract oracles, and gas‑efficient settlement layers is a practical priority. Understanding this space requires evaluating usability (no‑code vs. SDK), observability and safety features, wallet and key integrations, on‑chain settlement patterns, and the marketplace mechanisms that align incentives. This overview helps stakeholders choose between turnkey agent marketplaces and developer‑centric frameworks when building or procuring autonomous on‑chain transaction capabilities.