Since launching Relayers and Monitor tools as part of the Defender development suite in 2022, thousands of blockchain developers and industry’s leading protocols have integrated them into their stack.
40+ million transactions have been executed through Relayers, and 45 million alerts have been triggered via Monitor, supporting developers across 70+ networks.
Today, we’re building on that widespread adoption by releasing alpha Open Source versions of Relayers and Monitor. By making these tools open source, we are giving developers deeper customization, greater flexibility, the option to self-host, and the freedom to integrate them into their workflows as they wish.
Open source has always been an integral part of OpenZeppelin. As we’ve seen with our Solidity Contracts Library, providing the community with the best open source tools and developing them in the open is key to foster sustained innovation, drive industry standards, and thus accelerate the development of efficient blockchain applications.
Open Source Relayers
Relayers enable programmable transaction execution, handling automatic gas estimation, transaction submission, queue management, and webhook notifications, removing the complexities of transaction management. You can use Open Source Relayers for a wide range of scenarios, for example:
- Automating smart contract transactions based on specific triggers.
- Sponsoring gasless transactions for a seamless user experience.
- Executing onchain updates based on offchain data.
- Scheduling recurring wallet transfers.
- Automating onchain security measures for your protocol.
- Building custom workflows with complete logic and flexibility.
We’re initially releasing an alpha version for EVM networks, and we welcome developers to try it out and provide feedback. We aim to deliver a production-ready tool later this year.
Although you’re free to adapt Relayers for any EVM chain, we’re currently including extended network configurations (like price refresh and fee estimation) only for Ethereum and OP Mainnet. We’ll add built-in support for Base, Arbitrum, Polygon, BNB Chain, ZKsync, Scroll, and more in the weeks ahead.
Check out the documentation and our first release to start experimenting, and join us on Telegram to share your feedback and suggest which chains should be supported next.
Expanding Relayers to Solana
We are also announcing an extension of Relayers to the Solana network. In this alpha release, Relayers have been tailored to Solana’s performance-driven environment, handling key operations like transaction creation, fee estimation, and fee payments. Additionally, Solana Relayers implement a standardized RPC API interface that enables users to relay transactions and pay fees using other supported tokens instead of SOL, or have the relayer sponsor the transaction entirely.
With over $22 billion in onchain assets, the Solana ecosystem is the second largest by DeFi Total Value Locked at over $11 billion (Source: DeFiLlama). The ecosystem continues to attract a new surge of developers, and we’re excited to serve them with Open Source Relayers that can enhance their development experience.
Open Source Monitor
Monitor provide critical visibility into onchain activities, allowing developers and users to detect threats, track authorized functions, and set up real-time alerts or automated responses. By integrating monitor alerts with communications tools tools like Slack, Telegram, Discord, PagerDuty, and Opsgenie, Open Source Monitor helps you keep an eye on your protocol and funds without building everything from scratch:
- Monitoring ownership and role checks by tracking events like ownership transfers, contract pauses, or token mints.
- Monitoring DeFi, gaming, infrastructure, and more protocols’ key events by watching pool balances, asset movements, or transaction volumes in real time.
- Integrating user-friendly alerts through your preferred channels.
- Identifying suspicious or unauthorized activity early and automatically responding.
- Combining with Relayers to trigger onchain actions whenever a Monitor event occurs.
Currently, we’re releasing the alpha version of Open Source Monitor for EVM networks with a basic feature set, enabling developers to try them out while we gather feedback and expand functionalities. We aim to deliver a production-ready release later this year.
Explore the documentation and our first release to start experimenting, and share your feedback on Telegram.
Expanding Monitor to Stellar
As part of our efforts to expand OpenZeppelin’s developer tooling into new ecosystems, we’re releasing an alpha version of Open Source Monitor tailored for Stellar. While the core Monitor functionalities remain the same, the Stellar version includes specialized setup configurations for Stellar’s unique architecture. Detailed instructions can be found in the documentation.
Stellar is a high-throughput, low-fee Layer 1 blockchain focused on real-world use cases, including payments, tokenization, and on/off ramps. Over time, it has proven the viability of onchain financial solutions: notably, Franklin Templeton’s onchain fund now holds more than 68% of its assets on Stellar, boasting over $475 million (Source: DeFiLlama).
We’re excited to drive more efficient and secure development on Stellar, and together with the OpenZeppelin Stellar Contracts Library, we aim to make the development experience faster, safer, and easier.
Choosing Between Open Source and Defender
If you’re already using Defender, rest assured, nothing changes for you. By open sourcing Relayers and Monitors, we simply want to give developers the freedom to build in whichever way suits them best: a hosted, all-in-one product like Defender, or a self-hosted setup with more flexibility and customization.
Although Open Source Relayers and Monitors share many of the same use cases as Defender, they differ fundamentally in how they’re deployed and managed, catering to needs that can’t be met by a fully hosted environment.
Choose whichever best aligns with your workflow, compliance requirements, and technical strategy. Whether you prefer an open source approach for maximum control or the fully hosted convenience of Defender, OpenZeppelin aims to empower your onchain development each step of the way.
More Open Source Tools to Come
Monitor and Relayers are just the beginning of our efforts to release open source tooling that can help developers to build, secure, and operate their application with greater flexibility, on any chain.
Building on the huge adoption of the OpenZeppelin Contracts Libraries, which power more than $23 billion in total value transferred, our vision is to create an open ecosystem where developers can pick and choose building blocks and customize them to their unique needs.
With Open-Source Monitors and Relayers now in alpha, we can’t wait to see how the community experiments, integrates, and improves these tools. We plan to extend our open source approach to more developer tooling in the future, continually improving the developer experience for every blockchain ecosystem.
Check out the documentation and the alpha release of Open Source Relayers (EVM & Solana).
Check out the documentation and the alpha release of Open Source Monitor (EVM & Stellar).
Join the official OpenZeppelin Telegram to share your experience with Relayers and Monitor, help improve the tools, and connect with other builders.
