Expanding Stellar Support with Relayer Service

OpenZeppelin Relayer technology has provided transaction infrastructure across EVM, Solana, and Stellar networks since its open source release. Now, Stellar is making that same infrastructure available to developers as a hosted service: production-grade transaction management without provisioning servers, managing deployments, or maintaining uptime.

Extending our work with Stellar Development Foundation

Over the past year, as part of our partnership with Stellar Development Foundation, we've delivered audited, battle-tested contracts and a suite of open source tools for the Stellar ecosystem, including the OpenZeppelin Stellar Contracts library, a self-hosted Relayer, Monitor for real-time smart contract activity, the Soroban Security Detectors SDK for static analysis, and a UI Builder for scaffolding contract frontends.

The Stellar Relayer service extends that work as a hosted transaction relay for the Stellar network, built on secure cloud infrastructure.

Designed for teams building DeFi protocols, stablecoins, agentic payments, institutional workflows, consumer apps, and more, the Relayer service provides full Soroban smart contract functionality, including contract deployment and invocation, XLM payments, and XDR operations, with automatic fee management.

What’s included

Sponsored Transactions

Users submit transactions without holding XLM. The Relayer wraps each transaction in a fee-bump envelope signed by a dedicated fund account, covering all network fees on the user's behalf.

Secure Key Management

Every transaction is signed through isolated key management: private keys are never exposed to application code. Each channel account's keypair is managed independently, and the fund Relayer's signing key is separated from the transaction processing pipeline.

High-Throughput Parallel Processing with the Channels Plugin

The Channels plugin is a parallel transaction processing system designed to optimize Stellar's transaction throughput. It eliminates the sequence number bottlenecks inherent to Stellar's account-based sequencing model by maintaining a pool of independent channel accounts. Each transaction acquires a channel, executes in parallel, and releases it back on completion.

Transaction Lifecycle Management

As part of its built-in functionality, the Relayer automatically tracks every transaction through submission, confirmation, and failure, with automatic fee bumping, retry logic, and webhook callbacks on resolution.

Configurable Network Policies

The Relayer service provides the ability to configure transaction processing rules per Relayer instance. These rules, including allowlists, rate limits, and fee policies, are enforced by the Relayer at the infrastructure level, not at the application level.

Plugin System

The Relayer Service supports plugins to extend the functionality of the Relayer. Plugins are TypeScript functions running in the Relayer server that can include any arbitrary logic defined by the Relayer operator.

The plugin system supports: Handler Pattern, TypeScript Support, Plugin API, Key-Value Storage, HTTP Headers, Route-Based Invocation, Docker Integration, and Comprehensive Error Handling.

Supported Use Cases

• DeFi Protocols: The Relayer service handles Soroban smart contract execution at scale, with parallel processing and automatic fee management for high-volume operations on Stellar.
• X402 Agentic Payments: Built as a dedicated plugin, the x402 Facilitator handles payment verification, onchain settlement, and authorization entry validation for applications accepting Stellar assets such as USDC for API access or content, with optional Channels plugin integration for high-throughput settlement.
• Institutional Workflows: For teams running payment infrastructure, tokenized asset operations, and settlement systems, it provides reliable, auditable transaction submission on Stellar with secure key management built in.
• Consumer Apps: Sponsored transactions remove the requirement for users to hold XLM, enabling practical onboarding for applications targeting users with no prior exposure to Stellar.
• Backend Automation: Scheduled operations, event-driven automation, and batch processing on Stellar are handled without the need for custom transaction reliability engineering.

Integrate the Relayer Service into your Stellar app

Full documentation and integration guides are available at docs.openzeppelin.com/relayer/1.4.x/guides/stellar-channels-guide.

For networks looking to sponsor the relay service, reach out to us directly to discuss your requirements.

FAQs

What is the OpenZeppelin Relayer Service for Stellar? 
A production-grade transaction relay service for the Stellar network. It handles signing, fee management, nonce ordering, and failure recovery without requiring teams to provision servers, manage deployments, or maintain uptime.

How is the Relayer Service different from the open source OpenZeppelin Relayer?
The open source Relayer is self-hosted, teams deploy and operate it themselves. The Relayer Service provides the same core functionality, hosted by OpenZeppelin.

What is the Channels plugin? 
A parallel transaction processing system that uses a pool of independent channel accounts to eliminate Stellar's sequence number bottlenecks, enabling high-throughput Soroban contract execution.

What is the x402 Facilitator plugin?
A dedicated plugin that enables x402 payment facilitation on Stellar, handling payment verification, on-chain settlement, and authorization entry validation for applications accepting Stellar assets such as USDC for API access or content.