Ship gasless transactions and session keys in one integration
ERC-4337 bundler, transaction relayer, and fee sponsorship across Ethereum and Solana. Deploy smart accounts, sponsor transactions, and relay UserOperations at scale.
No credit card required • Free testnet accounts
10M+ transactions by 50+ customers.
Read their stories →
Fee sponsorship across Ethereum and Solana
Sponsor transaction fees for your users on any supported chain. Openfort paymasters handle gas sponsorship on Ethereum and fee sponsorship on Solana—users interact with your app without ever holding native tokens.
View docsERC-4337 bundler and transaction relayer
Openfort runs a high-performance ERC-4337 compliant bundler that processes UserOperations reliably across 25+ chains. Our transaction relayer handles nonce management, gas estimation, and resubmission so your backend can fire-and-forget.
View docs
Higher is better (normalized to 100%)
Account abstraction for the next billion users
Full-stack infrastructure for ERC-4337 and EIP-7702 with gas sponsorship and session keys.
Gas Sponsorship
Sponsor gas for your users with configurable policies. Users never need to hold native tokens.
Transaction Batching
Combine multiple operations into a single transaction for better UX and lower costs.
Permissions
Grant temporary, scoped permissions to eliminate signing popups during gameplay or app usage.
Smart Accounts
Programmable accounts with in Ethereum and Solana for advanced features like social recovery.
Nonce management
Manage nonces for your wallets automatically.
Multisig and social recovery
Manage multisig and social recovery for your wallets.
From developers that use Openfort
"Game studio reaches 150K players with gasless transactions"
From launch to 150,000 active players using session keys for seamless in-game transactions without signing popups.
Moonlit Games
"GFAL increases marketplace engagement by 3x with gas sponsorship"
Sponsored gas for all marketplace transactions simplified the user experience and drove 3x more engagement.
GFAL
"Gaimin leverages smart accounts for best-in-class UX"
Openfort smart wallets have been instrumental to offer gasless transactions and batched operations to their users.
Gaimin
"Game studio reaches 150K players with gasless transactions"
From launch to 150,000 active players using session keys for seamless in-game transactions without signing popups.
Moonlit Games
"GFAL increases marketplace engagement by 3x with gas sponsorship"
Sponsored gas for all marketplace transactions simplified the user experience and drove 3x more engagement.
GFAL
"Gaimin leverages smart accounts for best-in-class UX"
Openfort smart wallets have been instrumental to offer gasless transactions and batched operations to their users.
Gaimin
Integrate relayers and fee sponsorship in minutes
Multi-platform SDKs
React, React Native, Unity, and server-side SDKs for any platform.
Dedicated Support
Work directly with our engineering team to ship your AA integration.
Flexible Architecture
Use our hosted infrastructure or self-host with OpenSigner for full control.
Learn more about account abstraction
Technical guides on ERC-4337, smart accounts, gas sponsorship, and session keys
Technical Dive: Gas Sponsorship via Paymasters
Deep dive into ERC-4337 paymasters: how gasless transactions work, off-chain vs. on-chain paymaster logic, and sponsorship policies.
Technical Dive: Key Permissions for Accounts
Comprehensive guide to onchain and offchain permission systems for smart accounts: spending limits, contract whitelisting, and session keys.
EOA vs Smart Wallets in 2026: What Builders Need to Know
Breakdown of EOAs vs. smart wallets vs. Smart EOAs (EIP-7702), covering gas abstraction, social recovery, and deployment costs.
Parallelizable Paymasters in EntryPoint v0.9
Technical breakdown of EntryPoint v0.9: async paymaster signing, ERC-20 gas sponsorship, and parallel transaction processing.
Understanding Native Account Abstraction in RIP-7560
How RIP-7560 integrates account abstraction directly into Ethereum L2 protocol, making smart contract wallets first-class citizens.
EIP-3074 to EIP-7702: Advancing Ethereum Account Abstraction
The evolution from EIP-3074 to EIP-7702, explaining how EOAs can temporarily act as smart contracts for enhanced flexibility.
Frequently Asked Questions
Can't find your answer?
Account abstraction (ERC-4337) replaces traditional externally owned accounts (EOAs) with programmable smart accounts. This enables fee sponsorship (users don't need native tokens), session keys (no signing popups), transaction batching (multiple operations in one click), and social recovery. Openfort provides the full infrastructure—smart accounts, 4337 bundler, transaction relayer, and paymaster—so you can build Web3 apps that feel like Web2.
ERC-4337 introduces smart accounts as a new account type with a separate mempool and bundler infrastructure. EIP-7702 (formerly EIP-3074) lets existing EOAs temporarily delegate to smart contract code, getting AA features without deploying a new account or migrating assets. Openfort supports both standards, so you can choose the right approach for your users—new smart accounts for new users, or EIP-7702 upgrades for existing wallet holders.
Openfort paymasters let you sponsor transaction fees for your users on both Ethereum and Solana. On EVM chains, the paymaster handles gas sponsorship so users never need ETH. On Solana, fee sponsorship covers transaction fees natively. You can configure policies to sponsor all transactions, restrict to specific contracts, set daily/monthly limits per user, or require users to pay in ERC-20 tokens.
Session keys are temporary, scoped permissions granted to your app. Instead of asking users to sign every transaction, you request a session key upfront with specific limits (e.g., "play this game for 24 hours, max 100 transactions, only these contracts"). Your app then uses the session key to submit transactions on behalf of the user within those bounds—no more popups interrupting gameplay or purchases.
Yes, in two ways. First, Openfort smart accounts can be controlled by an EOA signer, so MetaMask users sign transactions that the smart account executes (getting gas sponsorship and batching). Second, with EIP-7702 support, EOAs can directly opt-in to smart account features without changing addresses. This lets you serve both embedded wallet users and existing wallet holders with the same AA infrastructure.
Openfort supports 25+ EVM networks including Ethereum, Polygon, Arbitrum, Optimism, Base, Avalanche, BNB Chain, and Solana. Our 4337 bundler and paymaster infrastructure is deployed natively on each EVM chain, while Solana has dedicated fee sponsorship support. The transaction relayer handles nonce management and resubmission across all chains for reliable delivery.