Overview
Traditionally, sending blockchain transactions onchain has been painful:- You need to fund wallets with native gas tokens, creating onboarding friction
- Network congestion and fee spikes can cause transactions to stall or get dropped altogether
Supported chains
EVM (sponsored):- Base - eip155:8453
- Polygon - eip155:137
- Ethereum - eip155:1
- Base (Sepolia) - eip155:84532
- Polygon (Amoy) - eip155:80002
- Ethereum (Sepolia) - eip155:11155111
- Solana mainnet - solana:mainnet
- Solana devnet - solana:devnet
Interested in another chain? Reach out to us!
To access sponsored transactions, ensure that Gas Sponsorship is first enabled within your Turnkey dashboard. Then set
sponsor: true and update the caip2 parameter with the corresponding chain identifier.Concepts
Gas sponsorship (aka gas abstraction, gasless transactions, fee abstraction)
A single endpoint lets you toggle between standard and sponsored transactions. With sponsorship enabled, your users never need to hold native tokens to pay transaction fees — Turnkey covers them. Setsponsor: true to enable sponsorship, or sponsor: false to have fees paid by the sender’s wallet.
Either way, Turnkey handles construction, signing, broadcast, and status monitoring. The sponsor flag only controls who pays the fee.
Construction and Broadcast
EVM
A successful EVM transaction requires:- Transaction construction: assembling the payload (recipient, value, calldata)
- Nonce: set correctly to order transactions and prevent conflicts
- Gas and tip fee: estimated to ensure inclusion even during network congestion
- Signature: cryptographically signing the transaction with the sender’s private key
- Broadcast: submitting the signed transaction to the network and monitoring for inclusion
ethSendTransaction. Whether or not you use sponsorship, you pass through minimal payloads and we take care of the rest. We auto-fill any fields you omit.
This endpoint supports arbitrary EVM transactions — not just simple sends. You can interact with smart contracts, deploy contracts, or execute any valid EVM operation.
Solana
A successful Solana transaction requires:- Transaction construction: assembling the list of instructions (program, accounts, data)
- Recent blockhash: fetched and attached at broadcast time to ensure the transaction is valid
- Compute unit limit: estimated and set to prevent failed transactions due to insufficient compute
- Priority fee: set to ensure timely inclusion under current network conditions
- Signature: cryptographically signing the transaction with the sender’s private key
- Broadcast: submitting the signed transaction to the network and monitoring for confirmation
solSendTransaction. Whether or not you use sponsorship, you pass through a minimal payload and we manage the rest.
On Solana, fee sponsorship and rent sponsorship are separate.
Sponsor Solana Rent is disabled by default and must be enabled in the dashboard before
Turnkey will pre-fund rent for account creation. If created accounts are later
closed, refunded rent can go back to the signer rather than the sponsor. See
Solana Rent Sponsorship. For payer behavior,
static-key requirements, and account-creation caveats in sponsored flows, see
Solana transaction construction for sponsored flows.Transaction status and enriched errors
After you send a transaction, Turnkey monitors its status until it fails or is confirmed on-chain.Transaction Statuses
The following statuses apply to both EVM and Solana transactions:| Status | Description |
|---|---|
| INITIALIZED | Turnkey has constructed and signed the transaction and prepared fees, but it has not yet been broadcast. |
| BROADCASTING | Turnkey is actively broadcasting the transaction to the network and awaiting inclusion. |
| INCLUDED | The transaction has been included in a block (EVM) or confirmed on-chain (Solana). |
| FAILED | The transaction could not be included on-chain and will not be retried automatically. |
EVM Smart Contract Transaction Errors
For EVM transactions that revert, Turnkey runs a simulation to produce structured execution traces and decode common revert reasons — giving you actionable error messages instead of opaque hex data.| Error type | Description |
|---|---|
| UNKNOWN | The transaction reverted during on-chain execution or simulation, but the revert reason could not be decoded (e.g. missing ABI or unverified contract). |
| NATIVE | The transaction reverted due to a built-in Solidity error, such as require(), assert(), or a plain revert(). |
| CUSTOM | The transaction reverted due to a contract-defined custom error declared using Solidity’s error keyword. |
These error types describe how an EVM smart contract reverted during on-chain execution or pre-flight simulation. Turnkey application-level errors (e.g. signing failures, policy rejections) are not classified here and are instead surfaced via
Error.Message.Spend limits
Turnkey provides tools to manage your gas sponsorship budget. You configure USD fee limits at two levels: across all orgs and per sub-org. This gives you control over both total spend and per-user spend. You can set limit values and time windows through the dashboard. You can query current gas usage and limits through our endpoints.Policy engine
You can write policies against both sponsored and non-sponsored transactions using Turnkey’s policy DSL:- EVM: use the
eth.txnamespace - Solana: use the
solana.txnamespace
Billing
Turnkey passes transaction fee costs through to you as a line item at the end of the month. You pay based on the USD value of fees at time of broadcast; Turnkey internalizes the inventory risk of token price changes. Our battle-tested fee estimation aims to be cost-efficient while ensuring quick transaction inclusion.Advanced
Gas sponsorship smart contracts (EVM)
We could not find a satisfactory setup for gas sponsorship contracts that were both fast and safe, so we made our own. The contracts are open source and you can check them out on GitHub. Based on our benchmarks, these are the most efficient gas sponsorship contracts on the market. They achieve this through optimized logic, calldata encoding, and extensive use of assembly, which reduces gas overhead per sponsored transaction. The result: lower costs for you and faster execution for your users.Security
Some gas sponsorship setups by other providers are subject to replay attacks. If a malicious actor compromises the provider infrastructure, they can replay the gas sponsorship request multiple times with different nonces to create multiple transactions from a single request. At Turnkey, we never cut corners on security: we perform transaction construction in enclaves, and as long as the request includes the relevant nonce or blockhash, only one transaction can be created from it. Since the user’s authenticator signs requests and the enclave verifies signatures, a malicious actor cannot modify or replay the request. This is in line with Turnkey’s core system design principle: everything can be compromised outside of the enclaves and funds will still be safe. By default, our SDKs include a special gas station nonce for sponsored transaction requests.RPCs
Turnkey’s send transaction and transaction status endpoints eliminate the need for third-party RPC providers. You save costs and reduce latency because we holistically incorporate internal data and minimize external calls.Next Steps
For implementation guides, see:- Sending Sponsored EVM Transactions (React) - Using
@turnkey/react-wallet-kit - Sending Sponsored Solana Transactions (React) - Using
@turnkey/react-wallet-kit - Sending Sponsored Transactions - Using
@turnkey/coredirectly