Overview
Gasless transactions let users submit transactions with zero sFUEL in their wallet by performing a small Proof-of-Work (PoW) upfront. The PoW yields a “magic number” that the chain accepts in place of a gas payment, keeping UX frictionless even when wallets are empty.
Exploring Proof of Work
SKALE’s PoW is light enough for clients but costly enough to discourage spam. Wallets compute a magic number tied to sender, nonce, and gas limit, proving work before the chain executes the transaction—even with zero sFUEL on hand.
Understanding Magic Numbers
The magic number represents the gasPrice value in the transaction. The client calculates it with PoW so the chain can verify work without needing a token balance. This keeps gasless fully EVM-compatible—no protocol forks or custom wallets required.
Proof of Work Algorithm
- Generate a 256-bit
X (the magic number) using sender, nonce, and gas limit.
- Compute available “free gas” using the chain’s PoW difficulty.
- If free gas covers the estimated gas, submit the transaction with
gasPrice = X and gasLimit = freeGas(X).
- Otherwise, repeat until a valid magic number is found.
- ⊕ is the bitwise XOR operator
- KECCAK256(SHA3) is the hashing algorithm that should be used
MetaMask and other popular browser wallets with which SKALE Chains are compatible do not always support gasless transactions. This is
because the magic number generated is generally very, very large and the wallets either have a limitation on the number size or on the lack of gas in the user wallet.
Popular Use Cases
- Invisible onboarding – Let users transact without ever seeing gas prompts.
- Self-serve sFUEL – Avoid server-side faucets; the client can prove work and proceed.
- Extra spam resistance – Pair with zero-gas chains to add another layer of protection.
| Name | Description | Language |
|---|
| @eidolon-labs/gasless | Generate magic numbers using SKALE Proof of Work with Rust | JS/TS/Rust |
| skale.dart | Generate magic numbers with Dart | Dart |
| skale-gas-miner | Generate magic numbers in Unity | C++/C# |
