TRON GasFree: Gasless TRC20 Transfers

GasFree lets users send TRC20 tokens (e.g. USDT) on TRON without holding TRX for gas. The transfer fee is paid in the transferred token itself, and a GasFree service provider broadcasts the transaction on-chain on the user's behalf in exchange for that token fee.

How it works

Each user address has a deterministic GasFree custody address — a smart-contract account derived from the user's address and a per-network controller contract (via TVM CREATE2). Tokens held at this custody address are eligible for gasless transfers.

1. Activate the TRON platform coin with a tron_gasless_provider, and optionally a per-token gasless constraint. Activation returns each address's gasfree_address (see enable_eth_with_tokens).
2. Fund the GasFree custody address with the token you want to transfer gaslessly.
3. Withdraw with fee_method: "gasless" (withdraw). The framework computes the provider fee, signs a TIP-712 PermitTransferMessage authorizing {token, serviceProvider, user, receiver, value, maxFee, deadline, nonce}, and returns the signed authorization (a relay_type: "tron_gasfree" payload) plus a TronGasless fee breakdown.
4. Submit the signed authorization to the provider via send_raw_transaction (passed as a tx_json object). The provider pays the TRX gas, settles the transfer on-chain, and the call returns a trace_id.
5. Track the transfer with gasless::trace_status (one-off poll) or stream::gasless_trace::enable (live updates) using the trace_id.

Fees

Fees are paid in the transferred token, not in TRX:

• transfer_fee — the provider's fee to broadcast and settle the transfer.
• activation_fee — a one-time fee, charged in the token, when the GasFree custody address is inactive and must be activated on its first transfer (omitted otherwise).
• total_token_fee — the total charged in the token (transfer_fee + activation_fee).

You can cap the fee you are willing to pay with the gasless.max_fee option at withdraw time (which is bound into the signed permit), or at activation time with a per-token gasless.transfer_max_fee. Set gasless.fallback_to_native: true to fall back to a normal TRX-paid transfer when a gasless transfer is unavailable.

Providers: direct vs Komodo proxy

The service field of the tron_gasless_provider selects how the node authenticates to the gasless backend:

• gas_free — the node calls the public GasFree API directly, authenticating each request with your own HMAC-SHA256 api_key/api_secret.
• komodo_proxy — requests are routed through the Komodo proxy, which holds the GasFree credentials on your behalf. No API secret is stored on the node; the node authenticates to the proxy with its libp2p key.

Related methods

• enable_eth_with_tokens / task::enable_eth::init — activate TRON with a GasFree provider.
• withdraw — create a gasless transfer (fee_method: "gasless").
• send_raw_transaction — submit the signed transfer to the provider.
• gasless::trace_status — poll a transfer's status.
• stream::gasless_trace::enable — stream live transfer status.