Gasless Swaps

Gasless Swaps are for the moment when a user has a token they can trade, but not enough SOL to pay the normal Solana network fee.

Use this page to decide when Gasless belongs in the product flow, what Carbium is abstracting away, and where to go next if you need an API integration instead of the browser DEX experience.

Part of the Carbium DEX and Swap API stack.

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The User Problem

On Solana, a transaction has a fee payer. In the normal wallet flow, that fee payer needs enough lamports to cover the base fee and any priority fee before the transaction can execute.

That creates a bad first-run experience:

• a user receives USDC, BONK, SPDR, or another token
• the user wants to swap into SOL or another asset
• the wallet still needs SOL for the network fee
• the user has to leave the flow, fund SOL, and come back

Gasless Swaps are Carbium's answer to that onboarding gap. The goal is not to hide the fact that Solana fees exist. The goal is to keep the user from getting blocked by a separate SOL funding step before they can make the swap they already chose.

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How The Gasless Path Works

A gasless swap still settles on-chain. The difference is who handles the fee path and how the fee pool is kept balanced.

flowchart TB
    A["User chooses a swap<br/>in Carbium DEX"] --> B["Carbium checks whether<br/>the route supports gasless"]
    B --> C{"Gasless available?"}
    C -->|Yes| D["Carbium advances SOL<br/>from the fee pool"]
    C -->|No| E["User uses the normal<br/>SOL fee flow"]
    D --> F["User signs the swap<br/>in their wallet"]
    E --> F
    F --> G["Transaction is submitted<br/>to Solana"]
    G --> H["Swap settles on-chain"]
    H --> I["Fee pool is rebalanced<br/>from the swap economics"]

Keep the mental model simple:

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Gasless does not remove user consent. The wallet signature is still the final user-controlled checkpoint before the swap is submitted.

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When To Use Gasless

Gasless Swaps are strongest when the SOL fee requirement is the thing stopping an otherwise valid user action.

Use the normal swap path when the user already has enough SOL and there is no onboarding friction to solve.

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Browser DEX vs API Integration

There are two different jobs here. Keep them separate.

The current local API reference describes the older v1 gasless flag as valid when the output token is SOL. Do not assume every token pair, route, or request family supports gasless behavior by default.

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Product Checks Before You Enable It

Before you make Gasless the default path in a product, verify:

• the swap route supports gasless handling
• the user still sees a clear wallet confirmation
• your UI explains the expected output amount before signing
• your backend logs the quote, route, and submitted signature
• your support path distinguishes "gasless not available" from "swap failed"

If you are building for wallets or embedded apps, keep Carbium keys backend-side. Gasless is a UX decision, not a reason to expose API credentials in the client.

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Where To Go Next

Start with the path that matches the user's job:

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Ready to test the user flow? Open app.carbium.io. For the broader Carbium platform, start at carbium.io.