> ## Documentation Index
> Fetch the complete documentation index at: https://docs.velumx.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Economics

# Protocol Economics

## Fee Calculation

VelumX uses a real-time pricing oracle to calculate infrastructure fees in the user's chosen SIP-010 token.

### The Formula

$Infrastructure\ Fee = \frac{Gas\ Cost_{STX} \times STX/USD \times (1 + Markup)}{Token/USD}$

| Variable      | Description                                                       |
| :------------ | :---------------------------------------------------------------- |
| **Gas Cost**  | Estimated STX fee for the transaction (typically 0.001–0.005 STX) |
| **STX/USD**   | Real-time rate from Bitflow, ALEX, CoinGecko oracles              |
| **Markup**    | Developer-configurable percentage on top of base cost             |
| **Token/USD** | Exchange rate of the fee token (e.g. aeUSDC, sBTC)                |

The `estimateFee()` SDK call returns `maxFee` — the maximum the user will pay. The relayer guarantees this cap.

## Sponsorship Policies

### DEVELOPER\_SPONSORS

The developer's relayer pays STX gas. Users pay nothing.

* **Cost to developer**: STX consumed from their relayer balance
* **Revenue**: None — this is a subsidized UX
* **Best for**: Zero-friction onboarding, day-0 users with empty wallets

### USER\_PAYS

The user pays a SIP-010 token fee. The developer's paymaster contract collects it atomically.

* **Cost to developer**: STX consumed from their relayer balance (for gas sponsorship)
* **Revenue**: The SIP-010 fee goes to the developer's relayer address. Developers can configure a markup percentage to earn above the base gas cost.
* **Best for**: Sustainable fee models, existing DeFi users who hold stablecoins

## Revenue Model for Developers

With USER\_PAYS, developers can turn gas into a revenue stream:

1. User pays `fee_amount` in aeUSDC (or any SIP-010 token)
2. Fee goes directly to the developer's relayer address
3. Developer configures markup in the Dashboard (e.g. 10% above base gas cost)
4. Developer exports their relayer private key to withdraw accumulated fees

## Settlement Assets

Any SIP-010 token can be used as a fee token — the relayer validates supported tokens per API key policy. Common choices:

* **aeUSDC / USDCx**: Stablecoin settlement — predictable fee amounts
* **sBTC**: Bitcoin-native fee payment
* **STX**: Native token (for projects where users hold STX but want gasless UX)
* **Custom tokens**: Any SIP-010 token your users hold