> For the complete documentation index, see [llms.txt](https://www.aevo.xyz/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.aevo.xyz/docs/aevo-products/aevo-builder-codes/for-builders.md).

# For Builders

Earn a fee on the trades your users make on Aevo.

## 1. Register your builder

1. Connect the account you want to receive fees with at [app.aevo.xyz](https://app.aevo.xyz). Use a dedicated account, because the fee account can't be changed later.
2. Make sure it holds at least the minimum USDC balance (currently 100 USDC).
3. Go to **Settings → Builders → Builder Dashboard**, enter your builder name and select **Register**.

You get a `builder_id` (for example `builder_0123456789abcdef`) straight away. You can also register through the API: see [Become a builder](/docs/api-reference/builder-codes/become-a-builder.md).

## 2. Get your users' approval

Each user approves your builder once, with the maximum fee you may charge them. In a web app, the smoothest way is to have the user sign the approval **inside your app**: one wallet prompt, no Aevo page and no Aevo API key needed. See [User approval](/docs/api-reference/builder-codes/user-approval.md#option-1-sign-in-your-app).

Or send them to the approval link (copy it from your Builder Dashboard):

```
https://app.aevo.xyz/builder/approve?builder_id=<builder_id>&max_fee_rate=0.0005
```

`0.0005` is 5 bps. The user reviews your builder's name and the maximum fee in the Aevo app and signs with their wallet. See [User approval](/docs/api-reference/builder-codes/user-approval.md) to build approval into your own app instead.

## 3. Attach your builder to orders

Add `builder_id` and `builder_fee_rate` to the orders your app places for a user, and include both in the order signature. You choose the rate per order, at or below the user's approved maximum and Aevo's protocol cap. See [Placing orders](/docs/api-reference/builder-codes/placing-orders.md).

## 4. Track your earnings

Open **Settings → Builders → Builder Dashboard** with your fee account to see:

* trading volume, fees earned, active, new and returning traders, and number of fills, compared with the previous period;
* maker and taker volume;
* daily volume and fee charts;
* per-market and per-trader breakdowns, and recent fills;
* a **Download CSV** export of every attributed fill;
* a lookup to check whether a given user has approved you.

The same data is available through the [Reporting API](/docs/api-reference/builder-codes/reporting-api.md). Use a read-only API key on your fee account for dashboards and accounting.

## Fees and limits

* **Perpetuals:** `builder fee = fee rate × price × contracts`.
* **Options:** `builder fee = min(fee rate × index price × contracts, premium cap × premium × contracts)`.
* Options fees are based on index notional and capped at a share of the premium, so they work differently from perpetuals. See [Perpetuals vs Options Fees](/docs/aevo-products/aevo-builder-codes/perps-vs-options-fees.md).
* **Maximum builder fee:** 5 bps on perpetuals; 3 bps of index notional on options, never more than 5% of the premium. Anything higher is rejected. A user can approve at most 5 bps.
* The live caps are also published at [`GET /builder-config`](/docs/api-reference/urls/public-api/getbuilderconfig.md).
* Fees are credited to your fee account in USDC on each fill. There is no separate payout.

## Good practice

* **Be clear with users** about the fee you charge and what your app does on their behalf.
* **Check the protocol caps** at startup rather than hardcoding them.
* **Test on testnet first** ([testnet.aevo.xyz](https://testnet.aevo.xyz)). See the [testnet guide](/docs/api-reference/builder-codes/testnet-and-reconciliation.md).

Aevo may suspend builders that mislead users or abuse the program. A suspended builder can't charge new fees.


---

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