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

# DBC Rate Limiter

> Learn how DBC rate limiter fees increase with buy size and single-swap validation to help protect launches from oversized early buys.

The DBC rate limiter is a base fee mode that increases the fee as buy size increases.

It is designed for launches where the main risk is not only who buys first, but how much they buy. Small buys can pay the starting fee, while larger buys pay a higher average fee during the limiter window.

## How It Works

The rate limiter uses four core settings.

| Setting              | Product Meaning                                                  |
| -------------------- | ---------------------------------------------------------------- |
| Cliff fee            | The starting fee for buys up to the reference amount.            |
| Reference amount     | The trade size unit used to calculate fee tiers.                 |
| Fee increment bps    | How much the fee increases for each additional reference amount. |
| Max limiter duration | How long the limiter stays active after launch.                  |

In product terms, the rate limiter behaves like fee brackets.

```text theme={"system"}
Small buy  -> base fee
Medium buy -> higher average fee
Large buy  -> even higher average fee
```

## Example

Assume:

* Reference amount: 1 SOL.
* Cliff fee: 1%.
* Fee increment: 1%.

Then:

| Buy Size | Product Behavior                 |
| -------- | -------------------------------- |
| 1 SOL    | Pays the starting fee.           |
| 2 SOL    | Pays a higher average fee.       |
| 3 SOL    | Pays a higher average fee again. |

This does not block large buys. It makes large buys more expensive during the configured launch window.

It also helps protect the fee design at the transaction level. When the limiter is active, the program validates single-swap behavior for the pool so traders cannot easily split one large buy into multiple swaps inside the same transaction.

For exact-in swaps, the limiter derives the fee from the included input amount. For exact-out swaps, it derives the fee from the excluded amount and performs a conservative reverse calculation, so different swap modes can produce slightly different effective limiter behavior.

## Requirements

Rate limiter mode has important constraints.

| Requirement                  | Product Meaning                                                                                                               |
| ---------------------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| Quote Token collect fee mode | Rate limiter is designed for quote-token fee collection.                                                                      |
| Buy-side behavior            | It applies to quote-to-base buys, not regular sell-side behavior.                                                             |
| One base fee mode            | It is mutually exclusive with the fee scheduler modes.                                                                        |
| Max duration                 | The limiter duration is capped at 12 hours.                                                                                   |
| Fee bounds                   | The starting fee must stay within DBC's bonding phase fee bounds.                                                             |
| Single-swap validation       | Active rate limiter trades are checked so a transaction cannot bundle multiple swaps for the same pool to bypass the limiter. |

The 12-hour cap is represented as `43,200` seconds for timestamp activation or `108,000` slots for slot activation. If `reference_amount`, `max_limiter_duration`, and `fee_increment_bps` are all zero, rate limiter mode behaves like a fixed cliff-fee mode.

<Warning>
  Rate limiter should be used when the launch specifically wants buy-size-sensitive fees. If the launch only needs time-based fee decay, use a linear or exponential scheduler instead.
</Warning>

## Why Use Rate Limiter

<CardGroup cols={2}>
  <Card title="Discourage Oversized Buys" icon="scale-balanced" iconType="solid">
    Very large launch buys can become progressively more expensive.
  </Card>

  <Card title="Protect Early Distribution" icon="shield" iconType="solid">
    The fee slope can reduce the advantage of a single large first mover.
  </Card>

  <Card title="Preserve Small Buyer Access" icon="users" iconType="solid">
    Smaller buys can still use the starting fee while larger buys move into higher tiers.
  </Card>

  <Card title="Short Launch Window" icon="hourglass-half" iconType="solid">
    The limiter is meant for early launch protection, not permanent pool behavior.
  </Card>
</CardGroup>

## When To Choose It

Choose rate limiter when:

* The launch expects aggressive large buys.
* The goal is to make large buys less attractive without fully preventing them.
* The launch wants fee protection based on size rather than time.
* Fees should return to the base level after the limiter window ends.