# BRC20

When selecting the token pair and clicking to add liquidity, if it is a BRC20 token, you need to first request the pre-add/create interface.

## POST /brc20swap/v2/pre\_add\_liquid

> Pre-add liquidity

```json
{"openapi":"3.0.1","info":{"title":"Backend API","version":"1.0.0"},"servers":[{"url":"https://api-testnet4.dotswap.app","description":"Swap test"},{"url":"https://api.dotswap.app","description":"Swap official"}],"security":[],"paths":{"/brc20swap/v2/pre_add_liquid":{"post":{"summary":"Pre-add liquidity","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"tick1":{"type":"string","title":"Coin name"},"tick2":{"type":"string"},"amount_1":{"type":"string","title":"Injection amount"},"amount_2":{"type":"string"},"tick_1_inscription_ids":{"type":"array","items":{"type":"string"},"title":"Inscription ID","description":"Used when recharging BRC20"},"tick_2_inscription_ids":{"type":"array","items":{"type":"string"}},"payer_ord_addr":{"type":"string","title":"Address"},"payer_btc_addr":{"type":"string"},"payer_pub_key":{"type":"string"},"fee_rate":{"type":"string","title":"Fee rate"},"slipper":{"type":"string","title":"Slippage"}},"required":["tick1","tick2","amount_1","amount_2","slipper","tick_1_inscription_ids","tick_2_inscription_ids","payer_ord_addr","fee_rate","payer_btc_addr","payer_pub_key"]}}}},"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"object","properties":{"code":{"type":"integer","additionalProperties":false},"msg":{"type":"string","additionalProperties":false},"data":{"type":"object","properties":{"tx_size":{"type":"integer","title":"Tx size","additionalProperties":false},"ins_contain_sats":{"type":"integer","title":"The sum of satoshis in the input inscriptions","additionalProperties":false},"vins":{"type":"array","items":{"type":"string","additionalProperties":false}},"usr_cnt":{"type":"integer","additionalProperties":false},"net_fee":{"type":"integer","title":"Network fee","additionalProperties":false},"check_sum":{"type":"string","title":"Checksum","additionalProperties":false}},"required":["net_fee","check_sum","tx_size","usr_cnt","vins"]},"req_id":{"type":"string","additionalProperties":false}},"required":["code","msg","data","req_id"]}}},"headers":{}}}}}}}
```

## Important Notes

{% hint style="info" %}

1. The result returned from this interface should be passed as is to the `create_add_liquid_psbt` interface.
2. Since liquidity is added based on a ratio and BRC20 needs to be inscribed first, creating BRC20-BRC20 token pair pools is not supported.
3. For the `tick_1_inscription_ids` and `tick_2_inscription_ids` parameters:

   * If `coin_type_1` is BRC20, put the BRC20 inscription ID in the `tick_1_inscription_ids` array and leave `tick_2_inscription_ids` empty.
   * If `coin_type_2` is BRC20, put the BRC20 inscription ID in the `tick_2_inscription_ids` array and leave `tick_1_inscription_ids` empty.

   *For the same token pair, BRC20-BTC and BTC-BRC20, the same pool is created or added to (e.g., ordi-BTC, BTC-ordi), just using different fields for the parameters.*

```
```

{% endhint %}

## POST /brc20swap/v2/create\_add\_liquid\_psbt

> Build the PSBT for adding BRC20 liquidity

```json
{"openapi":"3.0.1","info":{"title":"Backend API","version":"1.0.0"},"servers":[{"url":"https://api-testnet4.dotswap.app","description":"Swap test"},{"url":"https://api.dotswap.app","description":"Swap official"}],"security":[],"paths":{"/brc20swap/v2/create_add_liquid_psbt":{"post":{"summary":"Build the PSBT for adding BRC20 liquidity","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"tick1":{"type":"string"},"tick2":{"type":"string"},"amount_1":{"type":"string"},"amount_2":{"type":"string"},"slipper":{"type":"string"},"tick_1_inscription_ids":{"type":"array","items":{"type":"string"}},"tick_2_inscription_ids":{"type":"array","items":{"type":"string"}},"payer_ord_addr":{"type":"string"},"fee_rate":{"type":"string"},"payer_btc_addr":{"type":"string"},"payer_pub_key":{"type":"string"},"check_sum":{"type":"string"},"vins":{"type":"array","items":{"type":"string"}}},"required":["tick1","tick2","amount_1","amount_2","slipper","tick_1_inscription_ids","tick_2_inscription_ids","payer_ord_addr","fee_rate","payer_btc_addr","payer_pub_key","check_sum","vins"]}}}},"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"object","properties":{"code":{"type":"integer"},"msg":{"type":"string"},"data":{"type":"object","properties":{"psbt":{"type":"string","title":"PSBT base64"},"ToSignInputs":{"type":"array","items":{"type":"object","properties":{"index":{"type":"integer"},"type":{"type":"string"}},"required":["index","type"]}},"check_sum":{"type":"string"},"tx_size":{"type":"integer"},"usr_cnt":{"type":"integer"},"vins":{"type":"array","items":{"type":"string"}}},"required":["ToSignInputs","psbt","check_sum","tx_size","usr_cnt","vins"]},"req_id":{"type":"string"}},"required":["code","msg","data","req_id"]}}},"headers":{}}}}}}}
```

## Important Notes:

{% hint style="info" %}

1. Upon successful pre-add/create request, obtain the unsigned PSBT. Some of the request parameters will be from the pre-add/create request's return result.
2. Use the same address for both `payer_ord_addr` and `payer_btc_addr`.
   {% endhint %}

## POST /brc20swap/v2/add\_liquid\_by\_psbt

> Add liquidity

```json
{"openapi":"3.0.1","info":{"title":"Backend API","version":"1.0.0"},"servers":[{"url":"https://api-testnet4.dotswap.app","description":"Swap test"},{"url":"https://api.dotswap.app","description":"Swap official"}],"security":[],"paths":{"/brc20swap/v2/add_liquid_by_psbt":{"post":{"summary":"Add liquidity","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"psbt":{"type":"string","title":"PSBT base64"},"tick1":{"type":"string"},"tick2":{"type":"string"},"amount_1":{"type":"string"},"amount_2":{"type":"string"},"slipper":{"type":"string"},"payer_ord_addr":{"type":"string"},"fee_rate":{"type":"string"},"payer_btc_addr":{"type":"string"},"payer_pub_key":{"type":"string"},"check_sum":{"type":"string"},"chl":{"type":"string"},"coin_type_1":{"type":"string"},"coin_type_2":{"type":"string"},"token":{"type":"string"}},"required":["tick1","coin_type_1","amount_1","tick2","coin_type_2","amount_2","fee_rate","slipper","token","payer_ord_addr","payer_btc_addr","payer_pub_key","psbt"]}}}},"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"object","properties":{"code":{"type":"integer"},"msg":{"type":"string"},"data":{"type":"object","properties":{"order_id":{"type":"string","title":"Order number"}},"required":["order_id"]},"req_id":{"type":"string"}},"required":["code","msg","data","req_id"]}}},"headers":{}}}}}}}
```

Finally, send the signed PSBT. If the response indicates success, the liquidity has been added/created successfully.