# BRC20

When selecting a token pair and clicking swap, if it is a BRC20 token, a pre-swap request is required.

## POST /brc20swap/get\_swap\_psbt\_txsize

> Get the tx size of the PSBT-based exchange

```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/get_swap_psbt_txsize":{"post":{"summary":"Get the tx size of the PSBT-based exchange","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"send_coin_type":{"type":"string","title":"The type of coin to send"},"send_tick":{"type":"string","title":"The tick of the coin to send"},"send_amount":{"title":"The amount to send","type":"string"},"receive_coin_type":{"type":"string","title":"The type of coin to receive"},"receive_tick":{"type":"string","title":"The tick of the coin to receive"},"receive_amount":{"type":"string","title":"The amount to receive"},"address":{"type":"string","title":"Address"},"slipper":{"type":"string","title":"Slippage"},"fee_rate":{"type":"integer","title":"Fee rate"},"ins":{"type":"array","items":{"type":"string"},"title":"Inscription ID","description":"Only needed when exchanging with BRC20"},"method":{"type":"string","description":"Non-cross-pool swap, cross-pool pools_swap, just pass 'pools_swap'"}},"required":["send_coin_type","send_tick","send_amount","receive_coin_type","receive_tick","receive_amount","address","fee_rate","slipper","ins","method"]}}}},"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"object","properties":{"code":{"type":"integer"},"msg":{"type":"string"},"data":{"type":"object","properties":{"tx_size":{"type":"integer","title":"PSBT tx size","description":"Pass the original value to the get_swap_psbt interface"},"ins_contain_sats":{"type":"integer","description":"The sum of satoshis in the input inscriptions"},"checksum":{"type":"string","description":"Pass the original value to the get_swap_psbt interface"},"vins":{"type":"array","items":{"type":"string"},"description":"Pass the original value to the get_swap_psbt interface"},"usr_cnt":{"type":"integer","description":"Pass the original value to the get_swap_psbt interface"}},"required":["tx_size","vins","usr_cnt"],"nullable":true}},"required":["code","msg","data"]}}},"headers":{}}}}}}}
```

{% hint style="info" %}
Use the same address for both address and btc\_address.

The response from this endpoint should be passed as is to the get\_swap\_psbt endpoint.

The current slipper (slippage) limit is 12%.
{% endhint %}

## POST /brc20swap/get\_swap\_psbt

> Get the unsigned PSBT for BRC20 exchange

```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/get_swap_psbt":{"post":{"summary":"Get the unsigned PSBT for BRC20 exchange","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"send_coin_type":{"type":"string","title":"The type of coin to send"},"send_tick":{"type":"string","title":"The tick of the coin to send"},"send_amount":{"title":"The amount to send","type":"string"},"receive_coin_type":{"type":"string","title":"The type of coin to receive"},"receive_tick":{"type":"string","title":"The tick of the coin to receive"},"receive_amount":{"type":"string","title":"The amount to receive"},"address":{"type":"string","title":"Address"},"slipper":{"type":"string"},"fee_rate":{"type":"integer"},"ins":{"type":"array","items":{"type":"string"},"description":"Only needed when exchanging with BRC20","title":"Inscription ID"},"user_public_key":{"type":"string"},"tx_size":{"type":"integer","description":"Obtained from the get_swap_psbt_txsize interface"},"checksum":{"type":"integer","description":"Obtained from the get_swap_psbt_txsize interface"},"vins":{"type":"array","items":{"type":"string"},"description":"Obtained from the get_swap_psbt_txsize interface"},"usr_cnt":{"type":"integer","description":"Obtained from the get_swap_psbt_txsize interface"},"chl":{"type":"string"},"method":{"type":"string","description":"Non-cross-pool swap, cross-pool pools_swap, just pass 'pools_swap'"}},"required":["send_coin_type","send_tick","send_amount","receive_coin_type","receive_tick","receive_amount","address","fee_rate","slipper","tx_size","checksum","vins","usr_cnt","user_public_key","ins","chl","method"]}}}},"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":"PSBT tx size"},"psbt":{"type":"string"},"check_sign_only":{"type":"boolean"}},"required":["order_id","psbt","check_sign_only"]}},"required":["code","msg","data"]}}},"headers":{}}}}}}}
```

> After a successful pre-swap request, obtain the unsigned PSBT. Some request parameters will be from the pre-swap response.

## Important Notes

{% hint style="info" %}

1. After obtaining the unsigned PSBT, the user must sign it within 30 seconds.
2. The `checksum` field should use the value from the previous request, even though the field name may differ.
3. Use the same address for both `btc_address` and `address`.
4. For `user_public_key`, provide the parameter as `public_key:public_key` for a wallet with one address, or `btc_public_key:ordi_public_key` for a wallet with two addresses.
   {% endhint %}

## POST /brc20swap/send\_swap\_psbt

> Send the signed PSBT for exchange

```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/send_swap_psbt":{"post":{"summary":"Send the signed PSBT for exchange","deprecated":false,"description":"","tags":[],"parameters":[],"requestBody":{"content":{"application/json":{"schema":{"type":"object","properties":{"order_id":{"type":"string","title":"Order ID"},"psbt":{"type":"string","title":"Signed PSBT"}},"required":["order_id","psbt"]}}}},"responses":{"200":{"description":"","content":{"application/json":{"schema":{"type":"object","properties":{"code":{"type":"integer"},"msg":{"type":"string"},"data":{"type":"object","properties":{"tx_id":{"type":"string","title":"The txid of the rawtx in PSBT"},"order_id":{"type":"string","title":"The corresponding order ID"},"need_show_task":{"type":"boolean"}},"required":["tx_id"]}},"required":["code","msg","data"]}}},"headers":{}}}}}}}
```

Finally, send the signed PSBT. If the response indicates success, the swap is successful.