# GoCryptoTrader Backtester: Exchange package
[](https://github.com/thrasher-corp/gocryptotrader/actions/workflows/tests.yml)
[](https://github.com/thrasher-corp/gocryptotrader/blob/master/LICENSE)
[](https://godoc.org/github.com/thrasher-corp/gocryptotrader/backtester/eventhandlers/exchange)
[](https://codecov.io/gh/thrasher-corp/gocryptotrader)
[](https://goreportcard.com/report/github.com/thrasher-corp/gocryptotrader)
This exchange package is part of the GoCryptoTrader codebase.
## This is still in active development
You can track ideas, planned features and what's in progress on our [GoCryptoTrader Kanban board](https://github.com/orgs/thrasher-corp/projects/3).
Join our slack to discuss all things related to GoCryptoTrader! [GoCryptoTrader Slack](https://join.slack.com/t/gocryptotrader/shared_invite/zt-38z8abs3l-gH8AAOk8XND6DP5NfCiG_g)
## Exchange package overview
The exchange eventhandler is responsible for calling the `engine` package's `ordermanager` to place either a fake, or real order on the exchange via API.
The following steps are taken for the `ExecuteOrder` function:
- Calculate slippage. If the order is a sell order, it will reduce the price by a random percentage between the two values. If it is a buy order, it will raise the price by a random percentage between the two values
- If `RealOrders` is set to `false`:
- It will estimate the slippage based on what is in the config file under `min-slippage-percent` and `max-slippage-percent`.
- It will be sized within the constraints of the current candles OHLCV values
- It will generate the exchange fee based on what is stored in the config for the exchange asset currency pair
- If `RealOrders` is set to `true`, it will use the latest orderbook data to calculate slippage by simulating the order
- Place the order with the engine order manager
- If `RealOrders` is set to `false` it will submit the order with no calls to the exchange's API, use no API credentials and it will always pass
- If `RealOrders` is set to `true` it will submit the order via the exchange's API and if successful, will be stored in the order manager
- If an order is successfully placed, a snapshot of all existing orders in the run will be captured and store for statistical purposes
## Donations
If this framework helped you in any way, or you would like to support the developers working on it, please donate Bitcoin to:
***bc1qk0jareu4jytc0cfrhr5wgshsq8282awpavfahc***