Here you may find documentation for 1inch exchange API:
The 1inch API v3, Pathfinder, is a cutting-edge discovery and routing algorithm, which offers asset exchanges at the best rates on the market. Pathfinder finds the most efficient paths for a token swap, able to split between different protocols and even different market depths in within one protocol in the shortest possible time.
Swagger documentation can be found here:
Binance Smart Chain: https://api.1inch.exchange/swagger/binance/
This API documentation is intended for public use. If you are an enterprise with significant trading volumes please fill in the form so we can assign you a custom API endpoint. The enterprise endpoint will offer significantly better performance across market rates and response times.
Full documentation you may find here https://docs.1inch.io/api/