ITA matrix [1] shows prices calendar within 1 month for RT or OW, and for multicity it allows ±2 days for each leg. Although it doesn't always return the best

ITA matrix [1] shows prices calendar within 1 month for RT or OW, and for multicity it allows ±2 days for each leg. Although it doesn't always return the best results if it has to go through thousands of routes (e.g. you specify many origin & destination airports and don't restrict by airline). [1] https://matrix.itasoftware.com/ https://matrix.itasoftware.com/