Ryanair API
Ryanair (ryanair.com) has 2 public methods: list cheapest fares and get fare calendar. Each costs 1 credit per completed run (1¢ with pay as you go); failed runs are free.
Unofficial. Not affiliated with or endorsed by Ryanair.
Methods
2Lists the cheapest one-way Ryanair fare to each destination from a city or airport during a date range, sorted by price.
Returns destination, fare, currency, flight date and times, flight number, booking link
Readryanair.com/list_cheapest_faresGets the lowest one-way fare on each day of a month for a direct Ryanair route. For a city with several airports, it returns the airport pair with the lowest fare that month.
Returns airports, currency, cheapest day and fare, daily fares with links
Readryanair.com/get_fare_calendar