There is no parking in the Webworks building. However the City Hall Cark Park is facing the front door right across Eglinton Street. It’s a bit pricey but no worse than any of the others from what I can see. Cheapest option is to park in the Railway Station carpark for €6 per day. It’s maybe a 10-15 min walk.
Push-pin B below is at entrance to both Webworks and the City Hall Car Park. Push-pin A is where the big railway carpark is located.