Woodland Hills financial software developer Blackline Systems Inc. added nearly 400 new clients last year. Those customers include travel services provider Priceline Group, meat processor Perdue Farms, publisher Houghton Mifflin Harcourt and bring the company’s base to more than 1,300 clients worldwide. The firm said Thursday that half of the 393 new customers are mid-market companies, a fast growing segment of its business. Seventy nine, or about 20 percent, of the new customers came from outside of North America, an increase of 4 percent from 2014. Overseas companies signing on to use Blackline’s software include Swedish shipping firm H&H Ferries, German travel services website Trivago and Malaysia Airlines. Blackline develops software that automates the processes of closing out financial books and reconciling accounts to make sure the amount of money coming in matches the money being spent. Its existing customers include Dow Chemical Co., Coca-Cola Co. and Air Medical Group Holdings.