Cost: Free
Bill4Time Mobile is an add-on to Bill4Time.com – the professional way to track time, manage projects, organize expenses, invoice clients and accept payment for your business.

Cost: free but needs subscription. Does have basic free service.

CaseFox® is an easy to use timekeeping and billing software for law firms, attorneys, accountants, investigators, consultants and other professionals. In addition to timekeeping and billing features, CaseFox also features rule based calendaring, task management, LEDES invoicing, partner-associate fee splitting rules, trust accounting, phone message logging, accounting ledger, discovery tracking, one-click invoicing, custom fields, conflict check, client portal, secure communication with clients and more... This iOS app can be used in conjunction with CaseFox Web App using the same credentials.

Cost: $39 - $99 per month
Calendar, time keeping, organizing app

Cost: Free

Cost: $7.99
Capture your hours and expenses. Easily track your projects and life. Designed for freelancers and small teams.

Cost:
Unlimited yearly usage $14.99/year
Unlimited monthly usage $1.49/month

Cost: Free but with in-app purchases (Pro $9.99)