Digit - SMS bot that monitors your bank account & saves you money

Letter to Yourself - Send a physical letter to your future self

Quicken - Stay in control of your monthly cash flows, budgets, and expenditures. Quicken provides a navigable interface where you can organize your debit, credit, and savings, and build good habits accordingly.

Future Me - Send an email to your future self

Money Manager Ex - Money Manager Ex is a free, open-source, cross-platform, easy-to-use personal finance software.

Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.