Every tool, and the question it answers.
12 of them. Each one answers a decision rather than naming an instrument, which is the whole selection rule and why there are 12 rather than forty.
What you have now
What actually reaches you, and what it is already spoken for.
Debt and safety
What you owe, and the buffer that stops you owing more.
What it grows into
Time, inflation and tax, applied to the same assumption.
Before your first salary
For 13 to 18: what things cost when measured in work and in years.
All of them run in your browser. Nothing you type is sent anywhere, and there is no account to make. Educational, not advice.