The size of the bet
Prices are last-day-of-month closes, not a live feed. The site deliberately has no live ticker: a holder's arithmetic should not breathe with the chart.
Tools
Monthly DCA simulator, 2010–2026
Pick a dollar amount and a start month. See coins stacked, value at the last close, compound rate, and the deepest drawdown you would have watched on your way in — versus a lump sum invested the same day.
HODL capital gains tax calculator — 2026
Selling a bitcoin position? Get the bracket-accurate federal bill: 0/15/20% long-term stacking against your other income, the 3.8% NIIT trap, and how many more dollars of gains you could realize before the rate steps up.
BIP-0039 seed verifier
Paste a recovery phrase, get the checksum verdict, the entropy hex, and the master seed — computed by a SHA-512/PBKDF2 engine that runs its own published test vectors on every page load. Useful before trusting a phone camera picture of twelve words.
Supply & halving reference
The eight halvings that happened, the subsidy you are living under, the supply math to 21 million, and a sats-stacking calculator for people buying by the ten-thousand.
Why this site exists
Most bitcoin tools are built for the next trade. They refresh prices, ping exchange APIs, and ask for your account before answering a question you could answer with a pencil. This site is built for the other question: the one you check once a quarter, on purpose, with the phone face-down.
That changes what the software has to be. Historical prices are compiled once a month from a public ledger-explorer dataset and shipped to your browser as 12 kilobytes of text, not streamed from an API that can go down, move, or start logging you. The tax tables come from the IRS revenue procedure that sets the year's brackets, copied into a plain-JavaScript engine with the source document stamped on every page. The seed checker implements BIP-0039 directly and verifies itself against the vectors published with that standard, on every load, before you paste anything.
Nothing here gives advice. It gives arithmetic you can audit: the inputs are yours, the math is printed, the test vectors are named. If a number looks wrong, say so and the fix ships with a source line.