dTax is the open-source crypto tax engine a bootstrapped solo founder built after every existing tool failed his first US tax return. 22 chains, 13 cost-basis methods (FIFO, LIFO, HIFO, UK Section 104, Japan 総平均法). AI assistant grounded in your actual transaction data — no hallucinations, cites IRS rulings. Rev. Proc. 2024-28 per-wallet basis enabled by default. AGPL-3.0, self-hostable. $49/yr vs $1,999 at the leading competitor.