Answer the everyday framing question — 2x8 or 2x10, and at what spacing? — the way the code span tables are actually built. Set a span, species/grade, and load; it sizes every standard joist against bending, shear, and deflection (the L/360 'bounce' limit), tells you which combinations work, flags the one that governs, and shows the math so you learn the method, not just the number.
Runs entirely in your browser — nothing is uploaded. Educational / preliminary sizing (NDS ASD, validated against IRC R502.3.1(2) within ~1–3 in); not a stamped design — verify with your local code, the AWC Span Calculator, and an engineer or building official before building.