Built a free dealer-gamma (GEX) map for SPX/SPY/QQQ — tell me where the methodology is wrong.

GEX tools run $99–699/mo and the math underneath is standard: options chain OI, greeks, sign assumptions, sum. That's commodity data plus packaging. So I built the map I wanted and put it up free. What it shows: • Dealer gamma exposure computed from the full chain for SPX, SPY, QQQ (any ticker typeable — single names included) • Levels drawn on the price chart, not a table: call wall, put wall, gamma flip, strongest magnet strike • Second-order dealer flows: vanna, charm, and net dealer delta — with the directional read spelled out, not just a number • 1σ expected move, 0DTE share of OI (so you know if today's walls are swing-grade or expire at 4pm), air pockets in the profile • A live options-flow tape, and an intraday view of how the levels migrate — the 9:30 map is stale by noon, which matters if you trade 0DTE • A cross-index confluence check: do the SPX/SPY/QQQ maps actually agree today Where I already know it's attackable — and where I want pushback: • Dealer positioning is inferred from OI with the usual sign conventions (customers long calls/short puts against dealers, etc.). Every GEX product makes these assumptions; mine just says so out loud. If you think the convention breaks somewhere specific (0DTE flow, index vs single-name), tell me where. • The vanna/charm/dealer-delta figures inherit those same positioning assumptions, compounded — second-order estimates on first-order guesses. I show them because they're useful context, not because they're precise. Attack the error bars. • No track record page yet — "do the walls actually hold" should be measurable, and I'd rather publish the hit rate than assert it. It is not signals. It's a map of where dealer hedging is stacked. What you do at a wall is your problem. Housekeeping: OI cross-checked against CBOE. Free, no signup, no email wall, no upsell funnel. Tip jar on the site; ignore it freely. (Mods: my own free tool, posted for critique, not selling anything. Happy to remove if this breaks the rules.)