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I've been computing dealer gamma levels for my own trading for a while, and the view I always wanted , net gamma broken out by strike and expiration, so you can see whether that big number at 7700 is 0DTE or spread across three months, is paywalled everywhere. So I built it and made it free: no signup, no trial, just the grid.
[squawkflow.com/gex-heatmap](http://squawkflow.com/gex-heatmap)
It's computed from the full CBOE chain (\~29,000 contracts, \~55 expirations): gamma × OI × 100 × spot² × 0.01 per contract, calls positive / puts negative, summed per strike-expiry cell. Refreshes every 5 minutes during RTH. There's also a daily levels page (call wall, put wall, zero-gamma flip, vol trigger) and I publish the raw daily history as CSV/JSON on GitHub under CC-BY if you'd rather run your own analysis.
Two honest caveats, because I think most gamma vendors bury these:
Dealer positioning is an assumption, not an observation. OI tells you a contract exists, not which side the dealer holds. Every GEX number anyone publishes, mine, SpotGamma's, UW's, inherits the "dealers long calls, short puts" convention. Treat the levels as a map of where hedging pressure would concentrate if the convention holds.
Wall "hold rates" are conditioned on distance. A wall 4% away holds \~100% of the time mostly because price never gets there. Near-money, it's roughly a coin flip. Anyone quoting a headline hold rate without the distance conditioning is selling you the denominator.
Would genuinely appreciate it being kicked around by people who trade this stuff daily, if a number looks wrong against what you're seeing elsewhere, I want to know. It's a solo project and the whole premise is that the free version doesn't lie to you.