Kill Tilt
French. Free YouTube channel and an email-gated introductory course; the masterclasses are paid.
More resources on Poker
Poker Sciences
French, paid. A Spin & Go tracker and a pre-flop pack that gamifies range learning.
Club Poker
Free. France's largest poker community: strategy forum, hand analysis, and regular freerolls.
PioSOLVER
One-off from around 450 euros, Windows only. The free evaluation version has the full engine but solves only two example flops.
GTO Wizard
From $49/month or $39 on annual billing. The free tier gives ten trainer hands and one post-flop solution a day. Assumes solver literacy; the undisputed market leader.
WASM Postflop
Free and open source, runs in the browser. A full post-flop solver at no cost. Development is suspended, but the hosted app still works.
The Chip Race
Free. Running since 2015, hosted by two professionals with results to back the advice.