15 Free Godot 4.5 Web Export GDExtension and WASM Size Pruning Resources (2026 Q2)

Primary reference for Godot 4.5 web export presets, head-include policy, threaded vs non-threaded outputs, and the runtime files that need correct MIME headers on your host.
Use for: export preset baseline.

GDExtension contract for the `.gdextension` manifest, per-platform binary entries, and the export filters that decide whether a native add-on is included in a web build at all.
Best for: web-eligible vs web-disabled audits.

Size-flag matrix covering `-Os`, `-Oz`, LTO, asyncify cost, and `MINIMAL_RUNTIME` flags that decide how lean your `.wasm` ends up before any compression layer.
Use for: raw WASM size budget.

Memory ceiling discipline for browser sandboxes - `INITIAL_MEMORY`, `MAXIMUM_MEMORY`, and `ALLOW_MEMORY_GROWTH` flags that often outweigh raw `.wasm` size as the actual cold-start bottleneck on metered devices.
Best for: runtime memory caps.

Compression contract reference for hosts - Brotli typically yields a 15-25% smaller payload than gzip on `.wasm`, but only if the host actually negotiates `br` instead of falling back to identity.
Use for: Brotli vs gzip negotiation.

Threaded web export requires `Cross-Origin-Opener-Policy: same-origin` and `Cross-Origin-Embedder-Policy: require-corp` to enable `SharedArrayBuffer` - itch.io and many static hosts default-disable both.
Best for: threaded-vs-single-thread host parity.

Free-tier hosting guidance for HTML5 uploads - file-size caps, SharedArrayBuffer toggle, embed vs full-page modes, and the `_headers` workarounds for tighter security policies.
Use for: jam-page deploy checklist.

Streaming compile and `WebAssembly.instantiateStreaming` patterns plus MIME parity (`application/wasm`) so the browser does not download the file twice or fall back to a slower path.
Best for: cold-start latency wins.

Pre-compress build outputs at quality 11 once at build time and let your host serve `.br` siblings instead of re-compressing every request - free CPU and noticeably smaller payloads vs on-the-fly gzip.
Use for: build-time Brotli artifacts.

Post-build inspection for the WebAssembly Binary Toolkit - strip debug sections, dump section sizes, and confirm Godot is not shipping unused custom name sections after a release export.
Best for: final size verification.

One-command CI gate that fails PRs when a Godot web export `.wasm` (or its `.wasm.br`) exceeds a configured byte ceiling - perfect for keeping itch.io free-tier eligibility through a long jam cycle.
Use for: automatic size regressions block.

Companion guide chapter for `.gdextension` web inventory, web-eligible vs web-disabled classification, autoload gates and export-filter strategies, plus the CI allowlist fail-closed gate this resource list points at externally.
Use for: implementation walkthrough.

Adjacent CI chapter covering threaded vs non-threaded matrix builds, `export_presets.cfg` as CI contract, and the curl MIME / COOP / COEP receipt matrix that prevents host-side regressions surfacing as silent boot hangs.
Best for: host receipt validation.

Trend-timed blog primer on the MIME / COOP / Web Audio gesture-unlock sequence so a leaner WASM still actually plays sound on first load - the size win does not help if the deploy is silent.
Use for: first-load audio smoke test.

Cross-engine help for teams maintaining both Godot and Unity web builds - the same browser-side autoplay gate and MIME parity issues bite both stacks once size pruning shifts the cold-start window.
Best for: multi-engine web debugging.