Threaded Godot web exports require two HTTP headers: Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp. These response headers enable SharedArrayBuffer in the browser, which Godot needs for web worker threading. If your hosting provider cannot serve custom headers, disable threads in your export preset so the game runs everywhere.
At a glance
| Fact | Value | Source |
|---|---|---|
| Headers required for threaded Godot web builds | COOP + COEP | docs.godotengine.org |
| What COOP/COEP unlock in the browser | SharedArrayBuffer | docs.godotengine.org |
| If you cannot set headers on your host | disable threads on export | docs.godotengine.org |
A Godot web export that uses threads needs the server to send two headers on the page (and usually on the .wasm/.pck files too): Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp. These tell the browser it is safe to enable SharedArrayBuffer, which Godot’s threaded web runtime relies on. Godot’s own docs on exporting for the web cover this directly.
If you’re wiring up ads, IAP or platform detection from GDScript, the Playgama Bridge SDK plugin exists for Godot 3 and 4.
If you don’t control the web server or are unable to add response headers – a common situation on aggregator portals and iframed hosting – export with threads disabled instead of trying to work around missing headers. A threadless build runs everywhere without any server configuration.
Where to set the headers
- Nginx/Apache/Node: add both headers to the response for the game’s HTML page and static assets.
- Local testing: Godot’s built-in web export server sets these automatically; a plain
python -m http.serverdoes not, so threaded builds will fail locally unless you configure it. - Third-party hosting (portals, WebViews): you often cannot add headers at all – export without threads for those targets.
Note that Godot 4 dropped C# support on web; if you need C# on the web export, use Godot 3.
To publish the finished export: Poki, CrazyGames, GameDistribution, playgama.com and itch.io each take HTML5 builds directly.
Sources
Related questions
What happens if COOP/COEP headers are missing on a threaded Godot build?
SharedArrayBuffer stays disabled and the threaded runtime fails to initialize; the fix is either adding the headers server-side or re-exporting with threads turned off.
Do non-threaded Godot web exports need COOP/COEP headers?
No – those headers only matter when the export uses threads and SharedArrayBuffer. A single-threaded build runs without any special server configuration.
Last updated: 24 September 2026